The relationship between intrauterine growth restriction and preterm delivery: an empirical approach using data from a European case-control study

Association between fetal growth restriction and stillbirth in twin compared with singleton pregnancies

OBJECTIVES

Twin pregnancies are at higher risk of stillbirth compared to singletons. Fetal growth restriction (FGR) is a major cause of perinatal mortality, but its impact on twins vs singletons remains unclear. The primary objective of this study was to investigate the association of FGR and small-for-gestational age (SGA) with stillbirth in twin compared with singleton pregnancies. A secondary objective was to assess these associations stratified by gestational age at delivery. Furthermore, we aimed to compare the associations of FGR and SGA with stillbirth in twin pregnancies using twin-specific vs singleton birth-weight charts, stratified by chorionicity.

METHODS

This was a retrospective cross-sectional study of pregnancies receiving obstetric care and giving birth between 1999 and 2022 at St George's Hospital, London, UK. The exclusion criteria included triplet and higher-order pregnancies, those resulting in miscarriage or live birth at ≤ 23 + 6 weeks, termination of pregnancy and missing data regarding birth weight or gestational age at birth. Birth-weight data were collected and FGR and SGA were defined as birth weight <5th and <10th centiles, respectively. While standard logistic regression was used for singleton pregnancies, the association of FGR and SGA with stillbirth in twin pregnancies was investigated using mixed-effects logistic regression models. For twin pregnancies, intercepts were allowed to vary for twin pairs to account for intertwin dependency. Analyses were stratified by gestational age at delivery and chorionicity. Statistical significance was set at P ≤ 0.001.

RESULTS

The study included 95 342 singleton and 3576 twin pregnancies. There were 494 (0.52%) stillbirths in singleton and 41 (1.15%) stillbirths in twin pregnancies (17 dichorionic and 24 monochorionic). SGA and FGR were associated significantly with stillbirth in singleton pregnancies across all gestational ages at delivery: the odds ratios (ORs) for SGA and FGR were 2.36 ((95% CI, 1.78-3.13), P < 0.001) and 2.67 ((95% CI, 2.02-3.55), P < 0.001), respectively, for delivery before 32 weeks; 2.70 ((95% CI, 1.71-4.31), P < 0.001) and 2.82 ((95% CI, 1.78-4.47), P < 0.001), respectively, for delivery between 32 and 36 weeks; and 3.85 ((95% CI, 2.83-5.21), P < 0.001) and 4.43 ((95% CI, 3.16-6.12), P < 0.001), respectively, for delivery after 36 weeks. In twin pregnancies, when stratified by gestational age at delivery, both SGA and FGR determined by twin-specific birth-weight charts were associated with increased odds of stillbirth for those delivered before 32 weeks (SGA: OR, 3.87 (95% CI, 1.56-9.50), P = 0.003 and FGR: OR, 5.26 (95% CI, 2.11-13.01), P = 0.001), those delivered between 32 and 36 weeks (SGA: OR, 6.67 (95% CI, 2.11-20.41), P = 0.001 and FGR: OR, 9.54 (95% CI, 3.01-29.40), P < 0.001) and those delivered beyond 36 weeks (SGA: OR, 12.68 (95% CI, 2.47-58.15), P = 0.001 and FGR: OR, 23.84 (95% CI, 4.62-110.25), P < 0.001). However, the association of stillbirth with SGA and FGR in twin pregnancies was non-significant when diagnosis was based on singleton charts (before 32 weeks: SGA, P = 0.014 and FGR, P = 0.005; 32-36 weeks: SGA, P = 0.036 and FGR, P = 0.008; after 36 weeks: SGA, P = 0.080 and FGR, P = 0.063).

CONCLUSION

Our study demonstrates that SGA and, especially, FGR are associated significantly with an increased risk of stillbirth across all gestational ages in singleton pregnancies, and in twin pregnancies when twin-specific birth-weight charts are used. © 2024 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Temporal Dynamics of Oxidative Stress and Inflammation in Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is the most common lung complication of prematurity. Despite extensive research, our understanding of its pathophysiology remains limited, as reflected by the stable prevalence of BPD. Prematurity is the primary risk factor for BPD, with oxidative stress (OS) and inflammation playing significant roles and being closely linked to premature birth. Understanding the interplay and temporal relationship between OS and inflammation is crucial for developing new treatments for BPD. Animal studies suggest that OS and inflammation can exacerbate each other. Clinical trials focusing solely on antioxidants or anti-inflammatory therapies have been unsuccessful. In contrast, vitamin A and caffeine, with antioxidant and anti-inflammatory properties, have shown some efficacy, reducing BPD by about 10%. However, more than one-third of very preterm infants still suffer from BPD. New therapeutic agents are needed. A novel tripeptide, N-acetyl-lysyltyrosylcysteine amide (KYC), is a reversible myeloperoxidase inhibitor and a systems pharmacology agent. It reduces BPD severity by inhibiting MPO, enhancing antioxidative proteins, and alleviating endoplasmic reticulum stress and cellular senescence in a hyperoxia rat model. KYC represents a promising new approach to BPD treatment.

The Influence of Pulmonary Arterial Hypertension In Pregnancy: A Review

Pulmonary arterial hypertension (PAH) is a severe condition characterized by increased pulmonary vascular resistance and right ventricular failure. This review examines the intersection of PAH and pregnancy, highlighting the significant physiological, hemodynamic, and hormonal changes that exacerbate PAH during gestation. Pregnancy is contraindicated in PAH patients due to high maternal and fetal morbidity and mortality rates. However, some patients choose to continue their pregnancies, necessitating a comprehensive understanding of the implications and management strategies. Effective management of PAH in pregnant patients involves individualized treatment plans. Prepartum management focuses on optimizing therapy and monitoring hemodynamic status. Prostacyclin analogs and phosphodiesterase inhibitors are commonly used, though their safety profiles require further investigation. Intrapartum management prioritizes preventing right ventricular failure, utilizing therapies such as intravenous epoprostenol, inhaled iloprost, and inhaled nitric oxide. Managing PAH in pregnancy requires careful planning, continuous monitoring, and tailored therapeutic strategies to navigate the complex interplay of physiological changes and mitigate risks. Future research should focus on elucidating the pathophysiology of PAH during pregnancy and developing safer, more effective treatments to improve maternal and fetal outcomes.

Association between risk of infant death and birth-weight z scores according to gestational age: A nationwide study using the Finnish Medical Birth Register

OBJECTIVE

To investigate the association between infant mortality and birth weight using estimated fetal weight (EFW) versus birth-weight charts, by gestational age (GA).

METHODS

This nationwide population-based study used data from the Finnish Medical Birth Register from 2006 to 2016 on non-malformed singleton live births at 24-41+6 weeks of gestation (N = 563 630). The outcome was death in the first year of life. Mortality risks by birth-weight z score, defined as a continuous variable using Maršál's EFW and Sankilampi's birth-weight charts, were assessed using generalized additive models by GA (24-27+6, 28-31+6, 32-36+6, 37-38+6, 39-41+6 weeks). We calculated z score thresholds associated with a two- and three-fold increased risk of infant death compared with newborns with a birth weight between 0 and 0.675 standard deviations.

RESULTS

The z score thresholds (with corresponding centiles in parentheses) associated with a two-fold increase in infant mortality were: -3.43 (<0.1) at 24-27+6 weeks, -3.46 (<0.1) at 28-31+6 weeks, -1.29 (9.9) at 32-36+6 weeks, -1.18 (11.9) at 37-38+6 weeks, and - 1.34 (9.0) at 39-41+6 weeks according to the EFW chart. These values were - 2.43 (0.8), -2.62 (0.4), -1.34 (9.0), -1.37 (8.5), and - 1.43 (7.6) according to the birth-weight chart.

CONCLUSION

The association between birth weight and infant mortality varies by GA whichever chart is used, suggesting that different thresholds for the screening of growth anomalies could be used across GA to identify high-risk newborns.

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.

Maternal tadalafil treatment does not increase uterine artery blood flow or oxygen delivery in the pregnant ewe

Increasing placental perfusion (PP) could improve outcomes of growth-restricted fetuses. One way of increasing PP may be by using phosphodiesterase (PDE)-5 inhibitors, which induce vasodilatation of vascular beds. We used a combination of clinically relevant magnetic resonance imaging (MRI) techniques to characterize the impact that tadalafil infusion has on maternal, placental and fetal circulations. At 116-117 days' gestational age (dGA; term, 150 days), pregnant ewes (n = 6) underwent fetal catheterization surgery. At 120-123 dGA ewes were anaesthetized and MRI scans were performed during three acquisition windows: a basal state and then ∼15-75 min (TAD 1) and ∼75-135 min (TAD 2) post maternal administration (24 mg; intravenous bolus) of tadalafil. Phase contrast MRI and T2 oximetry were used to measure blood flow and oxygen delivery. Placental diffusion and PP were assessed using the Diffusion-Relaxation Combined Imaging for Detailed Placental Evaluation-'DECIDE' technique. Uterine artery (UtA) blood flow when normalized to maternal left ventricular cardiac output (LVCO) was reduced in both TAD periods. DECIDE imaging found no impact of tadalafil on placental diffusivity or fetoplacental blood volume fraction. Maternal-placental blood volume fraction was increased in the TAD 2 period. FetalD O 2 ${D_{{{\mathrm{O}}_2}}}$ andV ̇ O 2 ${\dot V_{{{\mathrm{O}}_2}}}$ were not affected by maternal tadalafil administration. Maternal tadalafil administration did not increase UtA blood flow and thus may not be an effective vasodilator at the level of the UtAs. The increased maternal-placental blood volume fraction may indicate local vasodilatation of the maternal intervillous space, which may have compensated for the reduced proportion of UtAD O 2 ${D_{{{\mathrm{O}}_2}}}$ .

Etiologically Based Functional Taxonomy of the Preterm Birth Syndrome

Preterm birth (PTB) is a complex syndrome traditionally defined by a single parameter, namely, gestational age at birth (ie, ˂37 weeks). This approach has limitations for clinical usefulness and may explain the lack of progress in identifying cause-specific effective interventions. The authors offer a framework for a functional taxonomy of PTB based on (1) conceptual principles established a priori; (2) known etiologic factors; (3) specific, prospectively identified obstetric and neonatal clinical phenotypes; and (4) postnatal follow-up of growth and development up to 2 years of age. This taxonomy includes maternal, placental, and fetal conditions routinely recorded in data collection systems.

Adverse Skeletal Muscle Adaptations in Individuals Born Preterm-A Comprehensive Review

Infants born preterm face an increased risk of deleterious effects on lung and brain health that can significantly alter long-term function and quality of life and even lead to death. Moreover, preterm birth is also associated with a heightened risk of diabetes and obesity later in life, leading to an increased risk of all-cause mortality in young adults born prematurely. While these preterm-birth-related conditions have been well characterized, less is known about the long-term effects of preterm birth on skeletal muscle health and, specifically, an individual's skeletal muscle hypertrophic potential later in life. In this review, we discuss how a confluence of potentially interrelated and self-perpetuating elements associated with preterm birth might converge on anabolic and catabolic pathways to ultimately blunt skeletal muscle hypertrophy, identifying critical areas for future research.

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.

Behavioural outcomes of children born with intrauterine growth restriction: protocol for a systematic review and meta-analysis

INTRODUCTION

Intrauterine growth restriction (IUGR) is a pregnancy condition, which is associated with poor perinatal outcomes and long-term neurodevelopmental impairment. Several studies also investigated the impact of IUGR on child behaviour (eg, internalising and externalising behaviour, social competencies). However, so far, no systematic review or meta-analysis has been conducted that summarises these effects while considering relevant third variables such as type of IUGR diagnosis and control group, or concurrent cognitive abilities. The objective of this study is to summarise the current evidence regarding the relationship between IUGR and behavioural outcomes from early childhood to young adulthood. Additionally, to explore how third variables such as type of control group, or cognitive abilities, relate to this association.

METHODS

Search strategy: The following electronic databases will be searched-Web of Science, Medline Ovid, PsycInfo, Cochrane Library, Scopus and Embase.

INCLUSION CRITERIA

observational (eg, cohort studies and case-control studies) and intervention studies (if standard care is used and norm values are reported for the control group) will be included if they quantitatively compare children with and without IUGR from the age of 2 to 18 years. The main outcomes are internalising and externalising behaviour, and social competencies.

ETHICS AND DISSEMINATION

No ethics approval was necessary for this protocol. Dissemination of findings will be done by publishing the results in peer-reviewed journals. The results of this systematic review will provide guidance for practice and counselling for clinicians and therapists facing patients affected by IUGR and their families.

PROSPERO REGISTRATION NUMBER

CRD42022347467.

Placental Pathology and Its Associations With Clinical Signs in Different Subtypes of Fetal Growth Restriction

OBJECTIVE

We evaluated placental alterations in different subtypes of fetal growth restriction (FGR) to determine any clinical associations.

METHODS

FGR placentas classified according to the Amsterdam criteria were correlated with clinical findings. Percentage of intact terminal villi and villous capillarization ratio were calculated in each specimen. Correlations of placental histopathology and perinatal outcomes were studied. 61 FGR cases were studied.

RESULTS

Early-onset-FGR was more often associated with preeclampsia and recurrence than late-onset-FGR; placentas from early-onset-FGR often had diffuse maternal (or fetal) vascular malperfusion and villitis of unknown etiology. Decreased percentage of intact terminal villi was associated with pathologic CTG. Decreased villous capillarization was associated with early-onset-FGR and birth weight below the second percentile. Avascular villi and infarction were more common when femoral length/abdominal circumference ratio was >0.26, and perinatal outcome was poor in this group.

CONCLUSION

In early-onset-FGR and preeclamptic FGR, altered vascularization of villi may have a key role in pathogenesis, and recurrent FGR is associated with villitis of unknown etiology. There is an association between femoral length/abdominal circumference ratio >0.26 and histopathological alterations of placenta in FGR pregnancies. There are no significant differences in the percentage of intact terminal villi between different FGR subtypes by onset or recurrency.

The effect of prenatal cannabis exposure on offspring preterm birth: a cumulative meta-analysis

BACKGROUND AND AIMS

Mixed results have been reported on the association between prenatal cannabis exposure and preterm birth. This study aimed to examine the magnitude and consistency of associations reported between prenatal cannabis exposure and preterm birth.

METHODS

This review was guided by the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. We performed a comprehensive search of the literature on the following electronic databases: PubMed, EMBASE, SCOPUS, Psych-INFO and Web of Science. The revised version of the Newcastle-Ottawa Scale (NOS) was used to appraise the methodological quality of the studies included in this review. Inverse variance weighted random-effects cumulative meta-analysis was undertaken to pool adjusted odds ratios (aOR) after sequential inclusion of each newly published study over time. The OR and 95% confidence interval (CI) limits required (stability threshold) for a new study to move the cumulative odds ratio to the null were also computed.

RESULTS

A total of 27 observational studies published between 1986 and 2022 were included in the final cumulative meta-analysis. The sample size of the studies ranged from 304 to 4.83 million births. Prenatal cannabis exposure was associated with an increased risk of preterm birth (pooled aOR = 1.35, 95% CI = 1.24-1.48). The stability threshold was 0.74 (95% CI limit = 0.81) by the end of 2022.

CONCLUSIONS

Offspring exposed to maternal prenatal cannabis use was associated with higher risk of preterm birth, which warrants public health messages to avoid such exposure, particularly during pregnancy.

Use of Head and Chest Circumference Ratio as an Index of Fetal Growth Retardation in Preterm Infants

We evaluated the relationship between fetal growth in preterm babies using the head circumference (HC)/chest circumference (CC) ratio and other anthropometric parameters at birth and at school age. Data were collected from 187 very low birth weight (VLBW) children born at less than 30 weeks of gestational age (GA) at birth and at 6 years. We assessed the correlation between the HC/CC ratio and body weight (BW), body length (BL), and HC z-scores at birth, and BW, body height (BH), and body mass index (BMI) z-scores at 6 years. Multiple regression analysis showed that BW z-score, BL z-score, and HC z-score at birth were significantly associated with HC/CC at birth. The BMI z-score at 6 years was also significantly associated with HC/CC at birth. The HC/CC ratio at birth is a reliable parameter for evaluating fetal growth restriction and a possible predictor of physical growth in VLBW children.

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.

Enhanced S100B expression in T and B lymphocytes in spontaneous preterm birth and preeclampsia

OBJECTIVES

S100B belongs to the family of danger signaling proteins. It is mainly expressed by glial-specific cells in the brain. However, S100B was also detected in other cell likewise immune cells. This molecule was suggested as biomarker for inflammation and fetal brain damage in spontaneous preterm birth (sPTB), preeclampsia (PE) and HELLP (hemolysis, elevated liver enzymes, and low platelet count).

METHODS

The aim of our study was to determine the concentration of S100B in maternal and cord blood (CB) plasma and placenta supernatant as well as the expression of S100B in maternal and CB CD4+ T cells and CD19+ B cells in sPTB and patients delivering following PE/HELLP diagnosis compared to women delivering at term (TD). The S100B expression was further related to the birth weight in our study cohort.

RESULTS

S100B concentration was enhanced in maternal and CB plasma of sPTB and PE/HELLP patients and positively correlated with interleukin-6 (IL-6) levels. Increased S100B was also confirmed in CB of small-for-gestational-age (SGA) infants. S100B expression in maternal blood was elevated in CD4+ T cells of PE/HELLP patients and patients who gave birth to SGA newborns as well as in CD19+ B cells of sPTB and PE/HELLP patients and patients with SGA babies. In CB, the expression of S100B was increased in CD19+ B cells of sPTB, PE/HELLP and SGA babies.

CONCLUSIONS

Our results support the hypothesis that S100B expression is enhanced in inflammatory events associated with preterm birth and that S100B expression in immune cells is a relevant marker for inflammation during pregnancy complications.

Translational insights into mechanisms and preventive strategies after renal injury in neonates

Adverse perinatal circumstances can cause acute kidney injury (AKI) and contribute to chronic kidney disease (CKD). Accumulating evidence indicate that a wide spectrum of perinatal conditions interferes with normal kidney development and ultimately leads to aberrant kidney structure and function later in life. The present review addresses the lack of mechanistic knowledge with regard to perinatal origins of CKD and provides a comprehensive overview of pre- and peri-natal insults, including genetic predisposition, suboptimal nutritional supply, obesity and maternal metabolic disorders as well as placental insufficiency leading to intrauterine growth restriction (IUGR), prematurity, infections, inflammatory processes, and the need for life-saving treatments (e.g. oxygen supplementation, mechanical ventilation, medications) in neonates. Finally, we discuss future preventive, therapeutic, and regenerative directions. In summary, this review highlights the perinatal vulnerability of the kidney and the early origins of increased susceptibility toward AKI and CKD during postnatal life. Promotion of kidney health and prevention of disease require the understanding of perinatal injury in order to optimize perinatal micro- and macro-environments and enable normal kidney development.

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.

OUP accepted manuscript

Fetal growth restriction (FGR) occurs when a fetus is unable to grow normally due to inadequate nutrient and oxygen supply from the placenta. Children born with FGR are at high risk of lifelong adverse neurodevelopmental outcomes, such as cerebral palsy, behavioral issues, and learning and attention difficulties. Unfortunately, there is no treatment to protect the FGR newborn from these adverse neurological outcomes. Chronic inflammation and vascular disruption are prevalent in the brains of FGR neonates and therefore targeted treatments may be key to neuroprotection. Tissue repair and regeneration via stem cell therapies have emerged as a potential clinical intervention for FGR babies at risk for neurological impairment and long-term disability. This review discusses the advancement of research into stem cell therapy for treating neurological diseases and how this may be extended for use in the FGR newborn. Leading preclinical studies using stem cell therapies in FGR animal models will be highlighted and the near-term steps that need to be taken for the development of future clinical trials.

Intrauterine growth restriction alters the activity of drug metabolising enzymes in the maternal-placental-fetal unit

PURPOSE

Ten percent of pregnancies are affected by intrauterine growth restriction (IUGR), and evidence suggests that affected neonates have reduced activity of hepatic cytochrome P450 (CYP) drug metabolising enzymes. Given that almost all pregnant individuals take medications and additional medications are often required during an IUGR pregnancy, we aimed to determine the impact of IUGR on hepatic CYP activity in sheep fetuses and pregnant ewes.

METHODS

Specific probes were used to determine the impact of IUGR on the activity of several CYP isoenzymes (CYP1A2, CYP2C19, CYP2D6 and CYP3A) in sheep fetuses and pregnant ewes. Probes were administered intravenously to the ewe at 132 days (d) gestation (term 150 d), followed by blood sampling from the maternal and fetal circulation over 24 h. Maternal and fetal liver tissue was collected at 139-140 d gestation, from which microsomes were isolated and incubated with probes. Metabolite and maternal plasma cortisol concentrations were measured using Liquid Chromatography - tandem mass spectrometry (LC-MS/MS).

RESULTS

Maternal plasma cortisol concentration and maternal hepatic CYP1A2 and CYP3A activity was significantly higher in IUGR pregnancies. Maternal hepatic CYP activity was higher than fetal hepatic CYP activity for all CYPs tested, and there was minimal CYP1A2 or CYP3A activity in the late gestation fetus when assessed using in vitro methods.

CONCLUSIONS

The physiological changes to the maternal-placental-fetal unit in an IUGR pregnancy have significant effects on maternal drug metabolism, suggesting changes in medications and/or doses may be required to optimise maternal and fetal health.

Birthweight and patterns of postnatal weight gain in very and extremely preterm babies in England and Wales, 2008-19: a cohort study

BACKGROUND

Intrauterine and postnatal weight are widely regarded as biomarkers of fetal and neonatal wellbeing, but optimal weight gain following preterm birth is unknown. We aimed to describe changes over time in birthweight and postnatal weight gain in very and extremely preterm babies, in relation to major morbidity and healthy survival.

METHODS

In this cohort study, we used whole-population data from the UK National Neonatal Research Database for infants below 32 weeks gestation admitted to neonatal units in England and Wales between Jan 1, 2008, and Dec 31, 2019. We used non-linear Gaussian process to estimate monthly trends, and Bayesian multilevel regression to estimate unadjusted and adjusted coefficients. We evaluated birthweight; weight change from birth to 14 days; weight at 36 weeks postmenstrual age; associated Z scores; and longitudinal weights for babies surviving to 36 weeks postmenstrual age with and without major morbidities. We adjusted birthweight for antenatal, perinatal, and demographic variables. We additionally adjusted change in weight at 14 days and weight at 36 weeks postmenstrual age, and their Z scores, for postnatal variables.

FINDINGS

The cohort comprised 90 817 infants. Over the 12-year period, mean differences adjusted for antenatal, perinatal, demographic, and postnatal variables were 0 g (95% compatibility interval -7 to 7) for birthweight (-0·01 [-0·05 to 0·03] for change in associated Z score); 39 g (26 to 51) for change in weight from birth to 14 days (0·14 [0·08 to 0·19] for change in associated Z score); and 105 g (81 to 128) for weight at 36 weeks postmenstrual age (0·27 [0·21 to 0·33] for change in associated Z score). Greater weight at 36 weeks postmenstrual age was robust to additional adjustment for enteral nutritional intake. In babies surviving without major morbidity, weight velocity in all gestational age groups stabilised at around 34 weeks postmenstrual age at 16-25 g per day along parallel percentile lines.

INTERPRETATION

The birthweight of very and extremely preterm babies has remained stable over 12 years. Early postnatal weight loss has decreased, and subsequent weight gain has increased, but weight at 36 weeks postmenstrual age is consistently below birth percentile. In babies without major morbidity, weight velocity follows a consistent trajectory, offering opportunity to construct novel preterm growth curves despite lack of knowledge of optimal postnatal weight gain.

FUNDING

UK Medical Research Council.

Swedish intrauterine growth reference ranges for estimated fetal weight

Fetal growth restriction is a strong risk factor for perinatal morbidity and mortality. Reliable standards are indispensable, both to assess fetal growth and to evaluate birthweight and early postnatal growth in infants born preterm. The aim of this study was to create updated Swedish reference ranges for estimated fetal weight (EFW) from gestational week 12-42. This prospective longitudinal multicentre study included 583 women without known conditions causing aberrant fetal growth. Each woman was assigned a randomly selected protocol of five ultrasound scans from gestational week 12 + 3 to 41 + 6. Hadlock's 3rd formula was used to estimate fetal weight. A two-level hierarchical regression model was employed to calculate the expected median and variance, expressed in standard deviations and percentiles, for EFW. EFW was higher for males than females. The reference ranges were compared with the presently used Swedish, and international reference ranges. Our reference ranges had higher EFW than the presently used Swedish reference ranges from gestational week 33, and higher median, 2.5th and 97.5th percentiles from gestational week 24 compared with INTERGROWTH-21st. The new reference ranges can be used both for assessment of intrauterine fetal weight and growth, and early postnatal growth in children born preterm.

Miscarriage matters: the epidemiological, physical, psychological, and economic costs of early pregnancy loss

Miscarriage is generally defined as the loss of a pregnancy before viability. An estimated 23 million miscarriages occur every year worldwide, translating to 44 pregnancy losses each minute. The pooled risk of miscarriage is 15·3% (95% CI 12·5-18·7%) of all recognised pregnancies. The population prevalence of women who have had one miscarriage is 10·8% (10·3-11·4%), two miscarriages is 1·9% (1·8-2·1%), and three or more miscarriages is 0·7% (0·5-0·8%). Risk factors for miscarriage include very young or older female age (younger than 20 years and older than 35 years), older male age (older than 40 years), very low or very high body-mass index, Black ethnicity, previous miscarriages, smoking, alcohol, stress, working night shifts, air pollution, and exposure to pesticides. The consequences of miscarriage are both physical, such as bleeding or infection, and psychological. Psychological consequences include increases in the risk of anxiety, depression, post-traumatic stress disorder, and suicide. Miscarriage, and especially recurrent miscarriage, is also a sentinel risk marker for obstetric complications, including preterm birth, fetal growth restriction, placental abruption, and stillbirth in future pregnancies, and a predictor of longer-term health problems, such as cardiovascular disease and venous thromboembolism. The costs of miscarriage affect individuals, health-care systems, and society. The short-term national economic cost of miscarriage is estimated to be £471 million per year in the UK. As recurrent miscarriage is a sentinel marker for various obstetric risks in future pregnancies, women should receive care in preconception and obstetric clinics specialising in patients at high risk. As psychological morbidity is common after pregnancy loss, effective screening instruments and treatment options for mental health consequences of miscarriage need to be available. We recommend that miscarriage data are gathered and reported to facilitate comparison of rates among countries, to accelerate research, and to improve patient care and policy development.

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).

Spontaneous Preterm Birth: Is Prevention with Aspirin Possible?

Background The rate of preterm births in Germany is 8.6%, which is very high compared to other European countries. As preterm birth contributes significantly to perinatal morbidity and mortality rates, the existing prevention strategies need to be optimized and expanded further. About ⅔ of all women with preterm birth have preterm labor or premature rupture of membranes. They are bracketed together under the term “spontaneous preterm birth” as opposed to iatrogenic preterm birth, for example as a consequence of preeclampsia or fetal growth retardation. Recent studies suggest that low-dose aspirin does not just reduce the rate of iatrogenic preterm births but can also further reduce the rate of spontaneous preterm births. This review article presents the current state of knowledge.

Method A selective literature search up until April 2020 was done in PubMed, using the terms “randomized trial”, “randomized study”, “spontaneous preterm birth”, and “aspirin”.

Results Secondary analyses of prospective randomized studies on the prevention of preeclampsia with low-dose aspirin show that this intervention also significantly reduced the rate of spontaneous preterm births in both high-risk and low-risk patient populations. The results of the ASPIRIN trial, a prospective, randomized, double-blinded multicenter study carried out in six developing countries, also point in this direction, with the figures showing that the daily administration of 81 mg aspirin starting before 14 weeks of gestation lowered the preterm birth rate of nulliparous women without prior medical conditions by around 11% (11.6 vs. 13.1%; RR 0.89; 95% CI: 0.81 – 0.98, p = 0.012).

Conclusion Further studies on this issue are urgently needed. If these confirm the currently available results, then it would be worth discussing whether general aspirin prophylaxis for all pregnant women starting at the latest in 12 weeks of gestation is indicated.

The Effects of Maternal Metformin Treatment on Late Prenatal and Early Postnatal Development of the Offspring Are Modulated by Sex

Metformin is currently used to improve pregnancy outcome in women affected by polycystic ovary syndrome (PCOS) or diabetes. However, metformin may also be useful in pregnancies at risk of intrauterine growth restriction (IUGR) since it improves placental efficiency and the fetuses' developmental competence. There is no data on the duration of the effect of this treatment from the prenatal up to the postnatal stages. Therefore, the present trial aimed at determining the impact of metformin treatment on the offspring neonatal traits and early postnatal development (i.e., during lactation) using an in vivo swine model. The results support that maternal metformin treatment during pregnancy induces protective changes in body shape and composition of the progeny (i.e., larger head size and body length at birth and higher total viscera weight at weaning). However, there were also major effects of the offspring sex (smaller corpulence in females and lower relative weight of main viscerae in males), which should be considered for further preclinical studies and when even the current clinical application in women affected by PCOS or diabetes is implemented.

Do patients with a short cervix, with or without an ultrasound-indicated cerclage, have an increased risk for a small for gestational age newborn?

INTRODUCTION

Mothers with a short cervix have been shown to have increased risk of spontaneous preterm delivery (PTD) and newborn morbidity. Those who require an ultrasound-indicated cerclage experience the highest rates of morbidity. Inflammation has been linked to a short cervix, and it has been linked to pregnancies affected by small for gestational age (SGA) newborns. To date, there are no studies that have investigated an association between a short cervix, with or without an ultrasound-indicated cerclage, and a SGA newborn.

METHODS

This was a case-control study examining all pregnancies with a transvaginal cervical length <25 mm found at their second trimester anatomy scan. Cases were subdivided into those who received an ultrasound-indicated cerclage (Group 1, n = 52) and those who did not (Group 2, n = 139). Controls were defined as pregnancies with a transvaginal cervical length >25 mm with no cerclage (Group 3, n = 186) whose due date was within 2 months of the case pregnancy. Each short cervix case was matched with a control from group 3 in a 1:1 ratio. The primary outcome was birthweight <10% (SGA). Unadjusted data was analyzed with simple odds ratios. A logistic regression was used to control for confounding variables and provide an adjusted odds ratios (aOR).

RESULTS

The incidence of SGA among cases overall (group 1 + group 2) was 13.6% (26/191). In group 3, the SGA incidence was 4.3% (8/186). The adjusted odds ratio (aOR) for a SGA infant was significant, 2.8 (95% CI 1.2, 6.6). Subgroup analysis showed that Group 1 had an increased risk for an SGA infant [aOR 4.9 (95% CI 1.8, 13.7)], but Group 2 did not show a significant finding [aOR 2.3 (95% CI 0.9, 5.7)].

CONCLUSION

Pregnancies complicated by a short cervical length <25mm, with or without a cerclage, were associated with an increased risk for a SGA newborn. Most of this significance was due to the pregnancies which received an ultrasound-indicated cerclage for a mid-trimester short cervix.

The impact of intrauterine growth restriction on cytochrome P450 enzyme expression and activity

With the increased prevalence of non-communicable disease and availability of medications to treat these and other conditions, a pregnancy free from prescribed medication exposure is rare. Up to 99% of women take at least one medication during pregnancy. These medications can be divided into those used to improve maternal health and wellbeing (e.g., analgesics, antidepressants, antidiabetics, antiasthmatics), and those used to promote the baby's wellbeing in either fetal (e.g., anti-arrhythmics) or postnatal life (e.g., antenatal glucocorticoids). These medications are needed for pre-existing or coincidental illnesses in the mother, maternal conditions induced by the pregnancy itself through to conditions that arise in the fetus or that will be encountered by the newborn. Thus, medications administered to the mother may be used to treat the mother, the fetus or both. Metabolism of medications is regulated by a range of physiological processes that change during pregnancy. Other pathological processes such as placental insufficiency can in turn have both immediate and lifelong adverse health consequences for babies. Individuals born growth restricted are more likely to require medications but may also have an altered ability to metabolise these medications in fetal and postnatal life. This review aims to determine the effect of suboptimal fetal growth on the fetal expression of the drug metabolising enzymes (DMEs) that convert medications into active or inactive metabolites, and the transporters that remove both these medications and their metabolites from the fetal compartment.

New Australian birthweight centiles

OBJECTIVES

To prepare more accurate population-based Australian birthweight centile charts by using the most recent population data available and by excluding pre-term deliveries by obstetric intervention of small for gestational age babies.

DESIGN

Population-based retrospective observational study.

SETTING

Australian Institute of Health and Welfare National Perinatal Data Collection.

PARTICIPANTS

All singleton births in Australia of 23-42 completed weeks' gestation and with spontaneous onset of labour, 2004-2013. Births initiated by obstetric intervention were excluded to minimise the influence of decisions to deliver small for gestational age babies before term.

MAIN OUTCOME MEASURES

Birthweight centile curves, by gestational age and sex.

RESULTS

Gestational age, birthweight, sex, and labour onset data were available for 2 807 051 singleton live births; onset of labour was spontaneous for 1 582 137 births (56.4%). At pre-term gestational ages, the 10th centile was higher than the corresponding centile in previous Australian birthweight charts based upon all births.

CONCLUSION

Current birthweight centile charts probably underestimate the incidence of intra-uterine growth restriction because obstetric interventions for delivering pre-term small for gestational age babies depress the curves at earlier gestational ages. Our curves circumvent this problem by excluding intervention-initiated births; they also incorporate more recent population data. These updated centile curves could facilitate more accurate diagnosis of small for gestational age babies in Australia.

Comparison of placental elasticity in normal and intrauterine growth retardation pregnancies by ex vivo strain elastography

OBJECTIVE

To compare the placental elasticity in fetuses with or without intrauterine growth restriction (IUGR).

MATERIALS AND METHODS

One hundred pregnant women (50 IUGR and 50 healthy) with anteriorly located placenta were evaluated during the third trimester of pregnancy. Measurements were carried out by a machine that has a real-time elastographic ultrasonography feature. After obtaining the optimum image, three areas (subcutaneous tissue, center, and the edge of the placenta) were provided to identify the placental strain values. Then, the placental strain ratio (PSR) value was calculated automatically. Two groups compared in terms of their PSR values.

RESULTS

There was a significant difference in placental elasticity between the groups (P < 0.001). PSR value was 2.8 ± 1.2 in the IUGR group and 1.3 ± 0.6 in the control group. A PSR value of 1.78 had an 86% sensitivity (OR 4.3) and 80% specificity (OR 0.17) in IUGR cases. The positive predictive value was 81.1% and the negative predictive value was 85.1% for this cut-off value.

CONCLUSIONS

We have shown that placental strain ratio is increased during the third trimester of pregnancy in fetuses with IUGR. Increased stiffness and elasticity may be responsible for the onset of IUGR in some cases.

A bibliometric analysis of Intrauterine Growth Restriction research

Intrauterine growth restriction (IUGR) is not a new subject in pregnancy. Nevertheless, this concept has newly begun to be integrated into pregnancy studies. We recognized articles that were published in English from 1977 to 2019 through electronic searches of the Web of Science™ database. The WoS database was searched for all published articles that compared preeclampsia from 1977 to January 2020. About 1469 documents in obstetrics and gynecology areas were analyzed in WoS database. VOSviewer software was employed to visualize the networks. The survey resulted in a 1469 published documents from 1977 to 2020. 'Gratacos' from Spain and 'Cetin' from Italy contributed the most publications. The greatest contribution came from the 'USA' (n = 498), 'Italy' (n = 155), and 'England' (n = 147). Furthermore, our results found that among these journals, the 'AJOG' (n = 318) and the 'Reproductive Sciences' (n = 209) published the largest number of papers. The top 100 most cited papers showed that 30% were reported in the 'AJOG'. About half the articles were published in the last decade and the most common studies were research paper (77%). The co-occurrence and co-citation analysis showed that the study formed four clusters. Finally, the strategic map was designed. We found that there existed an increasing trend in the large amount of publication on IUGR from 1977 to 2020. The number of studies in IUGR has substantially improved in the last decade. Authors from the 'USA' appeared the most proactive in addressing the IUGR area. By studying these articles, we propose important to support not only for grinding the IUGR challenges field but also for designing a new trend in this area.

Identification of the optimal growth charts for use in a preterm population: An Australian state-wide retrospective cohort study

BACKGROUND

Preterm infants are a group at high risk of having experienced placental insufficiency. It is unclear which growth charts perform best in identifying infants at increased risk of stillbirth and other adverse perinatal outcomes. We compared 2 birthweight charts (population centiles and INTERGROWTH-21st birthweight centiles) and 3 fetal growth charts (INTERGROWTH-21st fetal growth charts, World Health Organization fetal growth charts, and Gestation Related Optimal Weight [GROW] customised growth charts) to identify which chart performed best in identifying infants at increased risk of adverse perinatal outcome in a preterm population.

METHODS AND FINDINGS

We conducted a retrospective cohort study of all preterm infants born at 24.0 to 36.9 weeks gestation in Victoria, Australia, from 2005 to 2015 (28,968 records available for analysis). All above growth charts were applied to the population. Proportions classified as <5th centile and <10th centile by each chart were compared, as were proportions of stillborn infants considered small for gestational age (SGA, <10th centile) by each chart. We then compared the relative performance of non-overlapping SGA cohorts by each chart to our low-risk reference population (infants born appropriate size for gestational age [>10th and <90th centile] by all intrauterine charts [AGAall]) for the following perinatal outcomes: stillbirth, perinatal mortality (stillbirth or neonatal death), Apgar <4 or <7 at 5 minutes, neonatal intensive care unit admissions, suspicion of poor fetal growth leading to expedited delivery, and cesarean section. All intrauterine charts classified a greater proportion of infants as <5th or <10th centile than birthweight charts. The magnitude of the difference between birthweight and fetal charts was greater at more preterm gestations. Of the fetal charts, GROW customised charts classified the greatest number of infants as SGA (22.3%) and the greatest number of stillborn infants as SGA (57%). INTERGROWTH classified almost no additional infants as SGA that were not already considered SGA on GROW or WHO charts; however, those infants classified as SGA by INTERGROWTH had the greatest risk of both stillbirth and total perinatal mortality. GROW customised charts classified a larger proportion of infants as SGA, and these infants were still at increased risk of mortality and adverse perinatal outcomes compared to the AGAall population. Consistent with similar studies in this field, our study was limited in comparing growth charts by the degree of overlap, with many infants classified as SGA by multiple charts. We attempted to overcome this by examining and comparing sub-populations classified as SGA by only 1 growth chart.

CONCLUSIONS

In this study, fetal charts classified greater proportions of preterm and stillborn infants as SGA, which more accurately reflected true fetal growth restriction. Of the intrauterine charts, INTERGROWTH classified the smallest number of preterm infants as SGA, although it identified a particularly high-risk cohort, and GROW customised charts classified the greatest number at increased risk of perinatal mortality.

Large-for-gestational-age fetuses have an increased risk for spontaneous preterm birth

OBJECTIVE

Our aim was to investigate the association between large-for-gestational-age and the risk of spontaneous preterm birth.

STUDY DESIGN

We studied nulliparous women with a singleton gestation using data from the Dutch perinatal registry from 1999 to 2010. Neonates were categorized according to the Hadlock fetal weight standard, into 10th to 90th percentile, 90th to 97th percentile, or above 97th percentile. Outcomes were preterm birth <37⁺⁰ weeks and preterm birth between 25⁺⁰-27⁺⁶ weeks, 28⁺⁰-30⁺⁶ weeks, 31⁺⁰-33⁺⁶ weeks, and 34⁺⁰-36⁺⁶ weeks.

RESULTS

We included 547,418 women. The number of spontaneous preterm births <37 weeks was significantly increased in the large-for-gestational-age group ( > p97) compared with fetuses with a normal growth (p10-p90) (11.3% vs. 7.3%, odds ratio (OR) 1.8; 95% CI 1.7-1.9). The same results were found when limiting analyses to women with certain pregnancy duration (after in vitro fertilization).

CONCLUSION

Large-for-gestational-age increases the risk of spontaneous preterm delivery from 25 weeks of gestation onwards.

Systematic review and meta-analysis of adverse pregnancy outcomes after uterine adenomyosis

BACKGROUND

Studies on the impact of adenomyosis and its pregnancy complications have yielded conflicting results.

OBJECTIVE

To determine the likelihood of adverse pregnancy outcomes among women with adenomyosis relative to women without adenomyosis.

SEARCH STRATEGY

PubMed, Embase, Scopus, and Web of Science were searched for studies published up to June 15, 2018.

SELECTION CRITERIA

Observational studies with medically confirmed pregnancy outcomes as endpoints.

DATA COLLECTION AND ANALYSIS

Two researchers independently screened and selected relevant studies. Dichotomous data for all adverse pregnancy outcomes were expressed as an odds ratio (OR) with 95% confidence interval (CI), and combined in a meta-analysis by using a random-effects model.

MAIN RESULTS

Six studies (322 cases and 9420 controls) were eligible for inclusion in the meta-analysis. Women with adenomyosis had an increased likelihood of preterm birth (OR, 3.05; 95% CI, 2.08-4.47; P˂0.001), small for gestational age (OR, 3.22; 95% CI, 1.71-6.08; P˂0.001), and pre-eclampsia (OR, 4.35; 95% CI, 1.07-17.72; P=0.042).

CONCLUSION

Adenomyosis seems to have a detrimental impact on pregnancy outcomes, resulting in a higher likelihood of preterm birth, small for gestational age, and pre-eclampsia.

Spontaneous premature birth as a target of genomic research

Spontaneous preterm birth is a serious and common pregnancy complication associated with hormonal dysregulation, infection, inflammation, immunity, rupture of fetal membranes, stress, bleeding, and uterine distention. Heredity is 25-40% and mostly involves the maternal genome, with contribution of the fetal genome. Significant discoveries of candidate genes by genome-wide studies and confirmation in independent replicate populations serve as signposts for further research. The main task is to define the candidate genes, their roles, localization, regulation, and the associated pathways that influence the onset of human labor. Genomic research has identified some candidate genes that involve growth, differentiation, endocrine function, immunity, and other defense functions. For example, selenocysteine-specific elongation factor (EEFSEC) influences synthesis of selenoproteins. WNT4 regulates decidualization, while a heat-shock protein family A (HSP70) member 1 like, HSPAIL, influences expression of glucocorticoid receptor and WNT4. Programming of pregnancy duration starts before pregnancy and during placentation. Future goals are to understand the interactive regulation of the pathways in order to define the clocks that influence the risk of prematurity and the duration of pregnancy. Premature birth has a great impact on the duration and the quality of life. Intensification of focused research on causes, prediction and prevention of prematurity is justified.

Neurodevelopmental outcomes at five years after early-onset fetal growth restriction: Analyses in a Dutch subgroup participating in a European management trial

OBJECTIVE

The objective of this study is to explore developmental outcomes at five years after early-onset fetal growth restriction (FGR).

STUDY DESIGN

Retrospective data analysis of prospective follow-up of patients of three Dutch centres, who participated in a twenty centre European randomized controlled trial on timing of delivery in early-onset FGR. Developmental outcome of very preterm infants born after extreme FGR is assessed at (corrected) age of five.

RESULTS

Seventy-four very preterm FGR children underwent follow-up at the age of five. Mean gestational age at birth was 30 weeks and birth weight was 910 g, 7% had a Bayley score <85 at two years. Median five years' FSIQ was 97, 16% had a FSIQ < 85, and 35% had one or more IQ scores <85. Motor score ≤ 7 on movement ABC-II (M-ABC-II-NL) was seen in 38%. Absent or reversed end-diastolic flow, gestational age at delivery, birthweight and neonatal morbidity were related to an FSIQ < 85. Any abnormal IQ scale score was related to birthweight, male sex and severity of FGR, and abnormal motor score to male sex and bronchopulmonary dysplasia (BPD).

CONCLUSIONS

Overall, median cognitive outcome at five years was within normal range, but 35% of the children had any abnormal IQ score at age five, depending on the IQ measure, and motor impairment was seen in 38% of the children. GA at delivery, birthweight, EDF prior to delivery and neonatal morbidity were the most important risk factors for cognitive outcomes.

Neonatal Morbidities of Fetal Growth Restriction: Pathophysiology and Impact

Being born small lays the foundation for short-term and long-term implications for life. Intrauterine or fetal growth restriction describes the pregnancy complication of pathological reduced fetal growth, leading to significant perinatal mortality and morbidity, and subsequent long-term deficits. Placental insufficiency is the principal cause of FGR, which in turn underlies a chronic undersupply of oxygen and nutrients to the fetus. The neonatal morbidities associated with FGR depend on the timing of onset of placental dysfunction and growth restriction, its severity, and the gestation at birth of the infant. In this review, we explore the pathophysiological mechanisms involved in the development of major neonatal morbidities in FGR, and their impact on the health of the infant. Fetal cardiovascular adaptation and altered organ development during gestation are principal contributors to postnatal consequences of FGR. Clinical presentation, diagnostic tools and management strategies of neonatal morbidities are presented. We also present information on the current status of targeted therapies. A better understanding of neonatal morbidities associated with FGR will enable early neonatal detection, monitoring and management of potential adverse outcomes in the newborn period and beyond.

Hormonal Changes Associated With Intra-Uterine Growth Restriction: Impact on the Developing Brain and Future Neurodevelopment

The environment in which a fetus develops is not only important for its growth and maturation but also for its long-term postnatal health and neurodevelopment. Several hormones including glucocorticosteroids, estrogens and progesterone, insulin growth factor and thyroid hormones, carefully regulate the growth of the fetus and its metabolism during pregnancy by controlling the supply of nutrients crossing the placenta. In addition to fetal synthesis, hormones regulating fetal growth are also expressed and regulated in the placenta, and they play a key role in the vulnerability of the developing brain and its maturation. This review summarizes the current understanding and evidence regarding the involvement of hormonal dysregulation associated with intra-uterine growth restriction and its consequences on brain development.

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.

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.

Three-dimensional ultrasound first trimester fetal volume measurement and its relation to pregnancy outcome

AIM OF WORK

To determine whether fetal volume (FV) measured by three-dimensional (3D) ultrasound was able to detect fetuses at risk of low birth weight (primary outcome) and/or preterm labor (secondary outcome).

METHODS

One hundred pregnant women carrying a singleton living pregnancy who were sure of dates, and had a dating scan, with gestational age between 11 weeks and 13 weeks+6 days coming for routine first trimester nuchal translucency (NT) were examined by both two-dimensional (2D) and 3D ultrasound (Vocal System) for crown-rump length (CRL) and FV then followed up regularly every 4 weeks until 28 weeks then biweekly until 36 weeks then weekly until delivery both clinically and by ultrasound biometry.

FINDINGS

Eighty-seven cases had a normal outcome, while the remaining 13 cases had either preterm labor (four cases) or low-birth weight (nine cases). FV positively correlated with CRL (P=0.026), gestational age in weeks (P=0.002), neonatal body weight in grams (P=0.018) and neonatal body length at birth (P=0.04). A mean FV of 8.3 mm3 was association with neonatal complications (P=0.045). A cut-off point of 9 mm3 for FV was associated with 100% sensitivity for detection of the date of birth, while a cut-off point of 9.15 mm3 for FV was associated 100% sensitivity for detection of neonatal birth weight.

CONCLUSION

3D assessment of FV in the first trimester provides an accurate method for predicting pregnancy outcome namely low birth weight and neonatal complications, however, it is a better positive predictor than a negative one.

Risk of stillbirth, preterm delivery, and fetal growth restriction following exposure in a previous birth: systematic review and meta-analysis

BACKGROUND

Little is known about the risk of non-recurrent adverse birth outcomes.

OBJECTIVES

To evaluate the risk of stillbirth, preterm birth (PTB), and small for gestational age (SGA) as a proxy for fetal growth restriction (FGR) following exposure to one or more of these factors in a previous birth.

SEARCH STRATEGY

We searched MEDLINE, EMBASE, Maternity and Infant Care, and Global Health from inception to 30 November 2016.

SELECTION CRITERIA

Studies were included if they investigated the association between stillbirth, PTB, or SGA (as a proxy for FGR) in two subsequent births.

DATA COLLECTION AND ANALYSIS

Meta-analysis and pooled association presented as odds ratios (ORs) and adjusted odds ratios (aORs).

MAIN RESULTS

Of the 3399 studies identified, 17 met the inclusion criteria. A PTB or SGA (as a proxy for FGR) infant increased the risk of subsequent stillbirth ((pooled OR 1.70; 95% confidence interval, 95% CI, 1.34-2.16) and (pooled OR 1.98; 95% CI 1.70-2.31), respectively). A combination of exposures, such as a preterm SGA (as a proxy for FGR) birth, doubled the risk of subsequent stillbirth (pooled OR 4.47; 95% CI 2.58-7.76). The risk of stillbirth also varied with prematurity, increasing three-fold following PTB <34 weeks of gestation (pooled OR 2.98; 95% CI 2.05-4.34) and six-fold following preterm SGA (as a proxy for FGR) <34 weeks of gestation (pooled OR 6.00; 95% CI 3.43-10.49). A previous stillbirth increased the risk of PTB (pooled OR 2.82; 95% CI 2.31-3.45), and subsequent SGA (as a proxy for FGR) (pooled OR 1.39; 95% CI 1.10-1.76).

CONCLUSION

The risk of stillbirth, PTB, or SGA (as a proxy for FGR) was moderately elevated in women who previously experienced a single exposure, but increased between two- and three-fold when two prior adverse outcomes were combined. Clinical guidelines should consider the inter-relationship of stillbirth, PTB, and SGA, and that each condition is an independent risk factor for the other conditions.

TWEETABLE ABSTRACT

Risk of adverse birth outcomes in next pregnancy increases with the combined number of previous adverse events.

PLAIN LANGUAGE SUMMARY

Why and how was the study carried out? Each year, around 2.6 million babies are stillborn, 15 million are born preterm (<37 weeks of gestation), and 32 million are born small for gestational age (less than tenth percentile for weight, smaller than usually expected for the relevant pregnancy stage). Being born preterm or small for gestational age can increase the chance of long-term health problems. The effect of having a stillbirth, preterm birth, or small-for-gestational-age infant in a previous pregnancy on future pregnancy health has not been summarised. We identified 3399 studies of outcomes of previous pregnancies, and 17 were summarised by our study. What were the main findings? The outcome of the previous pregnancy influenced the risk of poor outcomes in the next pregnancy. Babies born to mothers who had a previous preterm birth or small-for-gestational-age birth were more likely to be stillborn. The smaller and the more preterm the previous baby, the higher the risk of stillbirth in the following pregnancy. The risk of stillbirth in the following pregnancy was doubled if the previous baby was born both preterm and small for gestational age. Babies born to mothers who had a previous stillbirth were more likely to be preterm or small for gestational age. What are the limitations of the work? We included a small number of studies, as there are not enough studies in this area (adverse birth outcomes followed by adverse cross outcomes in the next pregnancy). We found very few studies that compared the risk of small for gestational age after preterm birth or stillbirth. Definitions of stillbirth, preterm birth categories, and small for gestational age differed across studies. We did not know the cause of stillbirth for most studies. What are the implications for patients? Women who have a history of poor pregnancy outcomes are at greater risk of poor outcomes in following pregnancies. Health providers should be aware of this risk when treating patients with a history of poor pregnancy outcomes.

Variation in term birthweight across European countries affects the prevalence of small for gestational age among very preterm infants

AIM

This study assessed the prevalence of small for gestational age (SGA) among very preterm (VPT) infants using national and European intrauterine references.

METHODS

We generated country-specific and common European intrauterine growth references for 11 European countries, according to Gardosi's approach and Hadlock's foetal growth model, using national data on birthweights by sex. These references were applied to the Effective Perinatal Intensive Care in Europe (EPICE) cohort, which comprised 7766 live VPT births without severe congenital anomalies under 32 weeks of gestation in 2011-2012, to estimate the prevalence of infants with SGA birthweights, namely those below the 10th percentile.

RESULTS

The SGA prevalence was 31.8% with country-specific references and 34.0% with common European references. The European references yielded a 10-point difference in the SGA prevalence between countries with lower term birthweights (39.9%) - Portugal, Italy and France - and higher term birthweights, namely Denmark, the Netherlands, Sweden (28.9%; p < 0.001). This was not observed with country-specific references, where the respective figures were 32.4% and 33.9% (p = 0.34), respectively.

CONCLUSION

One-third of VPT infants were SGA according to intrauterine references. Common European references showed significant differences in SGA prevalence between countries with high and low-term birthweights.

A simple clinical method to identify women at higher risk of preeclampsia

An outstanding issue is how to efficiently identify women at high risk of preeclampsia. This retrospective cohort study included 8672 pregnancies at a single centre in Toronto. We tested our simple method - presence vs. absence of≥1 major (pre-pregnancy BMI>30kg/m², chronic hypertension, pre-pregnancy diabetes mellitus and assisted reproductive therapy) or≥2 minor (prior stillbirth, age>40years, nulliparity, multifetal pregnancy, chronic kidney disease, and SLE) risk factors for PE. The RR of PE was 8.4 (95% CI 5.3-13.2) and the model C-statistic 0.74 (95% CI 0.69-0.79). Further testing of this method elsewhere is warranted.

Preterm Delivery as a Unique Pathophysiologic State Characterized by Maternal Soluble FMS-Like Tyrosine Kinase 1 and Uterine Artery Resistance During Pregnancy: A Longitudinal Cohort Study

BACKGROUND

Preterm delivery (PTD) may be characterized by altered interrelationships among angiogenic factors and measures of placental function. We analyzed the longitudinal relationship between maternal serum concentrations of soluble fms-like tyrosine kinase 1 (sFlt1), an important antiangiogenic factor, and uterine artery resistance in pregnancies resulting in preterm and term deliveries.

METHODS

Data were collected in a longitudinal cohort study involving 278 women monitored at 6 to 10, 10 to 14, 16 to 20, 22 to 26, and 32 to 36 weeks of gestation. Concentrations of maternal serum sFlt1 were determined using solid-phase enzyme-linked immunosorbent assay, and uterine artery resistance indices (RI) were measured by Doppler velocimetry at each interval. Preterm delivery was defined as birth before 37-weeks completed gestation. Data analyses used multivariable repeated measures regression models.

RESULTS

Uterine artery RI decreased across gestation. As pregnancy progressed, RI trajectories diverged for term and preterm deliveries; the mean RI was significantly higher in third trimester for pregnancies resulting in PTD ( P = .08). sFlt1 was stable through 21 3/7 weeks of gestation and then increased rapidly; women who delivered preterm had significantly higher sFlt1 levels in the third trimester ( P = .04). The relationship between uterine artery RI and sFlt1 from the prior visit was significantly different between the groups ( P < .0001). For term deliveries, higher sFlt1 concentrations were associated with a smaller RI at the subsequent visit (β = -.08, 95% confidence interval [CI]: -0.14 to -0.02). For PTD, higher sFlt1 concentrations were associated with a larger uterine artery RI (β = .14, 95% CI: 0.06 to 0.22).

CONCLUSION

PTD is characterized by altered relationships between angiogenic factors and placental vascular blood flow starting in early pregnancy.