Prematurity and fetal growth restriction

Novel growth reference ImaGrow differed from existing charts for preterm children aged 0-2 years

AIM

This study aimed to address the critical need for more accurate growth reference charts for preterm infants, with a particular focus on low- and very low-birth-weight infants.

METHODS

The subjects were recruited at a single tertiary centre. The cohort comprised singleton and twin infants born before 37 weeks of gestation, with data collected from 2000 to 2016. Standardised measurements of body parameters were recorded in this mixed longitudinal survey. LMS method was utilised for data analysis. Statistical analysis was performed using SPSS Statistics Version 21. The validation with another new cohort was executed.

RESULTS

A total of 1781 infants (52.5% boys) met the inclusion criteria. The median gestational age at birth was 30 weeks, with a median birth weight of 1350 grams. The main findings included the construction of ImaGrow charts for low- and very low-birth-weight infants and significant differences in growth trajectories compared to Fenton+WHO charts.

CONCLUSION

Our comprehensive growth references, ImaGrow, are based on a long-term auxological assessment of preterm infants and differ from charts derived from size-at-birth standards or charts for term babies. These charts have significant implications for clinical practice in monitoring and assessing the growth of preterm infants.

Morphometric Analysis of Placenta and Fetal Doppler Indices in Normal and High-Risk Pregnancies

Background High-risk pregnancies, encompassing pregnancy-induced hypertension (PIH), gestational diabetes mellitus (GDM), preeclampsia toxemia (PET), and intrauterine growth restriction (IUGR), represent intricate medical challenges with potential repercussions for maternal and fetal health. This research undertakes a comprehensive comparative investigation into the variations of Doppler indices and placental parameters within the context of these high-risk conditions when juxtaposed against pregnancies characterized as normal. Methodology Employing a rigorous cross-sectional study design, a diverse cohort of pregnant individuals with gestational diabetes, IUGR, PIH, and preeclampsia was meticulously assembled. Additionally, a group of normal pregnant women served as the comparative reference. Doppler ultrasound assessments, viz, pulsatility index (PI), were carefully performed to estimate blood flow velocities within critical maternal and fetal vessels, while placental parameters were meticulously quantified, encompassing dimensions, vascular architecture, and morphological features. Results Except in the GDM group, all high-risk groups had reduced estimated placental weight and actual birth weight than normal pregnant women. All high-risk groups showed a highly significant elevation of the PI of the umbilical artery and PI of the middle cerebral artery (MCA) than normal but the PI of MCA was significantly reduced in the PET group than in normal individuals. The cerebro-placental ratio in the GDM and IUGR groups revealed markedly greater values, whereas PET showed lower values. IUGR and PIH groups showed a substantial reduction in the fetal birth weight. All high-risk groups (GDM, IUGR, PIH, and PET) showed a highly significant reduction in luminal area umbilical artery 1 than the normal pregnant women. In IUGR, marginal placental insertion was very high, followed by GDM and PET groups. Conclusions This study reveals that Doppler indices, placental parameters, newborn weight, and their related ratios may be utilized to anticipate gestation difficulties and gain insight into the pathophysiology of problematic conceptions.

The Effectiveness of Adequate Antenatal Care in Reducing Adverse Perinatal Outcomes: Evidence From a Low- or Middle-Income Country

Background and aim Antenatal care (ANC) is universally acknowledged as an essential intervention for enhancing the well-being of both mothers and children. The World Health Organization advises a minimum of four ANC visits. The objective of this study is to assess the effectiveness of adequate ANC in mitigating adverse perinatal outcomes. Methods This cross-sectional study was done at the Department of Obstetrics and Gynecology, Delta Medical College & Hospital, Bangladesh, from March 2023 to August 2023. A total of 226 mothers who gave birth at the hospital during this period were enrolled in the study. Results More than 87% of the participants received adequate (≥4 visits) antenatal care from a registered physician. More than 84% of the mothers gave birth via cesarean section. Among the mothers who received inadequate ANC, the proportion of adverse perinatal outcomes was higher (69.0%) than that of those who received adequate ANC (32.0%). A significant association (p<0.05) was noted between inadequate antenatal care and adverse perinatal outcomes. Pregnant women receiving adequate antenatal checkups were 79% less likely to experience adverse perinatal outcomes compared to those receiving inadequate ANC. Conclusion Adequate ANC is a very efficient and economical strategy for mitigating adverse perinatal outcomes.

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.

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.

A modular systematic review of antenatal interventions to address undernutrition during pregnancy in the prevention of low birth weight

BACKGROUND

Poor nutrition during pregnancy can lead to adverse birth outcomes including low birth weight (LBW).

OBJECTIVE

This modular systematic review aimed to provide evidence for the effects of seven antenatal nutritional interventions on the risks of LBW, preterm birth (PTB), small-for-gestational-age (SGA) and stillbirth (SB).

METHODS

We searched MEDLINE, Embase, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials and CINAHL Complete between April and June 2020, with a further update in September 2022 (Embase only). We included randomized controlled trials (RCTs) and reviews of RCTs to estimate the effect sizes of the selected interventions on the four birth outcomes.

RESULTS

Evidence suggests that balanced protein and energy (BPE) supplementation for pregnant women with undernutrition can reduce the risk of LBW, SGA and SB. Evidence from low and lower middle-income countries (MIC) suggests that multiple micronutrient (MMN) supplementation can reduce the risk of LBW and SGA in comparison with iron or iron and folic acid supplementation and lipid-based nutrient supplements (LNS) with any quantity of energy can reduce the risk of LBW in comparison with MMN supplementation. Evidence from high and upper MIC suggests that supplementation with omega-3 fatty acids (O3FA) can reduce the risk and supplementation with high-dose calcium might possibly reduce the risk of LBW and PTB. Antenatal dietary education programs might possibly reduce the risk of LBW in comparison with standard-of-care. No RCTs were identified for monitoring weight gain followed by interventions to support weight gain in women who are underweight.

CONCLUSIONS

Provision of BPE, MMN and LNS to pregnant women in populations with undernutrition can reduce the risk of LBW and related outcomes. The benefits of O3FA and calcium supplementation to this population require further investigation. Targeting interventions to pregnant women who are not gaining weight has not been tested with RCTs.

Characteristics of salivary telomere length shortening in preterm infants

OBJECTIVE

To examine the association between gestational age, telomere length (TL) and rate of shortening in newborns.

STUDY DESIGN

Genomic DNA was isolated from buccal samples of 39 term infants at birth and one year and 32 preterm infants at birth, term-adjusted age (40 weeks post-conception) and age one-year corrected for gestational duration. Telomere length was measured by quantitative real-time PCR. Demographic and clinical data were collected during clinic or research visits and from hospital records. Socioeconomic status was estimated using the deprivation category (DEPCAT) scores derived from the Carstairs score of the subject's postal code.

RESULTS

At birth, preterm infants had longer telomeres than infants born at term. However, there was no difference in telomere length between preterm infants and term infants at one year of age, implying that the rate of telomere shortening was greater in pre-term than term infants. Interestingly, TL at age 40 weeks post-conception in preterm infants was significantly longer than term infant TL at birth, suggesting that time since conception is not the only factor that affects rate of shortening. Several factors, including sex, fetal growth restriction, maternal age, maternal booking body mass index (BMI), mother education level and DEPCAT score, also differed between the preterm and term groups.

CONCLUSIONS

Preterm infants have longer telomeres than term infants at birth. In the studied cohort, the rate of telomere shortening was greater in the premature group compared with the term infants. This finding agrees with previous studies using cord blood, suggesting that the longer TL in premature infants detected at birth do not persist and demonstrating that use of saliva DNA is acceptable for studies of telomere dynamics in infants. However, that the TL at age 40 weeks post-conception in preterm is longer than term infants at birth suggests that biological factors other than time since conception also affect rate of shortening.

Evaluating the Growth Assessment Protocol for stillbirth prevention: progress and challenges

Many stillbirths are associated with fetal growth restriction, and are hence potentially avoidable. The Growth Assessment Protocol (GAP) is a multidisciplinary program with an evidence based care pathway, training in risk assessment, fetal growth surveillance with customised charts and rolling audit. Antenatal detection of small for gestational age (SGA) has become an indicator of quality of care. Evaluation is essential to understand the impact of such a prevention program. Randomised trials will not be effective if they cannot ensure proper implementation before assessment. Observational studies have allowed realistic evaluation in practice, with other factors excluded that may have influenced the outcome. An award winning 10 year study of stillbirth data in England has been able to assess the effect of GAP in isolation, and found a strong, causal association with improved antenatal detection of SGA babies, and the sustained decline in national stillbirth rates. The challenge now is to apply this program more widely in low and middle income settings where the main global burden of stillbirth is, and to adapt it to local needs and resources.

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.

Association of Placental Parameters with Low Birth Weight Among Neonates Born in the Public Hospitals of Hadiya Zone, Southern Ethiopia: An Institution-Based Cross-Sectional Study

Introduction

Placenta indices are the significant determinants of perinatal outcome and neonatal mortality. A clinician can predict neonatal status based on the findings from the placental indices. However, there are limited studies on the relationship between placental parameters and neonatal birth weight in Ethiopia. Hence, this study aimed to assess placental parameters and their association with birth weight among neonates born at public hospitals in southern Ethiopia.

Methods

A facility-based cross-sectional study was conducted on 249 systematically selected placentae with the attached umbilical cord from normal singleton live birth with known gestational age. A weighing scale, long needle, and standard non-elastic tape were used to measure placental parameters. Maternal and neonatal characteristics were obtained from the medical charts. Bivariable and multivariable logistic regressions analyses were done to assess the association between placental indices with neonatal birth weight. Finally, an adjusted odds ratio with the corresponding 95% CI was used to declare the statistical significance.

Results

In this study, the mean placental weight, diameter, and thickness were 475.9gm, 17.73cm, and 4.43cm, respectively, and the prevalence of low birth weight was 10% (95% CI: 6–14%). Low placental weight (AOR: 6.57; 95% CI: 2.47–17.48), low placental thickness (AOR: 4.94; 95% CI: 1.42–17.22), and gestational age (AOR: 4.73; 95% CI: 1.49–14.99) were associated with low birth weight.

Conclusion

This study revealed that placental parameters, particularly weight and thickness, and gestational age have a significant influence on low birth weight. Therefore, proper examination of the placenta should be performed routinely following delivery for better newborn care.

Understanding the Preterm Human Heart: What do We Know So Far?

Globally, preterm birth affects more than one in every 10 live births. Although the short‐term cardiopulmonary complications of prematurity are well known, long‐term health effects are only now becoming apparent. Indeed, preterm birth has been associated with elevated cardiovascular morbidity and mortality in adulthood. Experimental animal models and observational human studies point toward changes in heart morphology and function from birth to adulthood in people born preterm that may contribute to known long‐term risks. Moreover, recent data support the notion of a heterogeneous cardiac phenotype of prematurity, which is likely driven by various maternal, early, and late life factors. This review aims to describe the early fetal‐to‐neonatal transition in preterm birth, the different structural and functional changes of the preterm human heart across developmental stages, as well as potential factors contributing to the cardiac phenotype of prematurity.

Adverse pregnancy outcomes and occlusal traits in the primary dentition: A prospective cohort (BRISA)

OBJECTIVES

This study aimed to analyse the relationship between adverse pregnancy outcomes (APO) and occlusal traits in the primary dentition, checking for different mediation paths.

SETTING AND SAMPLE POPULATION

Children evaluated at birth (T1), between 12 and 24 months (T2), and between 24 and 36 months (T3) were included. Two hundred and seventeen children who participated in T1 and T2 were randomly selected to perform the occlusion examination.

MATERIALS AND METHODS

This is a prospective cohort study (BRISA). The theoretical model was tested by structural equation modelling (SEM), estimating standardized coefficients (Coeff.) (α = 0.05). The primary exposure was APO-a latent variable manifested from three health problems at birth: low birthweight (LBW), pre-term birth (PTB) and intrauterine growth restriction (IUGR), evaluated in T1. The outcomes were four different occlusal traits assessed in T3: overjet, anterior and posterior crossbite, and crowding. Each outcome's direct and indirect effects were tested, mediated by growth, breathing, breastfeeding, and pacifier use.

RESULTS

There was no direct association between APO and any of the outcomes: overjet (Coeff. = -0.163, P = .241), anterior crossbite (Coeff. = -0.696, P = .065), posterior crossbite (Coeff. = -0.087, P = .589) and crowding (Coeff. = 0.400, P = .423). The indirect (total and specifics) effects tested also showed no association (P > .05). However, APO was associated with lower child growth in all models; breastfeeding was associated with higher child growth in all models, and pacifier use was associated with overjet (Coeff. = 0.184, P < .001) and posterior crossbite (Coeff. = 0.373, P = .011).

CONCLUSION

APO was not a risk factor for overjet, crossbite and crowding in an early stage of the primary dentition by direct and indirect pathways. However, growth has been lower in children with APO and higher in children breastfed. Also, the harmful effects of using a pacifier in dental occlusion are highlighted.

Customized GROW vs INTERGROWTH-21st birthweight standards to identify small for gestational age associated perinatal outcomes at term

BACKGROUND

Fetal growth restriction is associated with stillbirth and other adverse pregnancy outcomes, and use of the correct weight standard is an essential proxy indicator of growth status and perinatal risk.

OBJECTIVE

We sought to assess the performance of two international birthweight standards for their ability to identify perinatal morbidity and mortality indicators associated with small for gestational age (SGA) infants at term.

STUDY DESIGN

This retrospective cohort study used data from a multi-center perinatal quality initiative including a multi-ethnic dataset of 125,826 births from 2012-2017. Of the singleton term births, 92,622 had complete outcome data including stillbirth, neonatal death, 5-minute Apgar <7, neonatal glucose instability and need for newborn transfer to a higher level of care or NICU admission. The customized (GROW) and INTERGROWTH-21^st (IG21) birthweight standards were applied to determine SGA (<10^th centile) according to their respective methods and formulae. Associations with adverse outcomes were expressed as relative risk (RR) with 95% confidence interval (CI) and population attributable fraction (PAF).

RESULTS

GROW classified 9,578 (10.3%) and IG21 classified 4,079 (4.4%) pregnancies as SGA, respectively. For all of the outcomes assessed, GROW identified more SGA infants with adverse outcomes than IG21, including more stillbirths, perinatal deaths, low Apgar scores, glucose instability, newborn seizure and transfers to a higher level of care. Thirteen of the 27 stillbirths (48%) that were SGA by either method were identified as SGA by GROW but not by IG21. Similarly, additional cases of all other adverse outcome indicators were identified by GROW as SGA, while only in one category (glucose instability) did IG21 identify 9 of 295 cases (3.1%) which were not identified as SGA by GROW.

CONCLUSION

Customized assessment using GROW results in increased identification of small for gestational age term babies that are at significantly increased risk of an array of adverse pregnancy outcomes.

Analysis of maturation features in fetal brain ultrasound via artificial intelligence for the estimation of gestational age

BACKGROUND

Optimal prenatal care relies on accurate gestational age dating. After the first trimester, the accuracy of current gestational age estimation methods diminishes with increasing gestational age. Considering that, in many countries, access to first trimester crown rump length is still difficult owing to late booking, infrequent access to prenatal care, and unavailability of early ultrasound examination, the development of accurate methods for gestational age estimation in the second and third trimester of pregnancy remains an unsolved challenge in fetal medicine.

OBJECTIVE

This study aimed to evaluate the performance of an artificial intelligence method based on automated analysis of fetal brain morphology on standard cranial ultrasound sections to estimate the gestational age in second and third trimester fetuses compared with the current formulas using standard fetal biometry.

STUDY DESIGN

Standard transthalamic axial plane images from a total of 1394 patients undergoing routine fetal ultrasound were used to develop an artificial intelligence method to automatically estimate gestational age from the analysis of fetal brain information. We compared its performance-as stand alone or in combination with fetal biometric parameters-against 4 currently used fetal biometry formulas on a series of 3065 scans from 1992 patients undergoing second (n=1761) or third trimester (n=1298) routine ultrasound, with known gestational age estimated from crown rump length in the first trimester.

RESULTS

Overall, 95% confidence interval of the error in gestational age estimation was 14.2 days for the artificial intelligence method alone and 11.0 when used in combination with fetal biometric parameters, compared with 12.9 days of the best method using standard biometrics alone. In the third trimester, the lower 95% confidence interval errors were 14.3 days for artificial intelligence in combination with biometric parameters and 17 days for fetal biometrics, whereas in the second trimester, the 95% confidence interval error was 6.7 and 7, respectively. The performance differences were even larger in the small-for-gestational-age fetuses group (14.8 and 18.5, respectively).

CONCLUSION

An automated artificial intelligence method using standard sonographic fetal planes yielded similar or lower error in gestational age estimation compared with fetal biometric parameters, especially in the third trimester. These results support further research to improve the performance of these methods in larger studies.

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.

A hierarchical procedure to select intrauterine and extrauterine factors for methodological validation of preterm birth risk estimation

Background

Etiopathogenesis of preterm birth (PTB) is multifactorial, with a universe of risk factors interplaying between the mother and the environment. It is of utmost importance to identify the most informative factors in order to estimate the degree of PTB risk and trace an individualized profile. The aims of the present study were: 1) to identify all acknowledged risk factors for PTB and to select the most informative ones for defining an accurate model of risk prediction; 2) to verify predictive accuracy of the model and 3) to identify group profiles according to the degree of PTB risk based on the most informative factors.

Methods

The Maternal Frailty Inventory (MaFra) was created based on a systematic review of the literature including 174 identified intrauterine (IU) and extrauterine (EU) factors. A sample of 111 pregnant women previously categorized in low or high risk for PTB below 37 weeks, according to ACOG guidelines, underwent the MaFra Inventory. First, univariate logistic regression enabled p-value ordering and the Akaike Information Criterion (AIC) selected the model including the most informative MaFra factors. Second, random forest classifier verified the overall predictive accuracy of the model. Third, fuzzy c-means clustering assigned group membership based on the most informative MaFra factors.

Results

The most informative and parsimonious model selected through AIC included Placenta Previa, Pregnancy Induced Hypertension, Antibiotics, Cervix Length, Physical Exercise, Fetal Growth, Maternal Anxiety, Preeclampsia, Antihypertensives. The random forest classifier including only the most informative IU and EU factors achieved an overall accuracy of 81.08% and an AUC of 0.8122. The cluster analysis identified three groups of typical pregnant women, profiled on the basis of the most informative IU and EU risk factors from a lower to a higher degree of PTB risk, which paralleled time of birth delivery.

Conclusions

This study establishes a generalized methodology for building-up an evidence-based holistic risk assessment for PTB to be used in clinical practice. Relevant and essential factors were selected and were able to provide an accurate estimation of degree of PTB risk based on the most informative constellation of IU and EU factors.

Supplementary Information

The online version contains supplementary material available at (10.1186/s12884-021-03654-3).

Detection of small for gestational age in preterm prelabor rupture of membranes by Hadlock versus the Fetal Medicine Foundation growth charts

Objective

The primary outcome was to compare the diagnostic accuracy of neonatal small for gestational age (SGA) by the Hadlock and Fetal Medicine Foundation (FMF) charts in our cohort, followed by the ability to predict composite severe neonatal outcomes (SNO) in pregnancies with preterm prelabor rupture of membranes (PPROM).

Methods

This study was a secondary analysis of a prospective cohort of pregnancies with PPROM from 2015 to 2018, from 23 to 36 completed weeks of gestation. Sensitivity, specificity, and positive and negative predictive values for the primary and secondary outcomes of the Hadlock and FMF fetal charts were calculated. The discriminatory ability of each chart was compared using the area under the receiver’s operating curves of clinical characteristics.

Results

Of the 106 women who met the inclusion criteria, 48 (45%) were screened positive using the FMF fetal growth chart and 22 (21%) were screened positive using the Hadlock chart. SGA was diagnosed in 12 infants (11%). Both fetal growth charts had comparable diagnostic accuracies and were statistically significant predictors of SGA (Hadlock: area under the receiver operating characteristic curves [AUC], 0.76, risk ratio [RR], 7.6, 95% confidence interval [CI], 2.5–23; and FMF: AUC, 0.76 RR, 13.3 95%CI 1.8–99.3). Both growth standards were poor predictors of SNO.

Conclusion

The Hadlock and FMF fetal growth charts have a similar accuracy to predict SGA in pregnancies complicated by PPROM. The FMF fetal growth chart may result in a 2-fold increase in positive screens, potentially increasing fetal surveillance.

Preventing term stillbirth: benefits and limitations of using fetal growth reference charts

PURPOSE OF REVIEW

This review examines the variation in clinical practice with regards to ultrasound estimation of fetal weight, as well as calculation of fetal weight centiles.

RECENT FINDINGS

Placental dysfunction is associated with fetal smallness from intrauterine malnutrition as well as fetal disability and even stillbirth from hypoxemia. Although estimating fetal weight can be done accurately, the issue of which fetal weight centile chart should be used continues to be a contentious topic. The arguments against local fetal growth charts based on national borders and customization for variables known to be associated with disease are substantial. As for other human diseases such as hypertension and diabetes, there is a rationale for the use of an international fetal growth reference standard. Irrespective of the choice of fetal growth reference standard, a significant limitation of small for gestational age (SGA) detection programs to prevent stillbirth is that the majority of stillborn infants at term were not SGA at the time of demise.

SUMMARY

Placental dysfunction can present with SGA from malnutrition and/or stillbirth from hypoxemia depending on the gestational age of onset. Emerging data show that at term, fetal Doppler arterial redistribution is associated more strongly with perinatal death than fetal size. Properly conducted trials of the role for maternal characteristics, fetal size, placental biomarkers, and Doppler assessing fetal well-being are required urgently.

Factores de riesgo de parto pretérmino en Bogotá D.C., Colombia

Introducción. El parto pretérmino es aquel que ocurre antes de la semana 37 de gestación. Este tipo de parto se asocia a múltiples factores de riesgo, algunos de los cuales pueden ser prevenidos. En Colombia son escasos los estudios sobre los factores de riesgo asociados al parto pretérmino, de ahí la importancia de su análisis.Objetivo. Identificar los factores de riesgo para parto pretérmino en un grupo de gestantes de Bogotá D.C., Colombia.Materiales y métodos. Estudio de cohorte retrospectivo. La muestra estuvo compuesta por 452 pacientes que habían participado en un estudio primario y que ya habían dado a luz.Resultados. La prevalencia de parto pretérmino fue de 10.4% (IC95%: 7.60-13.20) y los factores de riesgo asociados fueron los siguientes: ser diagnosticada con preeclampsia severa, con un riesgo relativo (RR) de 7.4 (IC95%: 4.59-11.95); tener preeclampsia (severa y no severa), con un RR=5.1 (IC95%: 3.0-8.51), y ocurrencia de restricción del crecimiento intrauterino (RCIU), con un RR=4.4 (IC95%: 2.44-7.98).Conclusiones. De acuerdo con los hallazgos reportados en el presente estudio, es necesario planear e implementar estrategias y políticas públicas en Bogotá D.C. que promuevan mejores prácticas de atención prenatal que, a su vez, permitan la detección temprana de condiciones como la preeclampsia y la RCIU, lo que hará posible reducir la incidencia de partos pretérmino en la ciudad y utilizar la experiencia y resultados obtenidos en el resto del país.

Prediction of adverse perinatal outcome by fetal biometry: comparison of customized and population-based standards

OBJECTIVE

To compare the predictive performance of estimated fetal weight (EFW) percentiles, according to eight growth standards, to detect fetuses at risk for adverse perinatal outcome.

METHODS

This was a retrospective cohort study of 3437 African-American women. Population-based (Hadlock, INTERGROWTH-21^st , World Health Organization (WHO), Fetal Medicine Foundation (FMF)), ethnicity-specific (Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)), customized (Gestation-Related Optimal Weight (GROW)) and African-American customized (Perinatology Research Branch (PRB)/NICHD) growth standards were used to calculate EFW percentiles from the last available scan prior to delivery. Prediction performance indices and relative risk (RR) were calculated for EFW < 10^th and > 90^th percentiles, according to each standard, for individual and composite adverse perinatal outcomes. Sensitivity at a fixed (10%) false-positive rate (FPR) and partial (FPR < 10%) and full areas under the receiver-operating-characteristics curves (AUC) were compared between the standards.

RESULTS

Ten percent (341/3437) of neonates were classified as small-for-gestational age (SGA) at birth, and of these 16.4% (56/341) had at least one adverse perinatal outcome. SGA neonates had a 1.5-fold increased risk of any adverse perinatal outcome (P < 0.05). The screen-positive rate of EFW < 10^th percentile varied from 6.8% (NICHD) to 24.4% (FMF). EFW < 10^th percentile, according to all standards, was associated with an increased risk for each of the adverse perinatal outcomes considered (P < 0.05 for all). The highest RRs associated with EFW < 10^th percentile for each adverse outcome were 5.1 (95% CI, 2.1-12.3) for perinatal mortality (WHO); 5.0 (95% CI, 3.2-7.8) for perinatal hypoglycemia (NICHD); 3.4 (95% CI, 2.4-4.7) for mechanical ventilation (NICHD); 2.9 (95% CI, 1.8-4.6) for 5-min Apgar score < 7 (GROW); 2.7 (95% CI, 2.0-3.6) for neonatal intensive care unit (NICU) admission (NICHD); and 2.5 (95% CI, 1.9-3.1) for composite adverse perinatal outcome (NICHD). Although the RR CIs overlapped among all standards for each individual outcome, the RR of composite adverse perinatal outcome in pregnancies with EFW < 10^th percentile was higher according to the NICHD (2.46; 95% CI, 1.9-3.1) than the FMF (1.47; 95% CI, 1.2-1.8) standard. The sensitivity for composite adverse perinatal outcome varied substantially between standards, ranging from 15% for NICHD to 32% for FMF, due mostly to differences in FPR; this variation subsided when the FPR was set to the same value (10%). Analysis of AUC revealed significantly better performance for the prediction of perinatal mortality by the PRB/NICHD standard (AUC = 0.70) compared with the Hadlock (AUC = 0.66) and FMF (AUC = 0.64) standards. Evaluation of partial AUC (FPR < 10%) demonstrated that the INTERGROWTH-21^st standard performed better than the Hadlock standard for the prediction of NICU admission and mechanical ventilation (P < 0.05 for both). Although fetuses with EFW > 90^th percentile were also at risk for any adverse perinatal outcome according to the INTERGROWTH-21^st (RR = 1.4; 95% CI, 1.0-1.9) and Hadlock (RR = 1.7; 95% CI, 1.1-2.6) standards, many times fewer cases (2-5-fold lower sensitivity) were detected by using EFW > 90^th percentile, rather than EFW < 10^th percentile, in screening by these standards.

CONCLUSIONS

Fetuses with EFW < 10^th percentile or EFW > 90^th percentile were at increased risk of adverse perinatal outcomes according to all or some of the eight growth standards, respectively. The RR of a composite adverse perinatal outcome in pregnancies with EFW < 10^th percentile was higher for the most-stringent (NICHD) compared with the least-stringent (FMF) standard. The results of the complementary analysis of AUC suggest slightly improved detection of adverse perinatal outcome by more recent population-based (INTERGROWTH-21^st ) and customized (PRB/NICHD) standards compared with the Hadlock and FMF standards. Published 2019. This article is a U.S. Government work and is in the public domain in the USA.

Mediating roles of preterm birth and restricted fetal growth in the relationship between maternal education and infant mortality: A Danish population-based cohort study

BACKGROUND

Socioeconomic disparities in infant mortality have persisted for decades in high-income countries and may have become stronger in some populations. Therefore, new understandings of the mechanisms that underlie socioeconomic differences in infant deaths are essential for creating and implementing health initiatives to reduce these deaths. We aimed to explore whether and the extent to which preterm birth (PTB) and small for gestational age (SGA) at birth mediate the association between maternal education and infant mortality.

METHODS AND FINDINGS

We developed a population-based cohort study to include all 1,994,618 live singletons born in Denmark in 1981-2015. Infants were followed from birth until death, emigration, or the day before the first birthday, whichever came first. Maternal education at childbirth was categorized as low, medium, or high. An inverse probability weighting of marginal structural models was used to estimate the controlled direct effect (CDE) of maternal education on offspring infant mortality, further split into neonatal (0-27 days) and postneonatal (28-364 days) deaths, and portion eliminated (PE) by eliminating mediation by PTB and SGA. The proportion eliminated by eliminating mediation by PTB and SGA was reported if the mortality rate ratios (MRRs) of CDE and PE were in the same direction. The MRRs between maternal education and infant mortality were 1.63 (95% CI 1.48-1.80, P < 0.001) and 1.19 (95% CI 1.08-1.31, P < 0.001) for low and medium versus high education, respectively. The estimated proportions of these total associations eliminated by reducing PTB and SGA together were 55% (MRRPE = 1.27, 95% CI 1.15-1.40, P < 0.001) for low and 60% (MRRPE = 1.11, 95% CI 1.01-1.22, P = 0.037) for medium versus high education. The proportions eliminated by eliminating PTB and SGA separately were, respectively, 46% and 11% for low education (versus high education) and 48% and 13% for medium education (versus high education). PTB and SGA together contributed more to the association of maternal educational disparities with neonatal mortality (proportion eliminated: 75%-81%) than with postneonatal mortality (proportion eliminated: 21%-23%). Limitations of the study include the untestable assumption of no unmeasured confounders for the causal mediation analysis, and the limited generalizability of the findings to other countries with varying disparities in access and quality of perinatal healthcare.

CONCLUSIONS

PTB and SGA may play substantial roles in the relationship between low maternal education and infant mortality, especially for neonatal mortality. The mediating role of PTB appeared to be much stronger than that of SGA. Public health strategies aimed at reducing neonatal mortality in high-income countries may need to address socially related prenatal risk factors of PTB and impaired fetal growth. The substantial association of maternal education with postneonatal mortality not accounted for by PTB or SGA could reflect unaddressed educational disparities in infant care or other factors.

Preterm birth in evolutionary context: a predictive adaptive response?

Preterm birth is a significant public health problem worldwide, leading to substantial mortality in the newborn period, and a considerable burden of complications longer term, for affected infants and their carers. The fact that it is so common, and rates vary between different populations, raising the question of whether in some circumstances it might be an adaptive trait. In this review, we outline some of the evolutionary explanations put forward for preterm birth. We specifically address the hypothesis of the predictive adaptive response, setting it in the context of the Developmental Origins of Health and Disease, and explore the predictions that this hypothesis makes for the potential causes and consequences of preterm birth. We describe how preterm birth can be triggered by a range of adverse environmental factors, including nutrition, stress and relative socioeconomic status. Examining the literature for any associated longer-term phenotypic changes, we find no strong evidence for a marked temporal shift in the reproductive life-history trajectory, but more persuasive evidence for a re-programming of the cardiovascular and endocrine system, and a range of effects on neurodevelopment. Distinguishing between preterm birth as a predictive, rather than immediate adaptive response will depend on the demonstration of a positive effect of these alterations in developmental trajectories on reproductive fitness. This article is part of the theme issue 'Developing differences: early-life effects and evolutionary medicine'.

The implications of high carbon monoxide levels in early pregnancy for neonatal outcomes

OBJECTIVES

The aim of this study was to examine the implications of increased maternal Breath Carbon Monoxide (BCO) levels at the first antenatal visit for subsequent birthweight (BW) and neonatal outcomes.

STUDY DESIGN

Secondary analysis of a prospective, observational study. Pregnant women aged ≥18years who understood English were recruited (n=250). However, only women who delivered a normally formed baby weighing ≥500g were analysed (n=234). At the first antenatal visit, a research questionnaire was completed and a BCO test was performed. Obstetric and neonatal data computerised by midwives at the first antenatal visit and updated after delivery were also analysed.

RESULTS

Results from the receiver operating characteristic (ROC) curve indicated the highest combined sensitivity and specificity for smoking was observed at a BCO cut-off level of 3ppm (sensitivity 85%, specificity 90%). Of the 234 women, 53 (22.6%) had a BCO ≥3ppm but only 36 (15.4%) disclosed smoking to the midwife on routine questioning. A further 23 (9.8%) were classified as non-disclosers based on a research questionnaire and/or a BCO measurement ≥3ppm. No relationship was found between the self-reported number of cigarettes daily in early pregnancy and BW (r=0.05, p=0.78). However, an inverse relationship was found between maternal BCO levels and BW (r=-0.31, p<0.001). BCO levels ≥3ppm in early pregnancy were associated with an increased risk of emergency caesarean section, low birth weight, BW <25th centile, fetal distress and having two or more adverse pregnancy events (all p<0.05). Smoking non-disclosers had babies with decreased BWs (-400.1g, 95% CI 141.1-659.0g, p<0.001), and higher rates of BW <25th centile (56.5% versus 25.3%, p<0.001), small-for-gestational-age (21.7% versus 9.1%, p<0.001) and fetal distress (39.1% versus 16.0%, p<0.01) compared to non-smokers Non-disclosers at the first antenatal visit also had a 22% higher rate of having two or more adverse pregnancy events (p<0.05).

CONCLUSION

The results showed that an increased BCO level was associated with a lower BW and increased risk of adverse pregnancy and neonatal outcomes. This strengthens the case for universal BCO screening at the first antenatal visit. A high BCO reading should be an indication for referral to stop smoking services referral and close fetal surveillance.

An epigenetic association of malformations, adverse reproductive outcomes, and fetal origins hypothesis related effects

VACTERL, the prototype for associated congenital anomalies, also has connections with functional issues such as pregnancy losses, prematurity, growth delays, perinatal difficulties, and parental subfertility. This segues into a broader association with similar connections even in the absence of malformations. DNA methylation disturbances in the ovum are a likely cause, with epigenetic links to individual components and to folate effects before conception, explaining diverse fetal and placental findings and providing a link to fetal origin hypothesis-related effects. The association encompasses the following: (1) Pre- and periconceptual effects, with frequent fertility issues and occasional imprinting disorders. (2) Early malformations. (3) Adverse pregnancy outcomes (APOs), as above. (4) Developmental destabilization that resolves soon after birth. This potentiates other causes of association findings, introducing multiple confounders. (5) Long-term fetal origins hypothesis-related risks. The other findings are exceptional when the same malformations have Mendelian origins, supporting a distinct pathogenesis. Expressions are facilitated by one-carbon metabolic issues, maternal and fetal stress, and decreased embryo size. This may be one of the commonest causes of adverse reproductive outcomes, but multifactorial findings, variable onsets and phenotypes, and interactions with multiple confounders make recognition difficult. This association supports VACTERL as a continuum that includes isolated malformations, extends the fetal origins hypothesis, explains adverse effects linked to maternal obesity, and suggests possible interventions.

Customized growth charts: rationale, validation and clinical benefits

Appropriate standards for the assessment of fetal growth and birthweight are central to good clinical care, and have become even more important with increasing evidence that growth-related adverse outcomes are potentially avoidable. Standards need to be evidence based and validated against pregnancy outcome and able to demonstrate utility and effectiveness. A review of proposals by the Intergrowth consortium to adopt their single international standard finds little support for the claim that the cases that it identifies as small are due to malnutrition or stunting, and substantial evidence that there is normal physiologic variation between different countries and ethnic groups. It is possible that the one-size-fits-all standard ends up fitting no one and could be harmful if implemented. An alternative is the concept of country-specific charts that can improve the association between abnormal growth and adverse outcome. However, such standards ignore individual physiologic variation that affects fetal growth, which exists in any heterogeneous population and exceeds intercountry differences. It is therefore more logical to adjust for the characteristics of each mother, taking her ethnic origin and her height, weight, and parity into account, and to set a growth and birthweight standard for each pregnancy against which actual growth can be assessed. A customized standard better reflects adverse pregnancy outcome at both ends of the fetal size spectrum and has increased clinicians' confidence in growth assessment, while providing reassurance when abnormal size merely represents physiologic variation. Rollout in the United Kingdom has proceeded as part of the comprehensive Growth Assessment Protocol (GAP), and has resulted in a steady increase in antenatal detection of babies who are at risk because of fetal growth restriction. This in turn has been accompanied by a year-on-year drop in stillbirth rates to their lowest ever levels in England. A global version of customized growth charts with over 100 ethnic origin categories is being launched in 2018, and will provide an individualized, yet universally applicable, standard for fetal growth.

Evidence-based national guidelines for the management of suspected fetal growth restriction: comparison, consensus, and controversy

Small for gestational age is usually defined as an infant with a birthweight <10th centile for a population or customized standard. Fetal growth restriction refers to a fetus that has failed to reach its biological growth potential because of placental dysfunction. Small-for-gestational-age babies make up 28-45% of nonanomalous stillbirths, and have a higher chance of neurodevelopmental delay, childhood and adult obesity, and metabolic disease. The majority of small-for-gestational-age babies are not recognized before birth. Improved identification, accompanied by surveillance and timely delivery, is associated with reduction in small-for-gestational-age stillbirths. Internationally and regionally, detection of small for gestational age and management of fetal growth problems vary considerably. The aim of this review is to: summarize areas of consensus and controversy between recently published national guidelines on small for gestational age or fetal growth restriction; highlight any recent evidence that should be incorporated into existing guidelines; and identify future research priorities in this field. A search of MEDLINE, Google, and the International Guideline Library identified 6 national guidelines on management of pregnancies complicated by fetal growth restriction/small for gestational age published from 2010 onwards. There is general consensus between guidelines (at least 4 of 6 guidelines in agreement) in early pregnancy risk selection, and use of low-dose aspirin for women with major risk factors for placental insufficiency. All highlight the importance of smoking cessation to prevent small for gestational age. While there is consensus in recommending fundal height measurement in the third trimester, 3 specify the use of a customized growth chart, while 2 recommend McDonald rule. Routine third-trimester scanning is not recommended for small-for-gestational-age screening, while women with major risk factors should have serial scanning in the third trimester. Umbilical artery Doppler studies in suspected small-for-gestational-age pregnancies are universally advised, however there is inconsistency in the recommended frequency for growth scans after diagnosis of small for gestational age/fetal growth restriction (2-4 weekly). In late-onset fetal growth restriction (≥32 weeks) general consensus is to use cerebral Doppler studies to influence surveillance and/or delivery timing. Fetal surveillance methods (most recommend cardiotocography) and recommended timing of delivery vary. There is universal agreement on the use of corticosteroids before birth at <34 weeks, and general consensus on the use of magnesium sulfate for neuroprotection in early-onset fetal growth restriction (<32 weeks). Most guidelines advise using cardiotocography surveillance to plan delivery in fetal growth restriction <32 weeks. The recommended gestation at delivery for fetal growth restriction with absent and reversed end-diastolic velocity varies from 32 to ≥34 weeks and 30 to ≥34 weeks, respectively. Overall, where there is high-quality evidence from randomized controlled trials and meta-analyses, eg, use of umbilical artery Doppler and corticosteroids for delivery <34 weeks, there is a high degree of consistency between national small-for-gestational-age guidelines. This review discusses areas where there is potential for convergence between small-for-gestational-age guidelines based on existing randomized controlled trials of management of small-for-gestational-age pregnancies, and areas of controversy. Research priorities include assessing the utility of late third-trimester scanning to prevent major morbidity and mortality and to investigate the optimum timing of delivery in fetuses with late-onset fetal growth restriction and abnormal Doppler parameters. Prospective studies are needed to compare new international population ultrasound standards with those in current use.

Fetal growth standards: the NICHD fetal growth study approach in context with INTERGROWTH-21st and the World Health Organization Multicentre Growth Reference Study

Three recently completed longitudinal cohort studies have developed intrauterine fetal growth charts, one in the United States and two international. This expert review compares and contrasts the Eunice Kennedy Shriver National Institute of Child Health and Human Development Fetal Growth Studies, INTERGROWTH-21st and World Health Organization Multicentre Growth Reference Study conclusions in light of differences in aims, sampling frames, and analytical approaches. An area of controversy is whether a single growth reference is representative of growth, regardless of ethnic or country origin. The INTERGROWTH and World Health Organization Fetal studies used a similar approach as the World Health Organization Multicentre Growth Reference Study for infants and children, the aim of which was to create a single international reference for the best physiological growth for children aged 0-5 years. INTERGROWTH made the same assumption (ie, that there would be no differences internationally among countries or racial/ethnic groups in fetal growth when conditions were optimal). INTERGROWTH found differences in crown-rump length and head circumference among countries but interpreted the differences as not meaningful and presented a pooled standard. The World Health Organization Multicentre Growth Reference Study was designed to create a pooled reference, although they evaluated for and presented country differences, along with discussion of the implications. The Eunice Kennedy Shriver National Institute of Child Health and Human Development Study was designed to assess whether racial/ethnic-specific fetal growth standards were needed, in recognition of the fact that fetal size is commonly estimated from dimensions (head circumference, abdominal circumference, and femur length) in which there are known differences in children and adults of differing racial/ethnic groups. A pooled standard would be derived if no racial/ethnic differences were found. Highly statistically significant racial/ethnic differences in fetal growth were found resulting in the publication of racial/ethnic-specific derived standards. Despite all 3 studies including low-risk status women, the percentiles for fetal dimensions and estimated fetal weight varied among the studies. Specifically, at 39 weeks, the 50th percentile for estimated fetal weight was 3502 g for whites, 3330 g for Hispanics, 3263 g for Asians, and 3256 for blacks in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Study, compared with 3186 g for INTERGROWTH and 3403 g for World Health Organization Multicentre Growth Reference Study. When applying these standards to a clinical population, it is important to be aware that different percentages of small- and large-for-gestational-age fetuses will be identified. Also, it may be necessary to use more restrictive cut points, such as the 2.5th or 97.5th, for small-for-gestational-age or large-for-gestational-age fetuses, respectively. Ideally, a comparison of diagnostic accuracy, or misclassification rates, of small-for-gestational-age and large-for-gestational-age fetuses in relation to morbidity and mortality using different criteria is necessary to make recommendations and remains an important data gap. Identification of the appropriate percentile cutoffs in relation to neonatal morbidity and mortality is needed in local populations, depending on which fetal growth chart is used. On a final point, assessment of fetal growth with a one-time measurement remains standard clinical practice, despite recognition that a single measurement can indicate only size. Ultimately, it is knowledge about fetal growth in addition to other factors and clinical judgment that should trigger intervention.

Customized vs INTERGROWTH-21st standards for the assessment of birthweight and stillbirth risk at term

BACKGROUND

Fetal growth abnormalities are linked to stillbirth and other adverse pregnancy outcomes, and use of the correct birthweight standard is essential for accurate assessment of growth status and perinatal risk.

OBJECTIVE

Two competing, conceptually opposite birthweight standards are currently being implemented internationally: customized gestation-related optimal weight (GROW) and INTERGROWTH-21^st. We wanted to compare their performance when applied to a multiethnic international cohort, and evaluate their usefulness in the assessment of stillbirth risk at term.

STUDY DESIGN

We analyzed routinely collected maternity data from 10 countries with a total of 1.25 million term pregnancies in their respective main ethnic groups. The 2 standards were applied to determine small for gestational age (SGA) and large for gestational age (LGA) rates, with associated relative risk and population-attributable risk of stillbirth. The customized standard (GROW) was based on the term optimal weight adjusted for maternal height, weight, parity, and ethnic origin, while INTERGROWTH-21^st was a fixed standard derived from a multiethnic cohort of low-risk pregnancies.

RESULTS

The customized standard showed an average SGA rate of 10.5% (range 10.1-12.7) and LGA rate of 9.5% (range 7.3-9.9) for the set of cohorts. In contrast, there was a wide variation in SGA and LGA rates with INTERGROWTH-21^st, with an average SGA rate of 4.4% (range 3.1-16.8) and LGA rate of 20.6% (range 5.1-27.5). This variation in INTERGROWTH-21^st SGA and LGA rates was correlated closely (R = ±0.98) to the birthweights predicted for the 10 country cohorts by the customized method to derive term optimal weight, suggesting that they were mostly due to physiological variation in birthweight. Of the 10.5% of cases defined as SGA according to the customized standard, 4.3% were also SGA by INTERGROWTH-21^st and had a relative risk of 3.5 (95% confidence interval, 3.1-4.1) for stillbirth. A further 6.3% (60% of the whole customized SGA) were not SGA by INTERGROWTH-21^st, and had a relative risk of 1.9 (95% confidence interval, 3.1-4.1) for stillbirth. An additional 0.2% of cases were SGA by INTERGROWTH-21^st only, and had no increased risk of stillbirth. At the other end, customized assessment classified 9.5% of births as large for gestational age, most of which (9.0%) were also LGA by the INTERGROWTH-21^st standard. INTERGROWTH-21^st identified a further 11.6% as LGA, which, however, had a reduced risk of stillbirth (relative risk, 0.6; 95% confidence interval, 0.5-0.7).

CONCLUSION

Customized assessment resulted in increased identification of small for gestational age and stillbirth risk, while the wide variation in SGA rates using the INTERGROWTH-21^st standard appeared to mostly reflect differences in physiological pregnancy characteristics in the 10 maternity populations.

New birthweight charts according to parity and type of delivery for the Spanish population

OBJECTIVE

Birthweight by gestational age charts enable fetal growth to be evaluated in a specific population. Given that maternal profile and obstetric practice have undergone a remarkable change over the past few decades in Spain, this paper presents new Spanish reference percentile charts stratified by gender, parity and type of delivery. They have been prepared with data from the 2010-2014 period of the Spanish Birth Statistics Bulletin.

METHODS

Reference charts have been prepared using the LMS method, corresponding to 1,428,769 single, live births born to Spanish mothers. Percentile values and mean birth weight are compared among newborns according to gender, parity and type of delivery.

RESULTS

Newborns to primiparous mothers show significantly lower birthweight than those born to multiparous mothers (p<0.036). Caesarean section was associated with a substantially lower birthweight in preterm births (p<0.048), and with a substantially higher birthweight for full-term deliveries (p<0.030). Prevalence of small for gestational age is significantly higher in newborns born by Caesarean section, both in primiparous (p<0.08) and multiparous mothers (p<0.027) and, conversely, the prevalence of large for gestational age among full-term births is again greater both in primiparous (p<0.035) and in multiparous mothers (p<0.007).

CONCLUSIONS

Results support the consideration of establishing parity and type of delivery-specific birthweight references. These new charts enable a better evaluation of the impact of the demographic, reproductive and obstetric trends currently in Spain on fetal growth.

INTERGROWTH-21st vs customized birthweight standards for identification of perinatal mortality and morbidity

BACKGROUND

The recently published INTERGROWTH-21st Project international population standard for newborn size is intended for global use, but its ability to identify small infants at risk of adverse outcomes in a general obstetric population has not been reported.

OBJECTIVE

The objective of the study was to compare adverse neonatal outcomes among small-for-gestational-age (SGA) infants between the INTERGROWTH-21st standard and a customized birthweight standard (accounting for maternal characteristics of height, weight, parity, and ethnicity). We hypothesized that in a multiethnic general obstetric population in Auckland, New Zealand, a customized birthweight standard would better identify SGA infants at-risk of neonatal morbidity/mortality and stillbirth than the INTERGROWTH-21st standard.

STUDY DESIGN

Using prospectively gathered maternity data from a general obstetric population in Auckland, New Zealand, from 2006 to 2013 (n = 53,484 births at ≥ 33 weeks), infants were classified as SGA (birthweight < 10th centile) by INTERGROWTH-21st and customized standards. Infants were further categorized as SGA by both criteria, INTERGROWTH-21st only, customized only, or not SGA (met neither criteria). Composite adverse neonatal outcome was defined as neonatal death, neonatal intensive care admission > 48 hours, or ventilation > 4 hours or 5-minute Apgar score < 7. Relative risks for primary outcomes were estimated using modified Poisson regression, with the non-SGA group as the referent.

RESULTS

Incidence of SGA was 4.5% by INTERGROWTH-21st and 11.6% by customized standard. Compared with those not SGA, infants identified as small for gestational age by both criteria had the highest risk of adverse neonatal outcome (relative risk [RR], 4.1, 95% confidence interval [CI], 3.7-4.6) and stillbirth (RR, 8.3, 95% CI, 5.1-13.4). Infants SGA by customized standard only (n = 4015) had an increased risk of adverse neonatal outcome (RR, 2.0, 95% CI, 1.8-2.2) and stillbirth (RR, 3.0, 95% CI, 1.7-5.3). Few infants were identified as SGA by INTERGROWTH-21st only (n = 172), and risks of adverse neonatal outcome and stillbirth were not increased. Findings were unchanged when analyses were limited to term infants (n = 50,739). The INTERGROWTH-21st standard identified more Indian (12.8%) and Asian (5.8%) but fewer European (3.0%) and Pacific (2.9%) infants as SGA (P < .01). Customized criteria identified more than 3 times as many SGA infants among Maori (14.5%), Pacific (13.5%), and European (11.2%) infants and twice as many among Asian (10.3%) infants (P<0.01) compared with INTERGROWTH-21st criteria. The majority of SGA infants by INTERGROWTH-21st only were born to Indian and Asian mothers (95.4%).

CONCLUSIONS

In our general obstetric population, birthweight customization identified more SGA infants at risk of perinatal mortality and morbidity compared with the INTERGROWTH-21st standard. The INTERGROWTH-21st standard failed to detect many at-risk SGA infants, particularly among ethnic groups with larger maternal size while disproportionately identifying higher rates of SGA among those with smaller maternal size. Local validation is needed prior to implementation of the INTERGROWTH-21st standard to avoid misclassification of infant birth size.

New Japanese neonatal anthropometric charts for gestational age at birth

BACKGROUND

More than 10 years have passed since the previous Japanese neonatal growth charts were published, therefore the aim of this study was to develop an updated set of Japanese neonatal growth charts.

METHODS

We used data from the registry database of the Japan Society of Obstetrics and Gynecology from 2003 until 2005. A total of 150,471 singleton live births without stillbirth or severe congenital malformation were enrolled in the preliminary analysis. It was found that the distribution of the 10th centile charts based on these subjects was skewed toward lower birthweight for preterm infants, because of the significantly lower birthweight in the 10th centile in neonates delivered by cesarean section than those delivered vaginally. Therefore, the data of subjects delivered by cesarean section were also excluded.

RESULTS

Finally, 104,748 singleton vaginal births at 22-41 weeks of gestation were used to construct a new set of Japanese neonatal anthropometric charts. The birthweight chart is parity and sex specific. The differences between the Japanese fetal growth chart and the new neonatal birthweight chart were small.

CONCLUSION

The present new neonatal anthropometric charts may reveal unrestricted growth pattern mimicking fetal growth. Use of these charts may result in recognition of abnormal fetal growth and risk in preterm infants. Further studies are needed to evaluate the risk for adverse neonatal and long-term outcome among small-for-gestational-age infants using these neonatal charts.

Birth weight ratio as an alternative to birth weight percentile to express infant weight in research and clinical practice: a nationwide cohort study

Objective. To compare birth weight ratio and birth weight percentile to express infant weight when assessing pregnancy outcome. Study Design. We performed a national cohort study. Birth weight ratio was calculated as the observed birth weight divided by the median birth weight for gestational age. The discriminative ability of birth weight ratio and birth weight percentile to identify infants at risk of perinatal death (fetal death and neonatal death) or adverse pregnancy outcome (perinatal death + severe neonatal morbidity) was compared using the area under the curve. Outcomes were expressed stratified by gestational age at delivery separate for birth weight ratio and birth weight percentile. Results. We studied 1,299,244 pregnant women, with an overall perinatal death rate of 0.62%. Birth weight ratio and birth weight percentile have equivalent overall discriminative performance for perinatal death and adverse perinatal outcome. In late preterm infants (33(+0)-36(+6) weeks), birth weight ratio has better discriminative ability than birth weight percentile for perinatal death (0.68 versus 0.63, P  0.01) or adverse pregnancy outcome (0.67 versus 0.60, P < 0.001). Conclusion. Birth weight ratio is a potentially valuable instrument to identify infants at risk of perinatal death and adverse pregnancy outcome and provides several advantages for use in research and clinical practice. Moreover, it allows comparison of groups with different average birth weights.

The nexus of prematurity, birth defects, and intrauterine growth restriction: a role for plac1-regulated pathways

Epidemiological studies have demonstrated an increased prevalence of birth defects and intrauterine growth restriction (IUGR) among infants born prematurely suggesting they share common biological determinants. The identification of key regulatory pathways contributing to this nexus is essential to ongoing efforts to develop effective intervention strategies. Plac1 is a paternally imprinted and X-linked gene that conforms to this paradigm. Examination of a mutant mouse model has confirmed that Plac1 is essential for normal placental development and function. Moreover, it is expressed throughout the developing embryo indicating that it also has broad relevance to embryogenesis. Most notably, its absence in the developing embryo is associated with abnormal brain development and an increased risk of lethal, postnatal hydrocephalus identifying it as a novel, X-linked determinant of brain development. The essential and non-redundant roles of Plac1 in placental and neurological development represent a novel regulatory paradigm for embryonic growth and pregnancy maintenance. Regulatory pathways influenced, in part, by Plac1 are likely to contribute to the observed nexus of IUGR, prematurity, and birth defects.

Application of a global reference for fetal-weight and birthweight percentiles in predicting infant mortality

OBJECTIVE

To determine whether the recently published A global reference for fetal-weight and birthweight percentiles (Global Reference) improves small- (SGA), appropriate- (AGA), and large-for-gestational-age (LGA) definitions in predicting infant mortality.

DESIGN

Population-based cohort study.

SETTING

The US Linked Livebirth and Infant Death records between 1995 and 2004.

POPULATION

Singleton births with birthweight >500 g born at 24-41 weeks of gestation.

METHODS

We compared infant mortality rates of SGA, AGA, and LGA infants classified by three different references: the Global Reference; a commonly used birthweight reference; and Hadlock's ultrasound reference.

MAIN OUTCOME MEASURES

Infant mortality rates.

RESULTS

Among 33 997 719 eligible liveborn singleton births, 25% of preterm and 9% of term infants were classified differently for SGA, AGA, and LGA by the Global Reference and the birthweight reference. The Global Reference indicated higher mortality rates in preterm SGA and preterm LGA infants than the birthweight reference. The mortality rate was considerably higher in infants classified as preterm SGA by the Global Reference but not by the birthweight reference, compared with the corresponding infants classified by the birthweight reference but not by the Global Reference (105.7 versus 12.9 per 1000, RR 8.17, 95% CI 7.38-9.06). Yet, the differences in mortality rates were much smaller in term infants than in preterm infants. Black infants had a particularly higher mortality rate than other races in AGA and LGA preterm and term infants.

CONCLUSIONS

In respect to the commonly used birthweight reference, the Global Reference increases the identification of infant deaths by improved classification of abnormal newborn size at birth, and these advantages were more obvious in preterm than in term infants.

Recurrence of small-for-gestational-age pregnancy: analysis of first and subsequent singleton pregnancies in The Netherlands

OBJECTIVE

Small-for-gestational-age (SGA) neonates are at increased risk of adverse pregnancy outcome. Our objective was to study the recurrence rate of SGA in subsequent pregnancies.

STUDY DESIGN

A prospective national cohort study of all women with a structurally normal first and subsequent singleton pregnancy from 1999-2007. SGA was defined as birthweight <5th percentile for gestation. We compared the incidence and recurrence rate of SGA for women in total and with and without a hypertensive disorder (HTD) in their first pregnancy. Moreover, we assessed the association between gestational age at first delivery and SGA recurrence.

RESULTS

We studied 259,481 pregnant women, of whom 12,943 women (5.0%) had an SGA neonate in their first pregnancy. The risk of SGA in the second pregnancy was higher in women with a previous SGA neonate than for women without a previous SGA neonate (23% vs 3.4%; adjusted odds ratio, 8.1; 95% confidence interval, 7.8-8.5) and present in both women with and without an HTD in pregnancy. In women without an HTD, the increased recurrence risk was independent of the gestational age at delivery in the index pregnancy; whereas in women with an HTD, this recurrence risk was increased only when the woman with the index delivery delivered at >32 weeks' gestation.

CONCLUSION

Women with SGA in their first pregnancy have a strongly increased risk of SGA in the subsequent pregnancy and first pregnancy SGA delivers a significant contribution to the total number of second pregnancy SGA cases.

Growth monitoring of low birthweight infants: what references to use?

Growth charts are the mainstay of monitoring growth in babies who were born small or preterm. A variety of different charts are available, each with specific limitations. Most birthweight centile charts underestimate growth restriction in preterm babies and there are few good charts for monitoring longitudinal growth in preterm babies; it is important to be aware of the limitations of using cross-sectional data for monitoring longitudinal growth. Customised centile charts of fetal growth are used increasingly for antenatal monitoring for small-for-gestational age fetuses despite a lack of robust evidence. It is also unclear whether customised centile charts should be used for assessing birthweight, particularly in babies born at term. Faltering post-natal growth in preterm babies is very common but need not be universal with close attention to nutrition. Monitoring of growth trajectories through infancy following either fetal growth restriction or post-natal faltering growth is important to ensure proportional growth, particularly during periods of accelerated growth. This review will discuss these issues in the context of current practice in Australia and New Zealand.

Low Birth Weight due to Intrauterine Growth Restriction and/or Preterm Birth: Effects on Nephron Number and Long-Term Renal Health

Epidemiological studies have clearly demonstrated a strong association between low birth weight and long-term renal disease. A potential mediator of this long-term risk is a reduction in nephron endowment in the low birth weight infant at the beginning of life. Importantly, nephrons are only formed early in life; during normal gestation, nephrogenesis is complete by about 32–36 weeks, with no new nephrons formed after this time during the lifetime of the individual. Hence, given that a loss of a critical number of nephrons is the hallmark of renal disease, an increased severity and acceleration of renal disease is likely when the number of nephrons is already reduced prior to disease onset. Low birth weight can result from intrauterine growth restriction (IUGR) or preterm birth; a high proportion of babies born prematurely also exhibit IUGR. In this paper, we describe how IUGR and preterm birth adversely impact on nephrogenesis and how a subsequent reduced nephron endowment at the beginning of life may lead to long-term risk of renal disease, but not necessarily hypertension.

Neonatal factors associated with alteration of palatal morphology in very preterm children: the EPIPAGE cohort study

BACKGROUND

Altered palatal morphology has been observed among some preterm children, with possible consequences on chewing, speaking and esthetics, but determinants remain unknown.

AIM

To explore the role of neonatal characteristics and neuromotor dysfunction in alteration of palatal morphology at 5 years of age in very preterm children.

STUDY DESIGN

Prospective population-based cohort study.

SUBJECTS

1711 children born between 22 and 32 weeks of gestation in 1997 or born between 22 and 26 weeks of gestation in 1998 were included in the study. They all had a medical examination at 5 years of age.

OUTCOME MEASURES

Alteration of palatal morphology.

RESULTS

The prevalence of altered palatal morphology was 3.7% in the overall sample, 5.1% among boys and 2.2% among girls (adj OR: 2.52; 95%CI: 1.44-4.42). The risk for altered palatal morphology was higher for lower gestational age (adj OR: 0.85; 95%CI: 0.74-0.97 per week), small-for-gestational age children (adj OR: 2.11; 95%CI: 1.20-3.72) or children intubated for more than 28 days (adj OR: 3.16; 95%CI: 1.11-8.98). Altered palatal morphology was more common in case of cerebral palsy or moderate neuromotor dysfunction assessed at 5 years. Results were basically the same when neuromotor dysfunction was taken into account, except for intubation.

CONCLUSION

Male sex, low gestational age, small-for-gestational age and long intubation have been identified as probable neonatal risk factors for alteration of palatal morphology at 5 years of age in very preterm children. Further studies are needed to confirm these results.

Neonatal mortality risk associated with preterm birth in East Africa, adjusted by weight for gestational age: individual participant level meta-analysis

BACKGROUND

Low birth weight and prematurity are amongst the strongest predictors of neonatal death. However, the extent to which they act independently is poorly understood. Our objective was to estimate the neonatal mortality risk associated with preterm birth when stratified by weight for gestational age in the high mortality setting of East Africa.

METHODS AND FINDINGS

Members and collaborators of the Malaria and the MARCH Centers, at the London School of Hygiene & Tropical Medicine, were contacted and protocols reviewed for East African studies that measured (1) birth weight, (2) gestational age at birth using antenatal ultrasound or neonatal assessment, and (3) neonatal mortality. Ten datasets were identified and four met the inclusion criteria. The four datasets (from Uganda, Kenya, and two from Tanzania) contained 5,727 births recorded between 1999-2010. 4,843 births had complete outcome data and were included in an individual participant level meta-analysis. 99% of 445 low birth weight (< 2,500 g) babies were either preterm (< 37 weeks gestation) or small for gestational age (below tenth percentile of weight for gestational age). 52% of 87 neonatal deaths occurred in preterm or small for gestational age babies. Babies born < 34 weeks gestation had the highest odds of death compared to term babies (odds ratio [OR] 58.7 [95% CI 28.4-121.4]), with little difference when stratified by weight for gestational age. Babies born 34-36 weeks gestation with appropriate weight for gestational age had just three times the likelihood of neonatal death compared to babies born term, (OR 3.2 [95% CI 1.0-10.7]), but the likelihood for babies born 34-36 weeks who were also small for gestational age was 20 times higher (OR 19.8 [95% CI 8.3-47.4]). Only 1% of babies were born moderately premature and small for gestational age, but this group suffered 8% of deaths. Individual level data on newborns are scarce in East Africa; potential biases arising due to the non-systematic selection of the individual studies, or due to the methods applied for estimating gestational age, are discussed.

CONCLUSIONS

Moderately preterm babies who are also small for gestational age experience a considerably increased likelihood of neonatal death in East Africa.

Clinical strategies for improving the detection of fetal growth restriction

The single most important condition affecting the viable fetus is intrauterine growth retardation (IUGR). IUGR is a common condition, affecting about 10% to 15% of the general maternity population. Despite its importance and relatively high prevalence, IUGR detection is poor. This article will focus on how to improve on IUGR detection.

Approximately one-third of medically indicated late preterm births are complicated by fetal growth restriction

OBJECTIVE

The purpose of this study was to report the frequency of fetal growth restriction (FGR) based on indication for late preterm birth (LPTB).

STUDY DESIGN

Singleton live born pregnancies that were delivered from 34-36 weeks 6 days of gestation over a 1-year period at a tertiary care medical center were studied. Indications for delivery were categorized as spontaneous (spontaneous preterm birth or premature rupture of membranes), medically indicated, or elective. A customized birthweight percentile was calculated for each pregnancy; the rate of FGR was compared based on indication for LPTB.

RESULTS

There were 482 LPTBs that met all criteria. Customized birthweight percentiles (median; interquartile range) were different among groups (spontaneous, 45.5%; 20.8-73.5%; medically indicated, 26.9%; 4.1-63.6%; elective, 45.9%; 22.2-78.3%; P = .001). The rate of FGR was also different among groups (spontaneous, 13%; medically indicated, 32%; elective, 21%; P = .001).

CONCLUSION

With the use of customized birthweight standards, we found that FGR complicated approximately one-third of all cases of medically indicated LPTB.