Customised and Noncustomised Birth Weight Centiles and Prediction of Stillbirth and Infant Mortality and Morbidity: A Cohort Study of 979,912 Term Singleton Pregnancies in Scotland

The Impact of Emotional Responses on Female Reproduction: Fibrinolysis in the Spotlight

Fibrinolytic enzymes modify various substrates required for tissue remodeling, playing a crucial role in mechanisms underlying resilience, reward processing, ovulation, embryo implantation, and placentation. Individuals with low resilience and reduced reward responsiveness, when exposed to chronic stress, are at increased risk of experiencing a range of negative emotions. Chronic anxiety and melancholia are examples of negative emotions associated with hypercortisolism, while fear and atypical depression are characterized by systemic inflammation. Both cortisol and inflammatory cytokines stimulate the production of plasminogen activator inhibitor-1 (PAI-1), a potent fibrinolysis inhibitor. Chronic anxiety, fear, and depression are among the many hypofibrinolytic conditions increasing the risk of oligo-anovulation, miscarriage, fetal growth restriction, and preeclampsia. Although significant, the impact of negative emotions on implantation is not as obvious as on ovulation or placentation. Other hypofibrinolytic conditions that may affect female reproduction through mechanisms dependent or independent of PAI-1 include metabolic disturbances (e.g., due to consumption of highly palatable foods, often used to alleviate negative affect), inflammation, hyperhomocysteinemia, hypothyroidism, hypercortisolism, antiphospholipid antibodies, and the 4G allele of the PAI-1 gene. Benzodiazepines and antidepressants should be used with caution in the first trimester as this combination may cause malformations. Also, selective serotonin reuptake inhibitors have fibrinolytic properties that increase the risk of bleeding after surgical procedures. Psychological interventions, especially group therapy, are effective in the prevention of reproductive disorders. Controlled trials are needed to test the hypothesis that female reproductive health depends on psychological well-being, a balanced diet and physical activity, suppression of inflammation and autoantibodies, and homocysteine and hormonal homeostasis.

Diagnosis, Prevention, and Management of Fetal Growth Restriction (FGR)

Fetal growth restriction (FGR), or intrauterine growth restriction (IUGR), is still the second most common cause of perinatal mortality. The factors that contribute to fetal growth restriction can be categorized into three distinct groups: placental, fetal, and maternal. The prenatal application of various diagnostic methods can, in many cases, detect the deterioration of the fetal condition in time because the nature of the above disorder is thoroughly investigated by applying a combination of biophysical and biochemical methods, which determine the state of the embryo-placenta unit and assess the possible increased risk of perinatal failure outcome and potential for many later health problems. When considering the potential for therapeutic intervention, the key question is whether it can be utilized during pregnancy. Currently, there are no known treatment interventions that effectively enhance placental function and promote fetal weight development. Nevertheless, in cases with fetuses diagnosed with fetal growth restriction, immediate termination of pregnancy may have advantages not only in terms of minimizing perinatal mortality but primarily in terms of reducing long-term morbidity during childhood and maturity.

Mycoplasma genitalium in pregnancy, including specific co-infections, is associated with lower birthweight: A prospective cohort study

BACKGROUND

Mycoplasma genitalium infection in pregnancy is increasingly reported at similar frequencies to other sexually transmitted infections (STIs). Knowledge on its contribution to adverse pregnancy outcomes is very limited, especially relative to other STIs or bacterial vaginosis (BV). Whether M. genitalium influences birthweight remains unanswered.

METHODS

Associations between birthweight and M. genitalium and other STIs (Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis) and BV in pregnancy were examined in 416 maternal-newborn pairs from a prospective cohort study in Papua New Guinea.

FINDINGS

Compared to uninfected women, M. genitalium (-166.9 g, 95% confidence interval [CI]: -324.2 to -9.7 g, p = 0.038) and N. gonorrhoeae (-274.7 g, 95% CI: -561.9 to 12.5 g, p = 0.061) infections were associated with lower birthweight in an adjusted analysis. The association for C. trachomatis was less clear, and T. vaginalis and BV were not associated with lower birthweight. STI prevalence was high for M. genitalium (13.9%), N. gonorrhoeae (5.0%), and C. trachomatis (20.0%); co-infections were frequent. Larger effect sizes on birthweight occurred with co-infections of M. genitalium, N. gonorrhoeae, and/or C. trachomatis.

CONCLUSION

M. genitalium is a potential contributor to lower birthweight, and co-infections appear to have a greater negative impact on birthweight. Trials examining the impact of early diagnosis and treatment of M. genitalium and other STIs in pregnancy and preconception are urgently needed.

FUNDING

Funding was received from philanthropic grants, the National Health and Medical Research Council, and the Burnet Institute. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Tadalafil for Treatment of Fetal Growth Restriction: A Review of Experimental and Clinical Studies

Fetal growth restriction (FGR) is a major concern in perinatal care. Various medications have been proposed as potential treatments for this serious condition. Nonetheless, there is still no definitive treatment. We studied tadalafil, a phosphodiesterase-5 inhibitor, as a therapeutic agent for FGR in clinical studies and animal experiments. In this review, we summarize our preclinical and clinical data on the use of tadalafil for FGR. Our studies in mouse models indicated that tadalafil improved FGR and hypertensive disorders of pregnancy. A phase II trial we conducted provided evidence supporting the efficacy of tadalafil in prolonging pregnancy (52.4 vs. 36.8 days; p = 0.03) and indicated a good safety profile for fetuses and neonates. Fetal, neonatal, and infant mortality was significantly lower in mothers receiving tadalafil treatment than that in controls (total number: 1 vs. 7, respectively; p = 0.03), and no severe adverse maternal events associated with tadalafil were observed. Although further studies are needed to establish the usefulness of tadalafil in FGR treatment, our research indicates that the use of tadalafil in FGR treatment may be a paradigm shift in perinatal care.

The influence of birthweight on mortality and severe neonatal morbidity in late preterm and term infants: an Australian cohort study

Background

The aim of this study was to detail incidence rates and relative risks for severe adverse perinatal outcomes by birthweight centile categories in a large Australian cohort of late preterm and term infants.

Methods

This was a retrospective cohort study of singleton infants (≥34+0 weeks gestation) between 2000 and 2018 in Queensland, Australia. Study outcomes were perinatal mortality, severe neurological morbidity, and other severe morbidity. Categorical outcomes were compared using Chi-squared tests. Continuous outcomes were compared using t-tests. Multinomial logistic regression investigated the effect of birthweight centile on study outcomes.

Findings

The final cohort comprised 991,042 infants. Perinatal mortality occurred in 1944 infants (0.19%). The incidence and risk of perinatal mortality increased as birthweight decreased, peaking for infants <1st centile (perinatal mortality rate 13.2/1000 births, adjusted Relative Risk Ratio (aRRR) of 12.96 (95% CI 10.14, 16.57) for stillbirth and aRRR 7.55 (95% CI 3.78, 15.08) for neonatal death). Severe neurological morbidity occurred in 7311 infants (0.74%), with the highest rate (19.6/1000 live births) in <1st centile cohort. There were 75,243 cases of severe morbidity (7.59% livebirths), with the peak incidence occurring in the <1st centile category (12.3% livebirths). The majority of adverse outcomes occurred in infants with birthweights between 10 and 90th centile. Almost 2 in 3 stillbirths, and approximately 3 in 4 cases of neonatal death, severe neurological morbidity or other severe morbidity occurred within this birthweight range.

Interpretation

Although the incidence and risk of perinatal mortality, severe neurological morbidity and severe morbidity increased at the extremes of birthweight centiles, the majority of these outcomes occurred in infants that were apparently "appropriately grown" (i.e., birthweight 10th-90th centile).

Funding

National Health and Medical Research Council, Mater Foundation, Royal Australian College of Obstetricians and Gynaecologists Women's Health Foundation - Norman Beischer Clinical Research Scholarship, Cerebral Palsy Alliance, University of Queensland Research Scholarship.

Improved estimation of the relationship between fetal growth and late stillbirth in the United States, 2014-15

In the United States the rate of stillbirth after 28 weeks' gestation (late stillbirth) is 2.7/1000 births. Fetuses that are small for gestational age (SGA) or large for gestational age (LGA) are at increased risk of stillbirth. SGA and LGA are often categorized as growth or birthweight ≤ 10th and ≥ 90th centile, respectively; however, these cut-offs are arbitrary. We sought to characterize the relationship between birthweight and stillbirth risk in greater detail. Data on singleton births between 28- and 44-weeks' gestation from 2014 to 2015 were extracted from the US Centers for Disease Control and Prevention live birth and fetal death files. Growth was assessed using customized birthweight centiles (Gestation Related Optimal Weight; GROW). The analyses included logistic regression using SGA/LGA categories and a generalized additive model (GAM) using birthweight centile as a continuous exposure. Although the SGA and LGA categories identified infants at risk of stillbirth, categorical models provided poor fits to the data within the high-risk bins, and in particular markedly underestimated the risk for the extreme centiles. For example, for fetuses in the lowest GROW centile, the observed rate was 39.8/1000 births compared with a predicted rate of 11.7/1000 from the category-based analysis. In contrast, the model-predicted risk from the GAM tracked closely with the observed risk, with the GAM providing an accurate characterization of stillbirth risk across the entire birthweight continuum. This study provides stillbirth risk estimates for each GROW centile, which clinicians can use in conjunction with other clinical details to guide obstetric management.

Lipid profile of circulating placental extracellular vesicles during pregnancy identifies foetal growth restriction risk

Small-for-gestational age (SGA) neonates exhibit increased perinatal morbidity and mortality, and a greater risk of developing chronic diseases in adulthood. Currently, no effective maternal blood-based screening methods for determining SGA risk are available. We used a high-resolution MS/MSALL shotgun lipidomic approach to explore the lipid profiles of small extracellular vesicles (sEV) released from the placenta into the circulation of pregnant individuals. Samples were acquired from 195 normal and 41 SGA pregnancies. Lipid profiles were determined serially across pregnancy. We identified specific lipid signatures of placental sEVs that define the trajectory of a normal pregnancy and their changes occurring in relation to maternal characteristics (parity and ethnicity) and birthweight centile. We constructed a multivariate model demonstrating that specific lipid features of circulating placental sEVs, particularly during early gestation, are highly predictive of SGA infants. Lipidomic-based biomarker development promises to improve the early detection of pregnancies at risk of developing SGA, an unmet clinical need in obstetrics.

Maternal plasma cortisol's effect on offspring birth weight: a Mendelian Randomisation study

BACKGROUND

Observational studies and randomized controlled trials have found evidence that higher maternal circulating cortisol levels in pregnancy are associated with lower offspring birth weight. However, it is possible that the observational associations are due to residual confounding.

METHODS

We performed two-sample Mendelian Randomisation (MR) using a single genetic variant (rs9989237) associated with morning plasma cortisol (GWAS; sample 1; N = 25,314). The association between this maternal genetic variant and offspring birth weight, adjusted for fetal genotype, was obtained from the published EGG Consortium and UK Biobank meta-analysis (GWAS; sample 2; N = up to 406,063) and a Wald ratio was used to estimate the causal effect. We also performed an alternative analysis using all GWAS reported cortisol variants that takes account of linkage disequilibrium. We also tested the genetic variant's effect on pregnancy cortisol and performed PheWas to search for potential pleiotropic effects.

RESULTS

The estimated effect of maternal circulating cortisol on birth weight was a 50 gram (95% CI, -109 to 10) lower birth weight per 1 SD higher log-transformed maternal circulating cortisol levels, using a single variant. The alternative analysis gave similar results (-33 grams (95% CI, -77 to 11)). The effect of the cortisol variant on pregnancy cortisol was 2-fold weaker than in the original GWAS, and evidence was found of pleiotropy.

CONCLUSIONS

Our findings provide some evidence that higher maternal morning plasma cortisol causes lower birth weight. Identification of more independent genetic instruments for morning plasma cortisol are necessary to explore the potential bias identified.

Exposure to metal mixtures and adverse pregnancy and birth outcomes: A systematic review

BACKGROUND

Prenatal exposure to metal mixtures is associated with adverse pregnancy and birth outcomes like low birth weight, preterm birth, and small for gestational age. However, prior studies have used individual metal analysis, lacking real-life exposure scenarios.

OBJECTIVES

This systematic review aims to evaluate the strength and consistency of the association between metal mixtures and pregnancy and birth outcomes, identify research gaps, and inform future studies and policies in this area.

METHODS

The review adhered to the updated Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) checklist, along with the guidelines for conducting systematic reviews and meta-analyses of observational studies of etiology (COSMOS-E). Our data collection involved searching the PubMed, MEDLINE, and SCOPUS databases. We utilized inclusion criteria to identify relevant studies. These chosen studies underwent thorough screening and data extraction procedures. Methodological quality evaluations were conducted using the NOS framework for cohort and case-control studies, and the AXIS tool for cross-sectional studies.

RESULTS

The review included 34 epidemiological studies, half of which focused on birth weight, and the others investigated neonate size, preterm birth, small for gestational age, miscarriage, and placental characteristics. The findings revealed significant associations between metal mixtures (including mercury (Hg), nickel (Ni), arsenic (As), cadmium (Cd), manganese (Mn), cobalt (Co), lead (Pb), zinc (Zn), barium (Ba), cesium (Cs), copper (Cu), selenium (Se), and chromium (Cr)) and adverse pregnancy and birth outcomes, demonstrating diverse effects and potential interactions.

CONCLUSION

In conclusion, this review consistently establishes connections between metal exposure during pregnancy and adverse consequences for birth weight, gestational age, and other vital birth-related metrics. This review further demonstrates the need to apply mixture methods with caution but also shows that they can be superior to traditional approaches. Further research is warranted to deeper understand the underlying mechanisms and to develop effective strategies for mitigating the potential risks associated with metal mixture exposure during pregnancy.

Relation of antepartum stillbirth to birthweight and gestational age: Prospective cohort study

OBJECTIVES

To investigate the incidence of antepartum stillbirth in relation to the distribution of neonatal/fetal weight for different gestational ages.

DESIGN

Prospective observational cohort study.

SETTING

Obstetric ultrasound departments in two UK maternity hospitals.

POPULATION

168 966 women with singleton pregnancies attending for routine antenatal care.

METHODS

We examined the incidence of antepartum stillbirths, within different birthweight and fetal weight percentile subgroups, conditioning for gestational age.

MAIN OUTCOME MEASURES

Incidence of antepartum stillbirth.

RESULTS

The risk of stillbirth progressively increased for lower birthweight. Considering the 25-75th percentile as the reference category, the relative risks for stillbirth at <37 weeks' gestation were 7.6 (95% confidence interval [CI] 5.7-10.2) <1st percentile, 2.6 (95% CI 1.8-3.7) 1 to 10th percentile, 1.4 (95% CI 0.9-2.1) 10 to 25th percentile, 0.8 (95% CI 0.4-1.5) 75 to 90th percentile, 0.8 (95% CI 0.4-1.7) 90 to 99th percentile, 0.9 (95% CI 0.3-2.5) >99th percentile. The respective values for births at ≥37 weeks' gestation were 5.0 (95% CI 2.9-8.9), 2.1 (95% CI 1.4-3.3), 1.4 (95% CI 0.9-2.1), 1.2 (95% CI 0.7-1.8), 1.0 (95% CI 0.6-1.8) and 4.0 (95% CI 1.8-9.3). The incidence of stillbirth in ongoing low-risk singleton pregnancies gradually increases for smaller fetuses at any gestational point. The higher incidence (5.56%) was evident for fetal weight <1st percentile between 24 and 28 weeks' gestation.

CONCLUSION

Fetal weight and the weight of the stillborn have a continuous association with the incidence of antepartum stillbirth which is affected by gestational age.

Perinatal outcome of fetuses predicted to be large-for-gestational age on universal third-trimester ultrasound in non-diabetic pregnancy

OBJECTIVE

To describe the perinatal outcome of fetuses predicted to be large-for-gestational age (LGA) on universal third-trimester ultrasound in non-diabetic pregnancies of women attempting vaginal delivery.

METHODS

This was a prospective population-based cohort study of patients from a single tertiary maternity unit in the UK offering universal third-trimester ultrasound and practicing expectant management of suspected LGA until 41-42 weeks. All women with a singleton pregnancy and an estimated due date between January 2014 and September 2019 were included. Women delivering before 37 weeks, those having a planned Cesarean delivery, those with pre-existing or gestational diabetes, those with fetal abnormalities and those who did not undergo a third-trimester scan were excluded from the assessment of perinatal outcome of cases with LGA predicted on ultrasound after implementation of the universal scan period. Association of LGA on universal third-trimester ultrasound screening and perinatal adverse outcome was assessed, with the exposures of interest being estimated fetal weight (EFW) at the 90th -95th , > 95th and > 99th percentile. The reference group was composed of fetuses with EFW at the 30th -70th percentile. Analysis was performed using multivariate logistic regression. The evaluated adverse perinatal outcomes included a composite outcome of admission to neonatal intensive care unit, Apgar score < 7 at 5 min and arterial cord pH < 7.1 (CAO1) and a composite outcome of stillbirth, neonatal death and hypoxic ischemic encephalopathy (CAO2). Secondary maternal outcomes were induction of labor, mode of delivery, postpartum hemorrhage, shoulder dystocia and obstetric anal sphincter injury.

RESULTS

Cases with EFW > 95th percentile on universal third-trimester scan were at increased risk of CAO1 (adjusted odds ratio (aOR), 2.18 (95% CI, 1.69-2.80)) and CAO2 (aOR, 2.58 (95% CI, 1.05-6.34)). Cases with EFW at the 90th -95th percentile had a less pronounced increase in the risk of CAO1 (aOR, 1.35 (95% CI, 1.02-1.78)) and were not at increased risk of CAO2. All pregnancies with a fetus predicted to be LGA were at increased risk of all of the evaluated secondary maternal outcomes except for obstetric anal sphincter injury. The risk of adverse maternal outcome was typically higher with increasing EFW. Post-hoc exploration of data suggested that shoulder dystocia had a limited contribution to composite adverse perinatal outcomes in LGA cases (population attributable fraction of 10.8% for CAO1 and 29.1% for CAO2).

CONCLUSIONS

Cases with EFW > 95th percentile are at increased risk of severe adverse perinatal outcome, such as death and hypoxic ischemic encephalopathy. These findings should aid antenatal counseling regarding the associated risk and delivery options. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

No major differences in perinatal and maternal outcomes between uninterrupted embryo culture in time-lapse system and conventional embryo culture

STUDY QUESTION

Is embryo culture in a closed time-lapse system associated with any differences in perinatal and maternal outcomes in comparison to conventional culture and spontaneous conception?

SUMMARY ANSWER

There were no significant differences between time-lapse and conventional embryo culture in preterm birth (PTB, <37 weeks), low birth weight (LBW, >2500 g) and hypertensive disorders of pregnancy for singleton deliveries, the primary outcomes of this study.

WHAT IS KNOWN ALREADY

Evidence from prospective trials evaluating the safety of time-lapse incubation for clinical use show similar embryo development rates, implantation rates, and ongoing pregnancy and live birth rates when compared to conventional incubation. Few studies have investigated if uninterrupted culture can alter risks of adverse perinatal outcomes presently associated with IVF when compared to conventional culture and spontaneous conceptions.

STUDY DESIGN, SIZE, DURATION

This study is a Swedish population-based retrospective registry study, including 7379 singleton deliveries after fresh embryo transfer between 2013 and 2018 from selected IVF clinics. Perinatal outcomes of singletons born from time-lapse-cultured embryos were compared to singletons from embryos cultured in conventional incubators and 71 300 singletons from spontaneous conceptions. Main perinatal outcomes included PTB and LBW. Main maternal outcomes included hypertensive disorders of pregnancy (pregnancy hypertension and preeclampsia).

PARTICIPANTS/MATERIALS, SETTING, METHODS

From nine IVF clinics, 2683 singletons born after fresh embryo transfer in a time-lapse system were compared to 4696 singletons born after culture in a conventional incubator and 71 300 singletons born after spontaneous conception matched for year of birth, parity, and maternal age. Patient and treatment characteristics from IVF deliveries were cross-linked with the Swedish Medical Birth Register, Register of Birth Defects, National Patient Register and Statistics Sweden. Children born after sperm and oocyte donation cycles and after Preimplantation Genetic testing cycles were excluded. Odds ratio (OR) and adjusted OR were calculated, adjusting for relevant confounders.

MAIN RESULTS AND THE ROLE OF CHANCE

In the adjusted analyses, no significant differences were found for risk of PTB (adjusted OR 1.11, 95% CI 0.87-1.41) and LBW (adjusted OR 0.86, 95% CI 0.66-1.14) or hypertensive disorders of pregnancy; preeclampsia and hypertension (adjusted OR 0.99, 95% CI 0.67-1.45 and adjusted OR 0.98, 95% CI 0.62-1.53, respectively) between time-lapse and conventional incubation systems. A significantly increased risk of PTB (adjusted OR 1.31, 95% CI 1.08-1.60) and LBW (adjusted OR 1.36, 95% CI 1.08-1.72) was found for singletons born after time-lapse incubation compared to singletons born after spontaneous conceptions. In addition, a lower risk for pregnancy hypertension (adjusted OR 0.72 95% CI 0.53-0.99) but no significant difference for preeclampsia (adjusted OR 0.87, 95% CI 0.68-1.12) was found compared to spontaneous conceptions. Subgroup analyses showed that some risks were related to the day of embryo transfer, with more adverse outcomes after blastocyst transfer in comparison to cleavage stage transfer.

LIMITATIONS, REASONS FOR CAUTION

This study is retrospective in design and different clinical strategies may have been used to select specific patient groups for time-lapse versus conventional incubation. The number of patients is limited and larger datasets are required to obtain more precise estimates and adjust for possible effect of additional embryo culture variables.

WIDER IMPLICATIONS OF THE FINDINGS

Embryo culture in time-lapse systems is not associated with major differences in perinatal and maternal outcomes, compared to conventional embryo culture, suggesting that this technology is an acceptable alternative for embryo incubation.

STUDY FUNDING/COMPETING INTEREST(S)

The study was financed by a research grant from Gedeon Richter. There are no conflicts of interest for all authors to declare.

TRIAL REGISTRATION NUMBER

N/A.

Stillbirth risk and smallness for gestational age according to Hadlock, INTERGROWTH-21st, WHO, and GROW fetal weight standards: analysis by maternal ethnicity and body mass index

BACKGROUND

Appropriate growth charts are essential for fetal surveillance, to confirm that growth is proceeding normally and to identify pregnancies that are at risk. Many stillbirths are avoidable through antenatal detection of the small-for-gestational-age fetus. In the absence of an international consensus on which growth chart to use, it is essential that clinical practice reflects outcome-based evidence.

OBJECTIVE

This study investigated the performance of 4 internationally used fetal weight standards and their ability to identify stillbirth risk in different ethnic and maternal size groups of a heterogeneous population.

STUDY DESIGN

We analyzed routinely collected maternity data from more than 2.2 million pregnancies. Three population-based fetal weight standards (Hadlock, Intergrowth-21st, and World Health Organization) were compared with the customized GROW standard that was adjusted for maternal height, weight, parity, and ethnic origin. Small-for-gestational-age birthweight and stillbirth risk were determined for the 2 largest ethnic groups in our population (British European and South Asian), in 5 body mass index categories, and in 4 maternal size groups with normal body mass index (18.5-25.0 kg/m2). The differences in trend between stillbirth and small-for-gestational-age rates were assessed using the Clogg z test, and differences between stillbirths and body mass index groups were assessed using the chi-square trend test.

RESULTS

Stillbirth rates (per 1000) were higher in South Asian pregnancies (5.51) than British-European pregnancies (3.89) (P<.01) and increased in both groups with increasing body mass index (P<.01). Small-for-gestational-age rates were 2 to 3-fold higher for South Asian babies than British European babies according to the population-average standards (Hadlock: 26.2% vs 12.2%; Intergrowth-21st: 12.1% vs 4.9%; World Health Organization: 32.2% vs 16.0%) but were similar by the customized GROW standard (14.0% vs 13.6%). Despite the wide variation, each standard's small-for-gestation-age cases had increased stillbirth risk compared with non-small-for-gestation-age cases, with the magnitude of risk inversely proportional to the rate of cases defined as small for gestational age. All standards had similar stillbirth risk when the small-for-gestation-age rate was fixed at 10% by varying their respective thresholds for defining small for gestational age. When analyzed across body mass index subgroups, the small-for-gestation-age rate according to the GROW standard increased with increasing stillbirth rate, whereas small-for-gestation-age rates according to Hadlock, Intergrowth-21st, and World Health Organization fetal weight standards declined with increasing body mass index, showing a difference in trend (P<.01) to stillbirth rates across body mass index groups. In the normal body mass index subgroup, stillbirth rates showed little variation across maternal size groups; this trend was followed by GROW-based small-for-gestation-age rates, whereas small-for-gestation-age rates defined by each population-average standard declined with increasing maternal size.

CONCLUSION

Comparisons between population-average and customized fetal growth charts require examination of how well each standard identifies pregnancies at risk of adverse outcomes within subgroups of any heterogeneous population. In both ethnic groups studied, increasing maternal body mass index was accompanied by increasing stillbirth risk, and this trend was reflected in more pregnancies being identified as small for gestational age only by the customized standard. In contrast, small-for-gestation-age rates fell according to each population-average standard, thereby hiding the increased stillbirth risk associated with high maternal body mass index.

Effects of the maternal and fetal proteome on birth weight: a Mendelian randomization analysis

Fetal growth is an indicator of fetal survival, regulated by maternal and fetal factors, but little is known about the underlying molecular mechanisms. We used Mendelian randomization to explore the effects of maternal and fetal genetically-instrumented plasma proteins on birth weight using genome-wide association summary data (n=406,063 with maternal and/or fetal genotype), with independent replication (n=74,932 mothers and n=62,108 offspring), and colocalisation. Higher genetically-predicted maternal levels of PCSK1 increased birthweight (mean-difference: 9g (95% CI: 5g, 13g) per 1 standard deviation protein level). Higher maternal levels of LGALS4 decreased birthweight (-54g (-29g, -80g)), as did VCAM1, RAD51D and GP1BA. In the offspring, higher genetically-predicted fetal levels of LGALS4 (46g (23g, 70g)) increased birthweight, alongside FCGR2B. Higher offspring levels of PCSK1 decreased birth weight (-9g (-16g, 4g), alongside LEPR. Results support maternal and fetal protein effects on birth weight, implicating roles for glucose metabolism, energy homeostasis, endothelial function and adipocyte differentiation.

Directive clinique no 442 : Retard de croissance intra-utérin : Dépistage, diagnostic et prise en charge en contexte de grossesse monofœtale

OBJECTIF

Le retard de croissance intra-utérin est une complication obstétricale fréquente qui touche jusqu'à 10 % des grossesses dans la population générale et qui est le plus souvent due à une pathologie placentaire sous-jacente. L'objectif de la présente directive clinique est de fournir des déclarations sommaires et des recommandations pour appuyer un protocole clinique de dépistage, diagnostic et prise en charge du retard de croissance intra-utérin pour les grossesses à risque ou atteintes.

POPULATION CIBLE

Toutes les patientes enceintes menant une grossesse monofœtale. BéNéFICES, RISQUES ET COûTS: La mise en application des recommandations de la présente directive devrait améliorer la compétence des cliniciens quant à la détection du retard de croissance intra-utérin et à la réalisation des interventions indiquées. DONNéES PROBANTES: La littérature publiée a été colligée par des recherches effectuées jusqu'en septembre 2022 dans les bases de données PubMed, Medline, CINAHL et Cochrane Library en utilisant un vocabulaire contrôlé au moyen de termes MeSH pertinents (fetal growth retardation and small for gestational age) et de mots-clés (fetal growth, restriction, growth retardation, IUGR, FGR, low birth weight, small for gestational age, Doppler, placenta, pathology). Seuls les résultats de revues systématiques, d'essais cliniques randomisés ou comparatifs et d'études observationnelles ont été retenus. La littérature grise a été obtenue par des recherches menées dans des sites Web d'organismes s'intéressant à l'évaluation des technologies dans le domaine de la santé et d'organismes connexes, dans des collections de directives cliniques, des registres d'essais cliniques et des sites Web de sociétés de spécialité médicale nationales et internationales. MéTHODES DE VALIDATION: Les auteurs ont évalué la qualité des données probantes et la force des recommandations en utilisant le cadre méthodologique GRADE (Grading of Recommendations Assessment, Development and Evaluation). Voir l'annexe A en ligne (tableau A1 pour les définitions et tableau A2 pour l'interprétation des recommandations fortes et conditionnelles [faibles]). PROFESSIONNELS CONCERNéS: Obstétriciens, médecins de famille, infirmières, sages-femmes, spécialistes en médecine fœto-maternelle, radiologistes et autres professionnels de la santé qui prodiguent des soins aux patientes enceintes. RéSUMé POUR TWITTER: Mise à jour de la directive sur le dépistage, le diagnostic et la prise en charge du retard de croissance intra-utérin pour les grossesses à risque ou atteintes. DÉCLARATIONS SOMMAIRES: RECOMMANDATIONS: Prédiction du retard de croissance intra-utérin Prévention du retard de croissance intra-utérin Détection du retard de croissance intra-utérin Examens en cas de retard de croissance intra-utérin soupçonné Prise en charge du retard de croissance intra-utérin précoce Prise en charge du retard de croissance intra-utérin tardif Prise en charge du post-partum et consultations préconception.

Guideline No. 442: Fetal Growth Restriction: Screening, Diagnosis, and Management in Singleton Pregnancies

OBJECTIVE

Fetal growth restriction is a common obstetrical complication that affects up to 10% of pregnancies in the general population and is most commonly due to underlying placental diseases. The purpose of this guideline is to provide summary statements and recommendations to support a clinical framework for effective screening, diagnosis, and management of pregnancies that are either at risk of or affected by fetal growth restriction.

TARGET POPULATION

All pregnant patients with a singleton pregnancy.

BENEFITS, HARMS, AND COSTS

Implementation of the recommendations in this guideline should increase clinician competency to detect fetal growth restriction and provide appropriate interventions.

EVIDENCE

Published literature in English was retrieved through searches of PubMed or MEDLINE, CINAHL, and The Cochrane Library through to September 2022 using appropriate controlled vocabulary via MeSH terms (fetal growth retardation and small for gestational age) and key words (fetal growth, restriction, growth retardation, IUGR, FGR, low birth weight, small for gestational age, Doppler, placenta, pathology). Results were restricted to systematic reviews, randomized controlled trials/controlled clinical trials, and observational studies. Grey literature was identified through searching the websites of health technology assessment and health technology-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALIDATION METHODS

The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See online Appendix A (Table A1 for definitions and Table A2 for interpretations of strong and conditional [weak] recommendations).

INTENDED AUDIENCE

Obstetricians, family physicians, nurses, midwives, maternal-fetal medicine specialists, radiologists, and other health care providers who care for pregnant patients.

TWEETABLE ABSTRACT

Updated guidelines on screening, diagnosis, and management of pregnancies at risk of or affected by FGR.

SUMMARY STATEMENTS

RECOMMENDATIONS: Prediction of FGR Prevention of FGR Detection of FGR Investigations in Pregnancies with Suspected Fetal Growth Restriction Management of Early-Onset Fetal Growth Restriction Management of Late-Onset FGR Postpartum management and preconception counselling.

Fitness of INTERGROWTH-21st birth weight standards for Chinese-ethnicity babies

OBJECTIVE

To determine the fitness of the INTERGROWTH-21st birth weight standards (INTERGROWTH21) for ethnic Chinese babies compared with a local reference (FOK2003).

DESIGN

Population-based analysis of territory-wide birth data.

SETTING

All public hospitals in Hong Kong.

PARTICIPANTS

Live births between 24 and 42 complete weeks' gestation during 2006-2017.

MAIN OUTCOME MEASURES

Babies' birth weight Z-scores were calculated using published methods. The two references were compared in three aspects: (1) the proportions of large-for-gestational-age (LGA) or small-for-gestational-age (SGA) infants, (2) the gestation-specific and sex-specific mean birth weight Z-scores and (3) the predictive power for SGA-related complications.

RESULTS

488 896 infants were included. Using INTERGROWTH21, among neonates born <33 weeks' gestation, the mean birth weight Z-scores per week were closer to zero (-0.2 to 0.05), while most of them were further from zero (0.06 to 0.34) after excluding infants with a high risk of abnormal intrauterine growth. Compared with FOK2003, INTERGROWTH21 classified smaller proportions of infants as SGA (8.3% vs 9.6%) and LGA (6.6% vs 7.9%), especially SGA among preterm infants (13.1% vs 17.0%). The area under the receiver operating characteristic curve for predicting SGA-related complications was greater with FOK2003 (0.674, 95% CI 0.670 to 0.677) than INTERGROWTH21 (0.658, 95% CI 0.655 to 0.661) (p<0.001).

CONCLUSIONS

INTERGROWTH21 performed less well than FOK2003, a local reference for ethnic Chinese babies, especially in infants born <33 weeks' gestation. Although the differences are clinically small, both these references performed poorly for extremely preterm infants, and thus a more robust chart based on a larger sample of appropriately selected infants is needed.

Association between perinatal mortality and morbidity and customised and non-customised birthweight centiles in Denmark, Finland, Norway, Wales, and England: comparative, population based, record linkage study

Objectives

To compare the risk of adverse perinatal outcomes according to infants who are born small for gestational age (SGA; <10th centile) or large for gestational age (LGA; >90th centile), as defined by birthweight centiles that are non-customised (ie, standardised by sex and gestational age only) and customised (by sex, gestational age, maternal weight, height, parity, and ethnic group).

Design

Comparative, population based, record linkage study with meta-analysis of results.

Setting

Denmark, Finland, Norway, Wales, and England (city of Bradford), 1986-2019.

Participants

2 129 782 infants born at term in birth registries.

Main outcome measures

Stillbirth, neonatal death, infant death, admission to neonatal intensive care unit, and low Apgar score (<7) at 5 minutes.

Results

Relative to those infants born average for gestational age (AGA), both SGA and LGA births were at increased risk of all five outcomes, but observed relative risks were similar irrespective of whether non-customised or customised charts were used. For example, for SGA versus AGA births, when non-customised and customised charts were used, relative risks pooled over countries were 3.60 (95% confidence interval 3.29 to 3.93) versus 3.58 (3.02 to 4.24) for stillbirth, 2.83 (2.18 to 3.67) versus 3.32 (2.05 to 5.36) for neonatal death, 2.82 (2.07 to 3.83) versus 3.17 (2.20 to 4.56) for infant death, 1.66 (1.49 to 1.86) versus 1.54 (1.30 to 1.81) for low Apgar score at 5 minutes, and (based on Bradford data only) 1.97 (1.74 to 2.22) versus 1.94 (1.70 to 2.21) for admission to the neonatal intensive care unit. The estimated sensitivity of combined SGA or LGA births to identify the three mortality outcomes ranged from 31% to 34% for non-customised charts and from 34% to 38% for customised charts, with a specificity of 82% and 80% with non-customised and customised charts, respectively.

Conclusions

These results suggest an increased risk of adverse perinatal outcomes of a similar magnitude among SGA or LGA term infants when customised and non-customised centiles are used. Use of customised charts for SGA/LGA births-over and above use of non-customised charts for SGA/LGA births-is unlikely to provide benefits in terms of identifying term births at risk of these outcomes.

Trends and associations between maternal characteristics and infant birthweight among Indigenous and non-Indigenous people in Tasmania, Australia: a population-based study

OBJECTIVE

This study aimed to investigate the trends and associations of maternal characteristics and birthweight among Indigenous and non-Indigenous infants.

STUDY DESIGN

This was a retrospective population-based study.

METHODS

Fourteen years (2005-2018) of birthweight and perinatal health data of live-born singletons and their mothers obtained from the Tasmanian Data Linkage Unit were used to assess the trends and associations between maternal characteristics and infant birthweight using regression modelling.

RESULTS

Compared with non-Indigenous mothers (n = 76,750), Indigenous mothers (n = 3805) had a significantly higher prevalence of risk factors during the 14-year period. Although the prevalence of prepregnancy obesity and gestational diabetes mellitus (GDM) markedly increased in both groups, the rate of increase was higher (P < 0.001) for Indigenous than non-Indigenous mothers. Smoking, alcohol consumption and illegal drug use during pregnancy reduced over the years, and there was no significant difference in the rate of reduction between the groups. Large-for-gestational-age (LGA) births increased while small-for-gestational-age (SGA) births decreased in both groups over time. In addition, high birthweight (HBW) births decreased while low birthweight (LBW) births increased. The rates of increase in LGA and LBW births and the rates of decrease in SGA and HBW births were significantly higher in Indigenous mothers compared with non-Indigenous mothers (P < 0.001 for all). The association between Indigenous ethnicity and LBW and SGA births weakened after adjusting for other confounding maternal and perinatal variables. LBW and SGA were positively associated with Indigenous ethnicity, age <18 years, smoking, alcohol consumption and illegal drug use, pre-eclampsia, underweight prepregnancy body mass index and low socio-economic status. Women with higher parity, pre-existing diabetes and prepregnancy overweight or obesity were more likely to give birth to an infant with HBW or LGA.

CONCLUSIONS

The prevalence of risk factors for abnormal birthweight is higher among Tasmanian Indigenous mothers, contributing to a gap in birthweight outcomes between Indigenous and non-Indigenous infants. The dramatic increase in prepregnancy obesity and GDM in both groups highlight the importance of screening and management of GDM during pregnancy. Comprehensive programmes co-designed and co-managed in consultation with Indigenous people are needed to support healthy lifestyle choices among Indigenous women to address the barriers to individuals adopting behaviour change and to help close the health outcomes-related gap between Indigenous and non-Indigenous mothers and infants.

Fetal Biometric Assessment and Infant Developmental Prognosis of the Tadalafil Treatment for Fetal Growth Restriction

Background and Objectives: Tadalafil is expected to treat fetal growth restriction (FGR), a risk factor for stillbirth and neonatal morbidity. This study aimed to evaluate the fetal biometric growth pattern of fetuses with FGR treated with tadalafil by ultrasonographic assessment. Materials and Methods: This was a retrospective study. Fifty fetuses diagnosed with FGR and treated by maternal administration of tadalafil and ten controls who received conventional treatment at Mie University Hospital from 2015 to 2019 were assessed. Fetal biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL), and estimated fetal weight (EFW) at the start of treatment and at two weeks and four weeks of treatment were mainly assessed by ultrasound examination. The Wilcoxon signed-rank test was used to assess the measures. The Kyoto Scale of Psychological Development (KSPD) was used to assess the developmental prognosis on tadalafil-treated children at 1.5 years of corrected age (CA) and 3 years old. Results: The median gestational age at the start of treatment was 30 and 31 weeks in the tadalafil and control groups, respectively, and the median gestational age at delivery was 37 weeks in both groups. The Z-score of HC was significantly increased at 4 weeks of treatment (p = 0.005), and the umbilical artery resistance index was significantly decreased (p = 0.049), while no significant difference was observed in the control group. The number of cases with an abnormal score of less than 70 on the KSPD test was 19% for P-M, 8% for C-A, 19% for L-S, and 11% for total area at 1.5 years CA. At 3 years old, the respective scores were 16%, 21%, 16%, and 16%. Conclusions: Tadalafil treatment for FGR may maintain fetal HC growth and infants' neuro-developmental prognosis.

Perinatal mortality rate and adverse perinatal outcomes presumably attributable to placental dysfunction in (near) term gestation: A nationwide 5-year cohort study

INTRODUCTION

Placental dysfunction can lead to perinatal hypoxic events including stillbirth. Unless there is overt severe fetal growth restriction, placental dysfunction is frequently not identified in (near) term pregnancy, particularly because fetal size is not necessarily small. This study aimed to evaluate, among (near) term births, the burden of hypoxia-related adverse perinatal outcomes reflected in an association with birth weight centiles as a proxy for placental function.

MATERIAL AND METHOD

A nationwide 5-year cohort of the Dutch national birth registry (PeriNed) including 684,938 singleton pregnancies between 36+0 and 41+6 weeks of gestation. Diabetes, congenital anomalies, chromosomal abnormalities and non-cephalic presentations at delivery were excluded. The main outcome was antenatal mortality rate according to birthweight centiles and gestational age. Secondary outcomes included perinatal hypoxia-related outcomes, including perinatal death and neonatal morbidity, analyzed according to birthweight centiles.

RESULTS

Between 2015 and 2019, 1,074 perinatal deaths (0.16%) occurred in the study population (n = 684,938), of which 727 (0.10%) antenatally. Of all antenatal- and perinatal deaths, 29.4% and 27.9% occurred in birthweights below the 10th centile. The incidence of perinatal hypoxia-related outcomes was highest in fetuses with lowest birthweight centiles (18.0%), falling gradually up to the 50th and 90th centile where the lowest rates of hypoxia-related outcomes (5.4%) were observed.

CONCLUSION

Perinatal hypoxia-related events have the highest incidence in the lowest birthweight centiles but are identifiable throughout the entire spectrum. In fact, the majority of the adverse outcome burden in absolute numbers occurs in the group with a birthweight above the 10th centile. We hypothesize that in most cases these events are attributable to reduced placental function. Additional diagnostic modalities that indicate placental dysfunction at (near) term gestation throughout all birth weight centiles are eagerly wanted.

Characteristics associated with antenatally unidentified small-for-gestational-age fetuses: prospective cohort study nested within DESiGN randomized controlled trial

OBJECTIVE

To identify the clinical characteristics and patterns of ultrasound use amongst pregnancies with an antenatally unidentified small-for-gestational-age (SGA) fetus, compared with those in which SGA is identified, to understand how to design interventions that improve antenatal SGA identification.

METHODS

This was a prospective cohort study of singleton, non-anomalous SGA (birth weight < 10th centile) neonates born after 24 + 0 gestational weeks at 13 UK sites, recruited for the baseline period and control arm of the DESiGN trial. Pregnancy with antenatally unidentified SGA was defined if there was no scan or if the final scan showed estimated fetal weight (EFW) at the 10th centile or above. Identified SGA was defined if EFW was below the 10th centile at the last scan. Maternal and fetal sociodemographic and clinical characteristics were studied for associations with unidentified SGA using unadjusted and adjusted logistic regression models. Ultrasound parameters (gestational age at first growth scan, number and frequency of ultrasound scans) were described, stratified by presence of indication for serial ultrasound. Associations of unidentified SGA with absolute centile and percentage weight difference between the last scan and birth were also studied on unadjusted and adjusted logistic regression, according to time between the last scan and birth.

RESULTS

Of the 15 784 SGA babies included, SGA was not identified antenatally in 78.7% of cases. Of pregnancies with unidentified SGA, 47.1% had no recorded growth scan. Amongst 9410 pregnancies with complete data on key maternal comorbidities and antenatal complications, the risk of unidentified SGA was lower for women with any indication for serial scans (adjusted odds ratio (aOR), 0.56 (95% CI, 0.49-0.64)), for Asian compared with white women (aOR, 0.80 (95% CI, 0.69-0.93)) and for those with non-cephalic presentation at birth (aOR, 0.58 (95% CI, 0.46-0.73)). The risk of unidentified SGA was highest among women with a body mass index (BMI) of 25.0-29.9 kg/m2 (aOR, 1.15 (95% CI, 1.01-1.32)) and lowest in those with underweight BMI (aOR, 0.61 (95% CI, 0.48-0.76)) compared to women with BMI of 18.5-24.9 kg/m2 . Compared to women with identified SGA, those with unidentified SGA had fetuses of higher SGA birth-weight centile (adjusted odds for unidentified SGA increased by 1.21 (95% CI, 1.18-1.23) per one-centile increase between the 0th and 10th centiles). Duration between the last scan and birth increased with advancing gestation in pregnancies with unidentified SGA. SGA babies born within a week of the last growth scan had a mean difference between EFW and birth-weight centiles of 19.5 (SD, 13.8) centiles for the unidentified-SGA group and 0.2 (SD, 3.3) centiles for the identified-SGA group (adjusted mean difference between groups, 19.0 (95% CI, 17.8-20.1) centiles).

CONCLUSIONS

Unidentified SGA was more common amongst women without an indication for serial ultrasound, and in those with cephalic presentation at birth, BMI of 25.0-29.9 kg/m2 and less severe SGA. Ultrasound EFW was overestimated in women with unidentified SGA. This demonstrates the importance of improving the accuracy of SGA screening strategies in low-risk populations and continuing performance of ultrasound scans for term pregnancies. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Causal effects of maternal circulating amino acids on offspring birthweight: a Mendelian randomisation study

BACKGROUND

Amino acids are key to protein synthesis, energy metabolism, cell signaling and gene expression; however, the contribution of specific maternal amino acids to fetal growth is unclear.

METHODS

We explored the effect of maternal circulating amino acids on fetal growth, proxied by birthweight, using two-sample Mendelian randomisation (MR) and summary data from a genome-wide association study (GWAS) of serum amino acids levels (sample 1, n = 86,507) and a maternal GWAS of offspring birthweight in UK Biobank and Early Growth Genetics Consortium, adjusting for fetal genotype effects (sample 2, n = 406,063 with maternal and/or fetal genotype effect estimates). A total of 106 independent single nucleotide polymorphisms robustly associated with 19 amino acids (p < 4.9 × 10-10) were used as genetic instrumental variables (IV). Wald ratio and inverse variance weighted methods were used in MR main analysis. A series of sensitivity analyses were performed to explore IV assumption violations.

FINDINGS

Our results provide evidence that maternal circulating glutamine (59 g offspring birthweight increase per standard deviation increase in maternal amino acid level, 95% CI: 7, 110) and serine (27 g, 95% CI: 9, 46) raise, while leucine (-59 g, 95% CI: -106, -11) and phenylalanine (-25 g, 95% CI: -47, -4) lower offspring birthweight. These findings are supported by sensitivity analyses.

INTERPRETATION

Our findings strengthen evidence for key roles of maternal circulating amino acids during pregnancy in healthy fetal growth.

FUNDING

A full list of funding bodies that contributed to this study can be found under Acknowledgments.

Marijuana use, fetal growth, and uterine artery Dopplers

OBJECTIVE

Marijuana (MJ) use is associated with adverse effects on fetal growth. We aimed to investigate the timing of suboptimal fetal growth onset in MJ-exposed pregnancies. In addition, we aimed to explore the relationship between MJ-exposure and both abnormal uterine artery (UtA) Doppler parameters and small for gestational age (SGA).

STUDY DESIGN

This was a secondary analysis of a prospective multicenter cohort that enrolled nulliparous individuals delivering non-anomalous fetuses beyond 20 weeks' gestation. Marijuana exposure was ascertained by self-report or clinical urine toxicology testing. Ultrasound estimated fetal weights (EFWs) were assessed in participants at both 16w0d-21w6d and 22w0d-29w6d. EFWs and birth weight (BW) were converted to weight percentiles (wPCT). EFW and BW wPCTs were calculated using population-based standards. Additionally, a customized standard designed to be applicable to both EFWs and BWs within the same model was also used to allow for EFW to BW percentile trajectories. The primary outcome, longitudinal wPCT, was compared between individuals with and without MJ use in a linear mixed-effects regression model adjusting for tobacco. For modeling, wPCT was smoothed across gestational age; MJ was estimated as an intercept and linear difference in the slope of gestational age. UtA Doppler notching, resistance index (RI), and pulsatility index (PI) at 16w0d-21w6d were compared using t-test and χ2. SGA at delivery was also compared.

RESULTS

Nine thousand one hundred and sixty-three individuals met inclusion criteria; 136 (1.5%) used MJ during pregnancy. Individuals who used MJ were more likely to be younger, identify as non-Hispanic Black, and have had less education. Fetuses exposed to MJ had lower wPCT beginning at 28 weeks using population-based and customized standards, when compared to those without exposure. UtA notching, PI, and RI were similar between groups. SGA was more frequent in neonates exposed to MJ using both population-based (22 vs. 9%, p<.001) and customized (25 vs. 14%, p<.001) curves.

CONCLUSIONS

MJ-exposed fetuses were estimated to be smaller than unexposed fetuses starting at 28 weeks' gestation across both growth standards without a difference in UtA Doppler parameters.

Association of birthweight centiles and early childhood development of singleton infants born from 37 weeks of gestation in Scotland: A population-based cohort study

BACKGROUND

Birthweight centiles beyond the traditional thresholds for small or large babies are associated with adverse perinatal outcomes but there is a paucity of data about the relationship between birthweight centiles and childhood development among children born from 37 weeks of gestation. This study aims to establish the association between birthweight centiles across the whole distribution and early childhood development among children born from 37 weeks of gestation.

METHODS AND FINDINGS

This is a population-based cohort study of 686,284 singleton infants born from 37 weeks of gestation. The cohort was generated by linking pregnancy and delivery data from the Scottish Morbidity Records (2003 to 2015) and the child developmental assessment at age 2 to 3.5 years. The main outcomes were child's fine motor, gross motor, communication, and social developmental concerns measured with the Ages and Stages Questionnaires-3 (ASQ-3) and Ages and Stages Questionnaire: Social & Emotional-2 (ASQ:SE-2), and for a subset of children with additional specialist tools such as the Modified Checklist for Autism in Toddlers (M-CHAT) if the ASQ3/SE indicate these are necessary. The ASQ score for each domain was categorised as "concern" and "no concern." We used multivariate cubic regression splines to model the associations between birthweight centiles and early childhood developmental concerns. We used multivariate Poisson regression models, with cluster robust errors, to estimate the relative risks (RRs) of developmental concerns below and above the established thresholds. We adjusted for maternal age, early pregnancy body mass index (BMI), parity, year of delivery, gestational age at delivery, smoking history, substance misuse in pregnancy, alcohol intake, ethnicity, residential area deprivation index, maternal clinical conditions in pregnancy (such as diabetes and pre-eclampsia), induction of labour, and child's sex. Babies born from 37 weeks of gestation with birthweight below the 25th centile, compared to those between the 25th and 74th centile, were at higher risk of developmental concerns. Those born between the 10th and 24th centile had an RR of 1.07 (95% CI: 1.03 to 1.12, p < 0.001), between the 3rd and 9th centile had an RR: 1.18 (95% CI: 1.12 to 1.25, p < 0.001), and <3rd centile had an RR of 1.37 (95% CI: 1.24 to 1.50, p < 0.001). There was no substantial increase in the risk of early childhood developmental concerns for larger birthweight categories of 75th to 89th (RR: 1.01; 95% CI: 0.97 to 1.05; p = 0.56), 90th to 96th (RR: 0.99; 95% CI: 0.94 to 1.05; p = 0.86), and ≥97th centiles (RR: 1.04; 95% CI: 0.97 to 1.12; p = 0.27), referent to birthweight between 25th and 74th centile. The percentage of developmental concerns attributable to birthweight between the 10th and 24th centile was more than that of birthweight <3rd centile (p = 0.023) because this group includes more of the population. Approximately 2.50% (95% CI: 1.26 to 3.61) of social skills concerns and 3.00% (95% CI: 1.33 to 4.67) of fine motor developmental concerns were attributable to birthweight between the 10th and 24th centile compared to 0.90% (95% CI: 0.48 to 1.26) and 2.30% (95% CI: 1.73 to 2.67) respectively for birthweight <3rd centile. We acknowledge the limitation of ASQ as a screening tool, the subjective nature of developmental assessments (particularly for speech) among young children, and inability to control for early childhood illness and upbringing factors may have an impact on our findings.

CONCLUSIONS

We observed that from 37 weeks of gestation birthweight below the 25th centile was associated with child developmental concerns, with an association apparent at higher centiles above the conventional threshold defining small for gestational age (SGA, 3rd or 10th centile). Mild to moderate SGA is an unrecognised potentially important contributor to the prevalence of developmental concerns. Closer surveillance, appropriate parental counselling, and increased support during childhood may reduce the risks associated with lower birthweight centiles.

Tadalafil treatment for fetuses with early-onset growth restriction: a protocol for a multicentre, randomised, placebo-controlled, double-blind phase II trial (TADAFER IIb)

INTRODUCTION

TheTADAlafil treatment for Fetuses with early-onset growth Restriction: multicentrer, randomizsed, phase II trial (TADAFER II) study showed the possibility of prolonging the pregnancy period in cases of early-onset fetal growth restriction; however, it was an open-label study. To establish further evidence for the efficacy of tadalafil in this setting, we planned a multicentre, randomised, placebo-controlled, double-blind trial.

METHODS AND ANALYSIS

This trial will be conducted in 180 fetuses with fetal growth restriction enrolled from medical centres in Japan; their mothers will be randomised into three groups: arm A, receiving two times per day placebo; arm B, receiving one time per day 20 mg tadalafil and one time per day placebo and arm C, receiving 20 mg two times per day tadalafil. The primary endpoint is the prolongation of gestational age at birth, defined as days from the first day of the protocol-defined treatment to birth. To minimise bias in terms of fetal baseline conditions and timing of delivery, a fetal indication for delivery as in TADAFER II will be established in this trial. The investigator will evaluate fetal baseline conditions at enrolment and decide the timing of delivery based on this indication.

ETHICS AND DISSEMINATION

This study has been approved by Mie University Hospital Clinical Research Review Board on 22 July 2019 (S2018-007). Written informed consent will be obtained from all mothers before recruitment. Our findings will be widely disseminated through peer-reviewed publications.

TRIAL REGISTRATION

jRCTs041190065.

Using Mendelian Randomisation to Prioritise Candidate Maternal Metabolic Traits Influencing Offspring Birthweight

Marked physiological changes in pregnancy are essential to support foetal growth; however, evidence on the role of specific maternal metabolic traits from human studies is limited. We integrated Mendelian randomisation (MR) and metabolomics data to probe the effect of 46 maternal metabolic traits on offspring birthweight (N = 210,267). We implemented univariable two-sample MR (UVMR) to identify candidate metabolic traits affecting offspring birthweight. We then applied two-sample multivariable MR (MVMR) to jointly estimate the potential direct causal effect for each candidate maternal metabolic trait. In the main analyses, UVMR indicated that higher maternal glucose was related to higher offspring birthweight (0.328 SD difference in mean birthweight per 1 SD difference in glucose (95% CI: 0.104, 0.414)), as were maternal glutamine (0.089 (95% CI: 0.033, 0.144)) and alanine (0.137 (95% CI: 0.036, 0.239)). In additional analyses, UVMR estimates were broadly consistent when selecting instruments from an independent data source, albeit imprecise for glutamine and alanine, and were attenuated for alanine when using other UVMR methods. MVMR results supported independent effects of these metabolites, with effect estimates consistent with those seen with the UVMR results. Among the remaining 43 metabolic traits, UVMR estimates indicated a null effect for most lipid-related traits and a high degree of uncertainty for other amino acids and ketone bodies. Our findings suggest that maternal gestational glucose and glutamine are causally related to offspring birthweight.

Parity-Adjusted Term Neonatal Growth Chart Modifies Neonatal Morbidity and Mortality Risk Stratification

Objective: To investigate the impact of parity-customized versus population-based birth weight charts on the identification of neonatal risk for adverse outcomes in small (SGA) or large for gestational age (LGA) infants compared to appropriate for gestational age (AGA) infants. Study design: Observational, retrospective, cohort study based on electronic medical birth records at a single center between 2006 and 2017. Neonates were categorized by birth weight (BW) as SGA, LGA, or AGA, with the 10th and 90th centiles as boundaries for AGA in a standard population-based model adjusted for gestational age and gender only (POP) and a customized model adjusted for gestational age, gender, and parity (CUST). Neonates defined as SGA or LGA by one standard and not overlapping the other, are SGA/LGA CUST/POP ONLY. Analyses used a reference group of BW between the 25th and 75th centile for the population. Results: Overall 132,815 singleton, live, term neonates born to mothers with uncomplicated pregnancies were included. The customized model identified 53% more neonates as SGA-CUST ONLY who had significantly higher rates of morbidity and mortality compared to the reference group (OR = 1.33 95% CI [1.16−1.53]; p < 0.0001). Neonates defined as LGA by the customized model (LGA-CUST) and AGA by the population-based model LGA-CUST ONLY had a significantly higher risk for morbidity compared to the reference (OR = 1.36 95% CI [1.09−1.71]; p = 0.007) or the LGA POP group. Neonatal mortality only occurred in the SGA and AGA groups. Conclusions: The application of a parity-customized only birth weight chart in a population of singleton, term neonates is a simple platform to better identify birth weight related neonatal risk for morbidity and mortality.

Perinatal outcomes and placental histology in small-for-gestational-age pregnancies-A comparison of population-based and universal growth charts

OBJECTIVE

To assess obstetric, perinatal, and placental histologic findings in small-for-gestational-age (SGA) neonates according to different growth charts.

METHODS

A retrospective cohort of singleton deliveries from 2008 to 2019 were divided into SGA neonates according to the local population-based chart, SGA according to universal standard growth charts (but appropriate for gestational age [AGA] according to local charts) and AGA deliveries according to both charts.

RESULTS

A total of 626 local population SGA deliveries, 132 universal SGA and 468 AGA deliveries were compared. The local population SGA group had a significantly higher rate of preterm and cesarean deliveries. An adverse neonatal outcome occurred in 27.2% of the local population SGA group, 9.8% of the universal SGA group and 6.7% of the AGA group (P < 0.001). In the local population SGA group, placental weight was lower, birth weight to placental weight ratio was highest, and the rate of maternal malperfusion lesions was highest-55.4% versus 45.4% in the universal SGA group and 39.1% in the AGA group (P < 0.001). Villitis of unknown etiology was significantly more common and histologic chorioamnionitis was significantly less common in the local population SGA group.

CONCLUSIONS

Our findings support the use of a local population-based growth chart for the diagnosis of fetal growth restriction.

Predictive performance of newborn small for gestational age by a United States intrauterine vs birthweight-derived standard for short-term neonatal morbidity and mortality

BACKGROUND

The use of birthweight standards to define small for gestational age may fail to identify neonates affected by poor fetal growth as they include births associated with suboptimal fetal growth.

OBJECTIVE

This study aimed to compare intrauterine vs birthweight-derived standards to define newborn small for gestational age to predict neonatal morbidity and mortality.

STUDY DESIGN

This was a secondary analysis of a multicenter observational study of 118,422 births. Live-born singleton, nonanomalous newborns born at 23 to 41 weeks of gestation were included. Those with missing gestational age estimation or without a first- or second-trimester ultrasound to confirm dating, birthweight, or neonatal outcome data were excluded. Birthweight percentile was computed using an intrauterine standard (Hadlock) and a birthweight-derived standard (Olsen). We compared the test characteristics of small for gestational age (birthweight of <10th percentile) by each standard to predict a composite neonatal morbidity and mortality outcome (death before discharge, neonatal intensive care unit admission >48 hours, respiratory distress syndrome, sepsis, necrotizing enterocolitis, grade 3 or 4 intraventricular hemorrhage, or seizures). Severe composite morbidity was analyzed as a secondary outcome and was defined as death, neonatal intensive care unit admission >7 days, necrotizing enterocolitis, grade 3 or 4 intraventricular hemorrhage, or seizures. The areas under the curve using receiver-operating characteristic methodology and proportions of the primary outcome by small for gestational age status were compared by gestational age category at birth (<34, 34 0/7 to 36 6/7, ≥37 weeks).

RESULTS

Of 115,502 mother-newborn dyads in the parent study, 78,203 (67.7%) were included, with most exclusions occurring because of missing or inadequate dating information, multiple gestations, or delivery outside the gestational age range. The primary composite outcome occurred in 9.5% (95% confidence interval, 9.3-9.7), and the severe composite outcome occurred in 5.3% (95% confidence interval, 5.1-5.4). Small for gestational age was diagnosed by intrauterine and birthweight-derived standards in 14.8% and 7.4%, respectively (P<.001). Neonates considered small for gestational age only by the intrauterine standard experienced the primary outcome more than twice as often as those considered non-small for gestational age by both standards (18.4% vs 7.9%; P<.001). For the prediction of the primary outcome, small for gestational age by the intrauterine standard had higher sensitivity (29% vs 15%; P<.001) but lower specificity (87% vs 93%; P<.001) than by the birthweight standard. Both standards had weak performance overall, although the intrauterine standard had a higher area under the curve (0.58 vs 0.53; P<.001). When subanalyzed by gestational age at birth, the difference in areas under the curve was only present among preterm deliveries 34 to 36 competed weeks. Neither standard demonstrated any discrimination for morbidity prediction among term births (area under the curve, 0.50 for both). When the prediction of severe morbidity was compared, the intrauterine still had better overall prediction than the birthweight standard (areas under the curve, 0.65 vs 0.57; P<.001), although this also varied by gestational age at birth.

CONCLUSION

Among nonanomalous neonates, neither intrauterine nor birthweight-derived standards for small for gestational age accurately predicted neonatal morbidity and mortality, with no discriminatory ability at term. Small for gestational age intrauterine standards performed better than birthweight standards.

A Maternal Serum Metabolite Ratio Predicts Large for Gestational Age Infants at Term: A Prospective Cohort Study

CONTEXT

Excessive birth weight is associated with maternal and neonatal complications. However, ultrasonically estimated large for gestational age (LGA; >90th percentile) predicts these complications poorly.

OBJECTIVE

To determine whether a maternal serum metabolite ratio developed for fetal growth restriction (FGR) is predictive of birth weight across the whole range, including LGA at birth.

METHODS

Metabolites were measured using ultrahigh performance liquid chromatography-tandem mass spectroscopy. The 4-metabolite ratio was previously derived from an analysis of FGR cases and a random subcohort from the Pregnancy Outcome Prediction study. Here, we evaluated its relationship at 36 weeks of gestational age (wkGA) with birth weight in the subcohort (n = 281). External validation in the Born in Bradford (BiB) study (n = 2366) used the metabolite ratio at 24 to 28 wkGA.

RESULTS

The inverse of the metabolite ratio at 36 wkGA predicted LGA at term [the area under the receiver operating characteristic curve (AUROCC) = 0.82, 95% CI 0.73 to 0.91, P = 6.7 × 10-5]. The ratio was also inversely associated with birth weight z score (linear regression, beta = -0.29 SD, P = 2.1 × 10-8). Analysis in the BiB cohort confirmed that the ratio at 24 to 28 wkGA predicted LGA (AUROCC = 0.60, 95% CI 0.54 to 0.67, P = 8.6 × 10-5) and was inversely associated with birth weight z score (beta = -0.12 SD, P = 1.3 × 10-9).

CONCLUSIONS

A metabolite ratio which is strongly predictive of FGR is equally predictive of LGA birth weight and is inversely associated with birth weight across the whole range.

Customized versus Population Growth Standards for Morbidity and Mortality Risk Stratification Using Ultrasonographic Fetal Growth Assessment at 22 to 29 Weeks' Gestation

OBJECTIVE

The aim of study is to compare the performance of ultrasonographic customized and population fetal growth standards for prediction adverse perinatal outcomes.

STUDY DESIGN

This was a secondary analysis of the Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-to-Be, in which l data were collected at visits throughout pregnancy and after delivery. Percentiles were assigned to estimated fetal weights (EFWs) measured at 22 to 29 weeks using the Hadlock population standard and a customized standard (www.gestation.net). Areas under the curve were compared for the prediction of composite and severe composite perinatal morbidity using EFW percentile.

RESULTS

Among 8,701 eligible study participants, the population standard diagnosed more fetuses with fetal growth restriction (FGR) than the customized standard (5.5 vs. 3.5%, p < 0.001). Neither standard performed better than chance to predict composite perinatal morbidity. Although the customized performed better than the population standard to predict severe perinatal morbidity (areas under the curve: 0.56 vs. 0.54, p = 0.003), both were poor. Fetuses considered FGR by the population standard but normal by the customized standard had morbidity rates similar to fetuses considered normally grown by both standards.The population standard diagnosed FGR among black women and Hispanic women at nearly double the rate it did among white women (p < 0.001 for both comparisons), even though morbidity was not different across racial/ethnic groups. The customized standard diagnosed FGR at similar rates across groups. Using the population standard, 77% of FGR cases were diagnosed among female fetuses even though morbidity among females was lower (p < 0.001). The customized model diagnosed FGR at similar rates in male and female fetuses.

CONCLUSION

At 22 to 29 weeks' gestation, EFW percentile alone poorly predicts perinatal morbidity whether using customized or population fetal growth standards. The population standard diagnoses FGR at increased rates in subgroups not at increased risk of morbidity and at lower rates in subgroups at increased risk of morbidity, whereas the customized standard does not.

Performance of six birth-weight and estimated-fetal-weight standards for predicting adverse perinatal outcome: a 10-year nationwide population-based study

OBJECTIVE

To evaluate three birth-weight (BW) standards (Australian population-based, Fenton and INTERGROWTH-21^st ) and three estimated-fetal-weight (EFW) standards (Hadlock, INTERGROWTH-21^st and WHO) for classifying small-for-gestational age (SGA) and large-for-gestational age (LGA) and predicting adverse perinatal outcomes in preterm and term babies.

METHODS

This was a nationwide population-based study conducted on a total of 2.4 million singleton births that occurred from 24 + 0 to 40 + 6 weeks' gestation between 2004 and 2013 in Australia. The performance of the growth charts was evaluated according to SGA and LGA classification, and relative risk (RR) and diagnostic accuracy based on the areas under the receiver-operating-characteristics curves (AUCs) for stillbirth, neonatal death, perinatal death, composite morbidity and a composite of perinatal death and morbidity outcomes. The analysis was stratified according to gestational age at delivery (< 37 + 0 vs ≥ 37 + 0 weeks).

RESULTS

Following exclusions, 2 392 782 singleton births were analyzed. There were significant differences in the SGA and LGA classification and risk of adverse outcomes between the six BW and EFW standards evaluated. For the term group, compared with the other standards, the INTERGROWTH-21^st BW and EFW standards classified half the number of SGA (< 10^th centile) babies (3-4% vs 7-11%) and twice the number of LGA (> 90^th centile) babies (24-25% vs 8-15%), resulting in a smaller cohort of term SGA at higher risk of adverse outcome and a larger LGA cohort at lower risk of adverse outcome. For term SGA (< 3^rd centile) babies, the RR of perinatal death using the two INTERGROWTH-21^st standards was up to 1.5-fold higher than those of the other standards (including the WHO-EFW and Hadlock-EFW), while the INTERGROWTH-21^st -EFW standard indicated a 12-26% reduced risk of perinatal death for LGA cases across centile thresholds. Conversely, for the preterm group, the WHO-EFW and Hadlock-EFW standards identified a higher SGA classification rate than did the other standards (18-19% vs 10-11%) and a 20-65% increased risk of perinatal death in term LGA babies. All BW and EFW charts had similarly poor performance in predicting adverse outcomes, including the composite outcome (AUC range, 0.49-0.62) for both preterm (AUC range, 0.58-0.62) and term (AUC range, 0.49-0.50) cases and across centiles. Furthermore, specific centile thresholds for identifying adverse outcomes varied markedly by chart between BW and EFW standards.

CONCLUSIONS

This study addresses the recurrent problem of identifying fetuses at risk of morbidity and perinatal mortality associated with growth disorders and provides new insights into the applicability of international growth standards. Our findings of marked variation in classification and the similarly poor performance of prescriptive international standards and the other commonly used standards raise questions about whether the prescriptive international standards that were constructed for universal adoption are indeed applicable to a multiethnic population such as that of Australia. Thus, caution is needed when adopting universal standards for clinical and epidemiological use. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Fetal Growth Curves: Is There a Universal Reference?

Three modern cohort studies have an advantage over historical fetal growth references because they included diverse populations. Despite similar inclusion criteria, estimated fetal weight percentiles for gestational age varied among studies, which result in different proportions of fetuses as being classified below or above a cutoff point. A universal reference would make comparison of fetal growth simpler for clinical use and for comparison across populations but may misclassify small-for-gestational-age or large-for-gestational-age fetuses. It is important to know how a growth reference performs in a local population in relation to fetal morbidity and mortality when implementing in clinical practice.

Competing-risks model for prediction of small-for-gestational-age neonate from estimated fetal weight at 19-24 weeks' gestation

OBJECTIVE

To develop further a new competing-risks model for the prediction of a small-for-gestational-age (SGA) neonate, by including second-trimester ultrasonographic estimated fetal weight (EFW).

METHODS

This was a prospective observational study in 96 678 women with singleton pregnancy undergoing routine ultrasound examination at 19-24 weeks' gestation. All pregnancies had ultrasound biometry assessment, and EFW was calculated according to the Hadlock formula. We refitted in this large dataset a previously described competing-risks model for the joint distribution of gestational age (GA) at delivery and birth-weight Z-score, according to maternal demographic characteristics and medical history, to obtain the prior distribution. The continuous likelihood of the EFW was fitted conditionally to GA at delivery and birth-weight Z-score and modified the prior distribution, according to Bayes' theorem, to obtain individualized distributions for GA at delivery and birth-weight Z-score and therefore patient-specific risks for any cut-offs for GA at delivery and birth-weight Z-score. We assessed the discriminative ability of the model for predicting SGA with, without or independently of pre-eclampsia occurrence. A calibration study was carried out. Performance of screening was evaluated for SGA defined according to the Fetal Medicine Foundation birth-weight charts.

RESULTS

The distribution of EFW, conditional to both GA at delivery and birth-weight Z-score, was best described by a regression model. For earlier gestations, the association between EFW and birth weight was steeper. The prediction of SGA by maternal factors and EFW improved for increasing degree of prematurity and greater severity of smallness but not for coexistence of pre-eclampsia. Screening by maternal factors predicted 31%, 34% and 39% of SGA neonates with birth weight < 10^th percentile delivered at ≥ 37, < 37 and < 30 weeks' gestation, respectively, at a 10% false-positive rate, and, after addition of EFW, these rates increased to 38%, 43% and 59%, respectively; the respective rates for birth weight < 3^rd percentile were 43%, 50% and 64%. The addition of EFW improved the calibration of the model.

CONCLUSION

In the competing-risks model for prediction of SGA, the performance of screening by maternal characteristics and medical history is improved by the addition of second-trimester EFW. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Separating parental and treatment contributions to perinatal health after fresh and frozen embryo transfer in assisted reproduction: A cohort study with within-sibship analysis

BACKGROUND

Compared to naturally conceived children, adverse perinatal outcomes are more common among children born after assisted reproductive technology with fresh embryo transfer (fresh-ET) or frozen embryo transfer (frozen-ET). However, most previous studies could not adequately control for family confounding factors such as subfertility. We compared birth size and duration of pregnancy among infants born after fresh-ET or frozen-ET versus natural conception, using a within-sibship design to account for confounding by maternal factors.

METHODS AND FINDINGS

This registry-based cohort study with nationwide data from Denmark (1994-2014), Norway (1988-2015), and Sweden (1988-2015) consisted of 4,510,790 live-born singletons, 4,414,703 from natural conception, 78,095 from fresh-ET, and 17,990 from frozen-ET. We identified 33,056 offspring sibling groups with the same mother, conceived by at least 2 different conception methods. Outcomes were mean birthweight, small and large for gestational age, mean gestational age, preterm (<37 weeks, versus ≥37), and very preterm birth (<32 weeks, versus ≥32). Singletons born after fresh-ET had lower mean birthweight (-51 g, 95% CI -58 to -45, p < 0.001) and increased odds of small for gestational age (odds ratio [OR] 1.20, 95% CI 1.08 to 1.34, p < 0.001), while those born after frozen-ET had higher mean birthweight (82 g, 95% CI 70 to 94, p < 0.001) and increased odds of large for gestational age (OR 1.84, 95% CI 1.56 to 2.17, p < 0.001), compared to naturally conceived siblings. Conventional population analyses gave similar results. Compared to naturally conceived siblings, mean gestational age was lower after fresh-ET (-1.0 days, 95% CI -1.2 to -0.8, p < 0.001), but not after frozen-ET (0.3 days, 95% CI 0.0 to 0.6, p = 0.028). There were increased odds of preterm birth after fresh-ET (OR 1.27, 95% CI 1.17 to 1.37, p < 0.001), and in most models after frozen-ET, versus naturally conceived siblings, with somewhat stronger associations in population analyses. For very preterm birth, population analyses showed increased odds for both fresh-ET (OR 2.03, 95% CI 1.90 to 2.12, p < 0.001) and frozen-ET (OR 1.66, 95% CI 1.42 to 1.94, p < 0.001) compared with natural conception, but results were notably attenuated within siblings (OR 1.18, 95% CI 1.0 to 1.41, p = 0.059, and OR 0.92, 95% CI 0.67 to 1.27, p = 0.6, for fresh-ET and frozen-ET, respectively). Sensitivity analyses in full siblings, in siblings born within 3-year interval, by birth order, and restricting to single embryo transfers and blastocyst transfers were consistent with the main analyses. Main limitations were high proportions of missing data on maternal body mass index and smoking.

CONCLUSIONS

We found that infants conceived by fresh-ET had lower birthweight and increased odds of small for gestational age, and those conceived by frozen-ET had higher birthweight and increased odds of large for gestational age. Conception by either fresh-ET or frozen-ET was associated with increased odds of preterm birth. That these findings were observed within siblings, as well as in conventional multivariable population analyses, reduces the likelihood that they are explained by confounding or selection bias.

TRIAL REGISTRATION

ClinicalTrials.gov ISRCTN11780826.

Third trimester ultrasound estimated fetal weight for increasing prenatal prediction of small-for-gestational age newborns in low-risk pregnant women

AIM

The early detection of small-for-gestational age (SGA) fetuses and newborns is pivotal in the prevention of perinatal mortality.

OBJECTIVES

To compare the predictive capability of performing ultrasound-based estimated fetal weight (EFW) at 32 versus 36 weeks' gestation on the detection rate of SGA fetuses and SGA newborns at delivery, and to find a better cutoff level to consider a fetus at risk of being born small.

MATERIAL AND METHODS

Nine hundred fifteen low-risk pregnant women were assessed at both 32 and 36 weeks' gestation. EFW centile was calculated in both occasions. The rate of SGA fetuses was compared. SGA fetuses were considered when both abdominal circumference (AC) and EFW were below the 10th centile from a total of 488 delivered at our Hospital. Paired comparisons between ultrasound at 32 and 36 weeks' gestation were done to predict SGA at delivery. Percentages of SGA fetuses were compared by chi-squared test. ANOVA test was used for comparing centiles among groups. Receiver operating characteristic (ROC) curve was used to find the best cutoff ultrasound centile to predict SGA at delivery. Statistical significance was previously set at 95% level (p < .05).

RESULTS

Ultrasound-based EFW at 32 weeks showed 23 cases of SGA (2.5%) while at 36 weeks this rate increased up to 4% (37/915) (p < .000001). When comparing both outcomes, 2.8% of those catalogued as adequate-for-gestational age (AGA) at 32 weeks were cases of SGA at 36 weeks. In addition, 47.8% of those diagnosed as SGA were not confirmed at 36 weeks. Only 12.3% of SGA neonates were identified at 32 weeks' gestation ultrasound, while using the 36 weeks' gestation approach this rate increased up to 30.9%. So, only a low proportion of SGA neonates were SGA fetuses at any of these two gestational ages. However, the area under the curve (AUC) at 36 weeks was as high as 0.86. Being a matter of cutoff rather than a matter of choosing the correct variable, ROC analysis showed that the best cutoff for prediction having the best sensitivity (0.80) with the best specificity (0.77) was 28th centile of EFW. This represents 24.9% of the studied women (228/915).

CONCLUSIONS

In general, ultrasound at 36 weeks has better performance detecting SGA fetuses than ultrasound at 32 weeks and we suggest to definitively change from 32 to 36 weeks in order to increase the detection rate of SGA fetuses. Moreover, in order to detect those fetuses who will grow below the lower level of the normal range in the last month of pregnancy, we suggest that those with EFW below the 28th centile at 36 weeks should be rescanned later in pregnancy to identify prenatally as many cases as we can of SGA newborns.

Wave reflections in the umbilical artery measured by Doppler ultrasound as a novel predictor of placental pathology

Background

The umbilical artery (UA) Doppler pulsatility index is used clinically to detect elevated feto-placental vascular resistance. However, this metric is confounded by variation in fetal cardiac function and is only moderately predictive of placental pathology. Our group developed a novel ultrasound methodology that measures wave reflections in the UA, thereby isolating a component of the Doppler signal that is specific to the placenta. The present study examined whether wave reflections in the UA are predictive of placental vascular pathology.

Methods

Standard clinical Doppler ultrasound of the UAs was performed in 241 pregnant women. Of these, 40 women met narrowly defined preset criteria for the control group, 36 had maternal vascular malperfusion (MVM) and 16 had fetal vascular malperfusion (FVM). Using a computational procedure, the Doppler waveforms were decomposed into a pair of forward and backward propagating waves.

Findings

Compared to controls, wave reflections were significantly elevated in women with either MVM (p<0.0001) or FVM pathology (p = 0.02). In contrast, the umbilical and uterine artery pulsatility indices were only elevated in the MVM group (p<0.0001) and there were no differences between women with FVM and the controls.

Interpretation

The measurement of wave reflections in the UA, combined with standard clinical ultrasound parameters, has the potential to improve the diagnostic performance of UA Doppler to detect placental vascular pathology. Identifying women with FVM pathology is particularly challenging prenatally and future investigations will determine if women at risk of this specific placental disease could benefit from this novel diagnostic technique.

Proposing a machine-learning based method to predict stillbirth before and during delivery and ranking the features: nationwide retrospective cross-sectional study

Background

Stillbirth is defined as fetal loss in pregnancy beyond 28 weeks by WHO. In this study, a machine-learning based method is proposed to predict stillbirth from livebirth and discriminate stillbirth before and during delivery and rank the features.

Method

A two-step stack ensemble classifier is proposed for classifying the instances into stillbirth and livebirth at the first step and then, classifying stillbirth before delivery from stillbirth during the labor at the second step. The proposed SE has two consecutive layers including the same classifiers. The base classifiers in each layer are decision tree, Gradient boosting classifier, logistics regression, random forest and support vector machines which are trained independently and aggregated based on Vote boosting method. Moreover, a new feature ranking method is proposed in this study based on mean decrease accuracy, Gini Index and model coefficients to find high-ranked features.

Results

IMAN registry dataset is used in this study considering all births at or beyond 28th gestational week from 2016/04/01 to 2017/01/01 including 1,415,623 live birth and 5502 stillbirth cases. A combination of maternal demographic features, clinical history, fetal properties, delivery descriptors, environmental features, healthcare service provider descriptors and socio-demographic features are considered. The experimental results show that our proposed SE outperforms the compared classifiers with the average accuracy of 90%, sensitivity of 91%, specificity of 88%. The discrimination of the proposed SE is assessed and the average AUC of ±95%, CI of 90.51% ±1.08 and 90% ±1.12 is obtained on training dataset for model development and test dataset for external validation, respectively. The proposed SE is calibrated using isotopic nonparametric calibration method with the score of 0.07. The process is repeated 10,000 times and AUC of SE classifiers using random different training datasets as null distribution. The obtained p-value to assess the specificity of the proposed SE is 0.0126 which shows the significance of the proposed SE.

Conclusions

Gestational age and fetal height are two most important features for discriminating livebirth from stillbirth. Moreover, hospital, province, delivery main cause, perinatal abnormality, miscarriage number and maternal age are the most important features for classifying stillbirth before and during delivery.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03658-z.

Fetal Growth Acceleration-Current Approach to the Big Baby Issue

Background and Objectives: Fetal overgrowth is related to many perinatal complications, including stillbirth, cesarean section, maternal and neonatal injuries, and shoulder dystocia. It is related to maternal diabetes, obesity, and gestational weight gain but also happens in low-risk pregnancies. There is ongoing discussion regarding definitions, methods of detection, and classification. The method used for detection is crucial as it draws a line between those at risk and low-risk popula-tions. Materials and Methods: For this narrative review, relevant evidence was identified through PubMed search with one of the general terms (macrosomia, large-for-gestational-age) combined with the outcome of interest. Results: This review summarizes evidence on the relation of fetal overgrowth with stillbirth, cesarean sections, shoulder dystocia, anal sphincter injury, and hem-orrhage. Customized growth charts help to detect mothers and fetuses at risk of those complica-tions. Relations between fetal overgrowth and diabetes, maternal weight, and gestational weight gain were investigated. Conclusions: a substantial proportion of complications are an effect of the fetus growing above its potential and should be recognized as a new dangerous condition of Fetal Growth Acceleration.

Competing-risks model for prediction of small-for-gestational-age neonate from maternal characteristics, serum pregnancy-associated plasma protein-A and placental growth factor at 11-13 weeks' gestation

OBJECTIVES

To expand a new competing-risks model for prediction of a small-for-gestational-age (SGA) neonate, by the addition of pregnancy-associated plasma protein-A (PAPP-A) and placental growth factor (PlGF), and to evaluate and compare PAPP-A and PlGF in predicting SGA.

METHODS

This was a prospective observational study of 60 875 women with singleton pregnancy undergoing routine ultrasound examination at 11 + 0 to 13 + 6 weeks' gestation. We fitted a folded-plane regression model for the PAPP-A and PlGF likelihoods. A previously developed maternal history model and the likelihood models were combined, according to Bayes' theorem, to obtain individualized distributions for gestational age (GA) at delivery and birth-weight Z-score. We assessed the discrimination and calibration of the model. McNemar's test was used to compare the detection rates for SGA with, without or independently of pre-eclampsia (PE) occurrence, of different combinations of maternal history, PAPP-A and PlGF, for a fixed false-positive rate.

RESULTS

The distributions of PAPP-A and PlGF depend on both GA at delivery and birth-weight Z-score, in the same continuous likelihood, according to a folded-plane regression model. The new approach offers the capability for risk computation for any desired birth-weight Z-score and GA at delivery cut-off. PlGF was consistently and significantly better than PAPP-A in predicting SGA delivered before 37 weeks, especially in cases with co-existence of PE. PAPP-A had similar performance to PlGF for the prediction of SGA without PE. At a fixed false-positive rate of 10%, the combination of maternal history, PlGF and PAPP-A predicted 33.8%, 43.8% and 48.4% of all cases of a SGA neonate with birth weight < 10^th percentile delivered at ≥ 37, < 37 and < 32 weeks' gestation, respectively. The respective values for birth weight < 3^rd percentile were 38.6%, 48.7% and 51.0%. The new model performed well in terms of risk calibration.

CONCLUSIONS

The combination of PAPP-A and PlGF values with maternal characteristics, according to Bayes' theorem, improves prediction of SGA. PlGF is a better predictor of SGA than PAPP-A, especially when PE is present. The new competing-risks model for SGA can be tailored to each pregnancy and to the relevant clinical requirements. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Customized birth-weight centiles and placenta-related fetal growth restriction

OBJECTIVE

The value of using customized birth-weight centiles to improve the diagnostic accuracy for fetal growth restriction (FGR), in comparison with using population-based charts, remains a matter of debate. One potential explanation for the conflicting data is that most studies used measures of perinatal mortality and morbidity as proxies for placenta-mediated FGR, many of which are not specific and may be confounded by other factors such as prematurity. The aim of this study was to compare the diagnostic accuracy of small-for-gestational age (SGA) at birth, defined according to customized vs population-based charts, for associated abnormal placental pathology.

METHODS

This was a secondary analysis of data from a prospective cohort study on risk factors for placenta-mediated complications and abnormal placental pathology in low-risk nulliparous women. All placentae were sent for detailed histopathological examination by two perinatal pathologists. The primary exposure was SGA, defined as birth weight < 10^th centile for gestational age using either a customized (SGA_cust ) or a population-based (SGA_pop ) birth-weight reference. The outcomes of interest were one of three types of abnormal placental pathology associated with FGR: maternal vascular malperfusion (MVM), chronic villitis and fetal vascular malperfusion (FVM). Adjusted relative risks (aRR) with 95% CIs were estimated using modified Poisson regression analysis, with adjustment for smoking, body mass index and aspirin treatment.

RESULTS

A total of 857 nulliparous women met the study criteria. The proportions of infants identified as SGA based on the customized and population-based charts were 12.6% (108/857) and 11.4% (98/857), respectively. A diagnosis of SGA using either customized or population-based charts was associated with an increased risk of any placental pathology (aRR, 3.04 (95% CI, 2.29-4.04) and 1.60 (95% CI, 1.10-2.31), respectively) and MVM pathology (aRR, 12.33 (95% CI, 6.60-23.03) and 5.29 (95% CI, 2.87-9.76), respectively). SGA_cust , but not SGA_pop , was also associated with an increased risk for chronic villitis (aRR, 1.85 (95% CI, 1.07-3.18)) and FVM pathology (aRR, 2.48 (95% CI, 1.25-4.93)). SGA_cust had a higher detection rate for any placental pathology (30.3% vs 17.1%; P < 0.001), MVM pathology (63.2% vs 39.5%; P = 0.003) and chronic villitis (20.8% vs 8.3%; P = 0.007) than did SGA_pop , for a similar false-positive rate. This was mainly the result of a higher detection rate for abnormal pathology in the white and East-Asian subgroups and a lower false-positive rate for abnormal pathology in the South-Asian subgroup by SGA_cust than by SGA_pop . In addition, pregnancies in the SGA_cust group, but not those in the SGA_pop group, were more likely to be complicated by preterm birth and a low 5-min Apgar score than were the corresponding non-SGA group.

CONCLUSION

These findings suggest that customized birth-weight centiles may be superior to population-based birth-weight centiles in detecting FGR that is due to underlying placental disease. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Diagnostic accuracy of fetal growth charts for placenta-related fetal growth restriction

INTRODUCTION

The choice of fetal growth chart to be used in antenatal screening for fetal growth restriction (FGR) has an important impact on the proportion of fetuses diagnosed as small for gestational age (SGA), and on the detection rate for FGR. We aimed to compare diagnostic accuracy of SGA diagnosed using four different common fetal growth charts [Hadlock, Intergrowth-21st (IG21), World Health Organization (WHO), and National Institute of Child Health and Human Development (NICHD)], for abnormal placental pathology.

METHODS

A secondary analysis of data from a prospective cohort study in low-risk nulliparous women. The exposure was SGA (birthweight <10th centile for gestational age) using each of the four charts. The outcomes were one of three types of abnormal placental pathology associated with fetal growth restriction: maternal vascular malperfusion (MVM), chronic villitis, and fetal vascular malperfusion.

RESULTS

A total of 742 nulliparous women met the study criteria. The proportion of SGA was closest to the expected rate of 10% using the Hadlock chart (12.7%). The detection rates (DR) and false positive rates (FPR) for MVM pathology were similar for the Hadlock (DR = 53.1%, FPR = 10.8%), WHO (DR = 59.4%, FPR = 14.2%), and NICHD (DR = 53.1%, FPR = 12.3%) charts, and each was superior when compared to the IG21 chart (DR = 34.4%, FPR = 3.8%, p < 0.001). The diagnosis of SGA was associated with increased risks of preeclampsia and preterm birth for all four charts.

DISCUSSION

The selection of fetal growth chart to be used in screening programs for FGR has important implications with regard to the false positive and detection rate for FGR.

Competing-risks model for prediction of small-for-gestational-age neonate from biophysical and biochemical markers at 11-13 weeks' gestation

OBJECTIVE

To develop a new competing-risks model for the prediction of a small-for-gestational-age (SGA) neonate, based on maternal factors and biophysical and biochemical markers at 11-13 weeks' gestation.

METHODS

This was a prospective observational study in 60 875 women with singleton pregnancy undergoing routine ultrasound examination at 11 + 0 to 13 + 6 weeks' gestation. All pregnancies had pregnancy-associated plasma protein-A and placental growth factor (PlGF) measurements, 59 001 had uterine artery pulsatility index (UtA-PI) measurements and 58 479 had mean arterial pressure measurements; 57 131 cases had complete data for all biomarkers. We used a previously developed competing-risks model for the joint distribution of gestational age (GA) at delivery and birth-weight Z-score, according to maternal demographic characteristics and medical history. The likelihoods of the biophysical markers were developed by fitting folded-plane regression models, a technique that has already been used in previous studies for the likelihoods of biochemical markers. The next step was to modify the prior distribution by the likelihood, according to Bayes' theorem, to obtain individualized distributions for GA at delivery and birth-weight Z-score. We used the 57 131 cases with complete data to assess the discrimination and calibration of the model for predicting SGA with, without or independently of pre-eclampsia, by different combinations of maternal factors and biomarkers.

RESULTS

The distribution of biomarkers, conditional to both GA at delivery and birth-weight Z-score, was best described by folded-plane regression models. These continuous two-dimensional likelihoods update the joint distribution of birth-weight Z-score and GA at delivery that has resulted from a competing-risks approach; this method allows application of user-defined cut-offs. The best biophysical predictor of preterm SGA was UtA-PI and the best biochemical marker was PlGF. The prediction of SGA was consistently better for increasing degree of prematurity, greater severity of smallness, coexistence of PE and increasing number of biomarkers. The combination of maternal factors with all biomarkers predicted 34.3%, 48.6% and 59.1% of all cases of a SGA neonate with birth weight < 10^th percentile delivered at ≥ 37, < 37 and < 32 weeks' gestation, at a 10% false-positive rate. The respective values for birth weight < 3^rd percentile were 39.9%, 53.2% and 64.4%, and for birth weight < 3^rd percentile with pre-eclampsia they were 46.3%, 66.8% and 80.4%. The new model was well calibrated.

CONCLUSIONS

This study has presented a single continuous two-dimensional model for prediction of SGA for any desired cut-offs of smallness and GA at delivery, laying the ground for a personalized antenatal plan for predicting and managing SGA, in the milieu of a new inverted pyramid of prenatal care. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Birthweight and gestational age-specific neonatal mortality rate in tertiary care facilities in Eastern Central Uganda

BACKGROUND

An estimated 2.8 million neonatal deaths occur each year globally, which accounts for at least 45% of deaths in children aged less than 5 years. Birthweight and gestational age-specific mortality estimates are limited in low-resource countries like Uganda. A deeper analysis of mortality by birthweight and gestational age is critical in identifying the cause and potential solutions to decrease neonatal mortality.

OBJECTIVES

We studied mortality before discharge in relation to birthweight and gestational age using a large sample size from selected tertiary care facilities in Uganda.

METHODS

We used secondary data from the East Africa Preterm Birth Initiative study conducted in six tertiary care facilities. Birth records of infants born between October 2016 and March 2019 with a gestational age greater than or equal to 24 weeks and/or birthweight greater than or equal to 500 g were reviewed for inclusion in the analysis. Newborn death before discharge was the outcome variable of interest. Multivariable Poisson regression modeling was used to explore birthweight and gestational age-specific mortality rate.

RESULTS

We analysed 50 278 birth records. Among these 95.3% (47 913) were live births and 4.8% (2365) were stillbirths. Of the 47 913 live births, 50% (24 147) were males. Overall, pre-discharge mortality was 13.0 per 1000 live births. For each 1 kg increase in birthweight, mortality before discharge decreased by -0.016. As birthweight increases, the mortality before discharge decreased from 336 per 1000 live births among infants born between 500 and 999 g, to 4.7 per 1000 live births among infants born weighing 3500 to 3999 g, and increased again to 11.2 per 1000 live births among infants weighing more than 4500 g.

CONCLUSIONS

Our study highlights the need for further research to understand newborn survival across different birthweight and gestational categories.

'Postnatal growth during the first five years of life in SGA and AGA neonates with reduced fetal growth'

BACKGROUND

Even though a lot of research has been done on postnatal growth and the occurrence of catch-up growth in small-for-gestational age (SGA) neonates, this phenomenon has not been studied well in appropriate-for-gestational age (AGA) neonates. Postnatal catch-up growth may also occur in AGA neonates indicating a compensatory mechanism for undiagnosed intrauterine growth restriction, especially in AGA neonates with reduced fetal growth velocity.

AIMS

To describe postnatal growth during the first 5 years of life in SGA and AGA neonates and evaluating the role of fetal growth velocity in catch-up growth.

STUDY DESIGN

Retrospective study in a Dutch tertiary hospital.

SUBJECTS

740 singleton neonates, without congenital anomalies, with ultrasound fetal growth data from 20 weeks and 32 weeks of pregnancy.

OUTCOME MEASURES

Postnatal growth measurements of height (cm) and weight (kg) from birth until five years of age. Postnatal catch-up growth defined as difference (delta) in both height and weight between 4 weeks and 3 years of age.

RESULTS AND CONCLUSIONS

SGA neonates had a significantly lower height and weight compared to the AGA group for all available measurement moments till 3 years. The catch-up growth between the SGA and AGA groups from 4 weeks up to 3 years after birth was not different between the two groups. However, neonates with reduced fetal growth velocity had a significantly higher risk for catch-up growth in height during the first 3 years after birth. This suggests a role for fetal growth velocity measurement in predicting fetal and subsequent postnatal growth potential.

Common maternal and fetal genetic variants show expected polygenic effects on risk of small- or large-for-gestational-age (SGA or LGA), except in the smallest 3% of babies

Babies born clinically Small- or Large-for-Gestational-Age (SGA or LGA; sex- and gestational age-adjusted birth weight (BW) <10th or >90th percentile, respectively), are at higher risks of complications. SGA and LGA include babies who have experienced environment-related growth-restriction or overgrowth, respectively, and babies who are heritably small or large. However, the relative proportions within each group are unclear. We assessed the extent to which common genetic variants underlying variation in birth weight influence the probability of being SGA or LGA. We calculated independent fetal and maternal genetic scores (GS) for BW in 11,951 babies and 5,182 mothers. These scores capture the direct fetal and indirect maternal (via intrauterine environment) genetic contributions to BW, respectively. We also calculated maternal fasting glucose (FG) and systolic blood pressure (SBP) GS. We tested associations between each GS and probability of SGA or LGA. For the BW GS, we used simulations to assess evidence of deviation from an expected polygenic model. Higher BW GS were strongly associated with lower odds of SGA and higher odds of LGA (ORfetal = 0.75 (0.71,0.80) and 1.32 (1.26,1.39); ORmaternal = 0.81 (0.75,0.88) and 1.17 (1.09,1.25), respectively per 1 decile higher GS). We found evidence that the smallest 3% of babies had a higher BW GS, on average, than expected from their observed birth weight (assuming an additive polygenic model: Pfetal = 0.014, Pmaternal = 0.062). Higher maternal SBP GS was associated with higher odds of SGA P = 0.005. We conclude that common genetic variants contribute to risk of SGA and LGA, but that additional factors become more important for risk of SGA in the smallest 3% of babies.