Risk factors for late preterm and term stillbirth: A secondary analysis of an individual participant data meta-analysis

OBJECTIVE

Identify independent and novel risk factors for late-preterm (28-36 weeks) and term (≥37 weeks) stillbirth and explore development of a risk-prediction model.

DESIGN

Secondary analysis of an Individual Participant Data (IPD) meta-analysis investigating modifiable stillbirth risk factors.

SETTING

An IPD database from five case-control studies in New Zealand, Australia, the UK and an international online study.

POPULATION

Women with late-stillbirth (cases, n = 851), and ongoing singleton pregnancies from 28 weeks' gestation (controls, n = 2257).

METHODS

Established and novel risk factors for late-preterm and term stillbirth underwent univariable and multivariable logistic regression modelling with multiple sensitivity analyses. Variables included maternal age, body mass index (BMI), parity, mental health, cigarette smoking, second-hand smoking, antenatal-care utilisation, and detailed fetal movement and sleep variables.

MAIN OUTCOME MEASURES

Independent risk factors with adjusted odds ratios (aOR) for late-preterm and term stillbirth.

RESULTS

After model building, 575 late-stillbirth cases and 1541 controls from three contributing case-control studies were included. Risk factor estimates from separate multivariable models of late-preterm and term stillbirth were compared. As these were similar, the final model combined all late-stillbirths. The single multivariable model confirmed established demographic risk factors, but additionally showed that fetal movement changes had both increased (decreased frequency) and reduced (hiccoughs, increasing strength, frequency or vigorous fetal movements) aOR of stillbirth. Poor antenatal-care utilisation increased risk while more-than-adequate care was protective. The area-under-the-curve was 0.84 (95% CI 0.82-0.86).

CONCLUSIONS

Similarities in risk factors for late-preterm and term stillbirth suggest the same approach for risk-assessment can be applied. Detailed fetal movement assessment and inclusion of antenatal-care utilisation could be valuable in late-stillbirth risk assessment.

Second-trimester maternal distress increases the risk of small for gestational age

BACKGROUND

The effect of prenatal distress on the risk of a small for gestational age (SGA) infant is uncertain. We have addressed the influences of prenatal stress, anxiety and depression on the risk of SGA. We also examined the effects of infant sex and timing of distress during pregnancy on any observed associations.

METHOD

The study population comprised 5606 healthy nulliparous pregnant women who participated in the international prospective Screening for Obstetric and Pregnancy Endpoints (SCOPE) study. Women completed the Perceived Stress Scale (PSS), the short form of the Spielberger State-Trait Anxiety Inventory (STAI) and the Edinburgh Postnatal Depression Scale (EPDS) at 15 ± 1 and 20 ± 1 weeks' gestation. SGA was defined as birthweight below the 10th customized percentile. Logistic regression was used for data analysis, adjusting for several potential confounders such as maternal age, body mass index (BMI), smoking, socio-economic status and physical exercise.

RESULTS

The risk of SGA was increased in relation to mild [adjusted odds ratio (aOR) 1.35, 95% confidence interval (CI) 1.07-1.71], moderate (aOR 1.26, 95% CI 1.06-1.49), high (aOR 1.45, 95% CI 1.08-1.95) and very high stress scores (aOR 1.56, 95% CI 1.03-2.37); very high anxiety score (aOR 1.45, 95% CI 1.13-1.86); and very high depression score (aOR 1.14, 95% CI 1.05-1.24) at 20 ± 1 weeks' gestation. Sensitivity analyses showed that very high anxiety and very high depression increases the risk of SGA in males but not in females whereas stress increases the risk of SGA in both males and females.

CONCLUSIONS

These findings suggest that prenatal stress, anxiety and depression measured at 20 weeks' gestation increase the risk of SGA. The effects of maternal anxiety and depression on SGA were strongest in male infants.

Angiogenic factors combined with clinical risk factors to predict preterm pre-eclampsia in nulliparous women: a predictive test accuracy study

OBJECTIVES

To assess the performance of clinical risk factors, uterine artery Doppler and angiogenic markers to predict preterm pre-eclampsia in nulliparous women.

DESIGN

Predictive test accuracy study.

SETTING

Prospective multicentre cohort study Screening for Pregnancy Endpoints (SCOPE).

METHODS

Low-risk nulliparous women with a singleton pregnancy were recruited. Clinical risk factor data were obtained and plasma placental growth factor (PlGF), soluble endoglin and soluble fms-like tyrosine kinase-1 (sFlt-1) were measured at 14-16 weeks of gestation. Prediction models were developed using multivariable stepwise logistic regression.

MAIN OUTCOME MEASURE

Preterm pre-eclampsia (delivered before 37(+0)  weeks of gestation).

RESULTS

Of the 3529 women recruited, 187 (5.3%) developed pre-eclampsia of whom 47 (1.3%) delivered preterm. Controls (n = 188) were randomly selected from women without preterm pre-eclampsia and included women who developed other pregnancy complications. An area under a receiver operating characteristic curve (AUC) of 0.76 (95% CI 0.67-0.84) was observed using previously reported clinical risk variables. The AUC improved following the addition of PlGF measured at 14-16 weeks (0.84; 95% CI 0.77-0.91), but no further improvement was observed with the addition of uterine artery Doppler or the other angiogenic markers. A sensitivity of 45% (95% CI 0.31-0.59) (5% false-positive rate) and post-test probability of 11% (95% CI 9-13) were observed using clinical risk variables and PlGF measurement.

CONCLUSIONS

Addition of plasma PlGF at 14-16 weeks of gestation to clinical risk assessment improved the identification of nulliparous women at increased risk of developing preterm pre-eclampsia, but the performance is not sufficient to warrant introduction as a clinical screening test. These findings are marker dependent, not assay dependent; additional markers are needed to achieve clinical utility.

The impact of maternal body mass index on the phenotype of pre-eclampsia: a prospective cohort study

OBJECTIVE

We hypothesised that among nulliparous women with pre-eclampsia, overweight or obese women would have a different phenotype of pre-eclampsia compared with normal weight women with pre-eclampsia. Specifically, they are more likely to develop term pre-eclampsia and less likely to have indicators of impaired placental perfusion, e.g. abnormal uterine artery Doppler or a small-for-gestational-age (SGA) infant.

DESIGN

Prospective, multicentre, cohort SCOPE study (n = 3170).

SETTING

New Zealand and Australia.

POPULATION

Nulliparous women who developed pre-eclampsia.

METHODS

Participants were interviewed at 14-16 weeks of gestation, uterine artery Doppler studies were performed at 19-21 weeks and pregnancy outcome was tracked prospectively.

MAIN OUTCOME MEASURES

Rates of abnormal uterine artery Doppler indices, term/preterm birth and SGA infants were compared between normal, overweight and obese women with pre-eclampsia. Multivariable analysis was performed to examine the association between body mass index (BMI) and term pre-eclampsia.

RESULTS

Of 178 women with pre-eclampsia, one underweight woman was excluded and 66 (37%) were normal weight, 52 (29%) were overweight and 59 (34%) were obese. Pre-eclampsia developed preterm in 26% of women and at term in 74% of women. There were no differences in the rates of term/preterm pre-eclampsia, abnormal uterine artery Doppler indices or SGA infants between BMI groups (P > 0.10). No independent association between BMI and term pre-eclampsia was found (P = 0.56).

CONCLUSIONS

Among women with pre-eclampsia, those who are overweight or obese in early pregnancy are not more likely to have term pre-eclampsia compared with women with a normal BMI. Overweight and obese women require vigilant surveillance for the development of preterm as well as term pre-eclampsia.

A functional variant in the thrombospondin-1 gene and the risk of small for gestational age infants

INTRODUCTION

Thrombospondin-1 (TSP-1) is a prothrombotic and anti-angiogenic glycoprotein expressed in the placenta. A functional single nucleotide polymorphism in the TSP-1 gene (TSP-1 A2210G) is a risk factor for familial premature myocardial infarction. Small for gestational age (SGA) infants are at increased risk of coronary artery disease in adult life and common genetic factors may underlie both conditions. We investigated the association of TSP-1 A2210G in SGA infants and their parents.

METHOD

The 3234 nulliparous pregnant women, their partners and babies were recruited in Adelaide and Auckland to a prospective multicenter cohort study. Amongst 2123 Caucasian women, 216 (10.2%) delivered an SGA infant, defined as birth weight < 10th customized centile adjusted for maternal height, weight, parity and ethnicity, as well as gestational age at delivery and infant sex. Uncomplicated pregnancies served as controls (n = 1185). DNA extracted from peripheral/cord blood or buccal swabs was genotyped using Sequenom MassARRAY. Multivariable logistic regression was used to compare the odds of SGA between the genotype groups adjusting for potential confounders.

RESULTS

Paternal (adjOR, 1.4; 95% CI 1.0-2.0) and neonatal (adjOR, 1.8; 95% CI, 1.1-2.7) TSP-1 A2210G associates with SGA. The maternal polymorphism approaches significance for an association with SGA (adjOR, 1.3; 95% CI, 0.9-1.9). Maternal TSP-1 A2210G associates with a reduced maternal birth weight adjusted for gestational age at delivery (P = 0.03).

CONCLUSION

The TSP-1 A2210G polymorphism, which is a risk factor for myocardial infarction, is associated with SGA pregnancies, suggesting that this polymorphism may associate with the risk of vascular disorders across the life course.

The association between customised small for gestational age infants and pre-eclampsia or gestational hypertension varies with gestation at delivery

OBJECTIVES

(1) To describe the association between small for gestational age (SGA) infants and pre-eclampsia (PE) and gestational hypertension (GH) and (2) to determine how this association changes with gestational age at delivery using customised centiles to classify infants as SGA.

DESIGN

A retrospective observational study.

SETTING

National Women's Hospital, a Tertiary Referral Centre in Auckland, New Zealand.

POPULATION

A total of 17 855 nulliparous women delivering between 1992 and 1999.

METHODS

A comparison of the number of women with a customised SGA infant, PE and GH according to gestational age at delivery.

MAIN OUTCOME MEASURES

The incidence of SGA infants (defined as birthweight <10th customised centile), PE and GH at <34, 34-36(+6) and > or =37 weeks.

RESULTS

A total of 1847 (10.3%) infants were SGA, 520 (2.9%) women had PE and 1361 (7.6%) had GH. SGA, PE and GH all occurred more commonly with increasing gestation at delivery with 85%, 62% and 90% of cases delivered at term. In women delivering SGA infants, coexisting PE was more likely to occur among those delivered preterm than at term (38.6% at <34 weeks [relative risk, RR 10.2 95%CI 7.3-14.4], 22.4% at 34-36(+6) weeks [RR 6.0 95%CI 4.1-8.6] and 3.8% at > or =37 weeks [OR 1.0]). Women with preterm PE were more likely to have a SGA infant than women with term PE (57.1% at <34 weeks [RR 3.1 95%CI 2.3-4.2], 31.7% at 34-36(+6) weeks [RR 1.7 95%CI 1.2-2.5]) and 18.3% at > or =37 weeks [OR 1.0]). There was a similar association between GH and SGA infants as gestation advanced (57.6% at <34 weeks [RR 4.8 95%CI 3.4-6.6], 30.5% at 34-36(+6) weeks [RR 2.5 95%CI 1.8-3.5] and 12.1% > or =37 weeks [OR 1.0]).

CONCLUSIONS

SGA infants and PE are more likely to coexist in preterm births compared with term births. This is likely to reflect the degree of placental involvement in each disease process.

Activated endothelial cells resist displacement by trophoblast in vitro

BACKGROUND

Transformation of the spiral arteries by invading trophoblasts is an essential prerequisite to the development of a healthy fully grown fetus. Reduced transformation of the spiral arteries is a characteristic feature of pregnancies complicated by several diseases of pregnancy including preeclampsia. The aim of this study was to investigate further the hypothesis that spiral artery endothelial cells can contribute to the mechanism of shallow trophoblast invasion.

METHOD

Fluorescently labeled Jar cells were added to monolayers of fluorescently-labeled endothelial cells that had been activated by treatment with TNFalpha, INF gamma or necrotic cell bodies. The ability of the Jars to displace endothelial cells from the monolayers was quantified by measuring the area of Jar cells "islands" formed in the endothelial cell monolayers by confocal microscopy and digital image.

RESULTS

The area of Jar cell islands formed in monolayers of activated endothelial cells was significantly smaller that the area of islands formed in control resting/non-activated endothelial cell monolayers regardless of the activator.

DISCUSSION

This work demonstrates that activated endothelial cells are more resistant to trophoblast displacement than resting endothelial cells and adds weight to the suggestion that endothelial cells could contribute to shallow invasion of the spiral arteries by trophoblasts in diseases such as preeclampsia.

Interaction of Jar choriocarcinoma cells with endothelial cell monolayers

During human pregnancy the uterine spiral arteries are invaded by placental trophoblasts which replace the endothelial cells that line the non-pregnant spiral arteries and transform these vessels into large-bore conduits enabling adequate perfusion of the placenta with maternal blood. Failure of this process may predispose to preeclampsia and fetal growth restriction [Brosens I, Robertson WB, Dixon HG. The physiological response of the vessels of the placental bed to normal pregnancy. Journal of Pathology and Bacteriology 1967;93:569-79; Khong TY, De Wolf F, Robertson WB, Brosens I. Inadequate maternal vascular response to placentation in pregnancies complicated by pre-eclampsia and by small-for-gestational age infants. British Journal of Obstetrics and Gynaecology 1986;93:1049-59]. There is a paucity of data on the role of maternal endothelial cells in this process. In this study we investigated the cellular interactions between trophoblast-derived Jar cells and endothelial cells (HUVECs and HMEC-1). The effect of coculturing Jar cells with endothelial cell monolayers was determined by confocal microscopy, DNA fragmentation assay and flow cytometry. We demonstrated that Jar cells migrate into focal areas in endothelial cell monolayers, where they induce endothelial cell death and, then phagocytose the dead endothelial cells. Our results suggest that endothelial cells may not simply be passive targets for invading trophoblasts during the remodeling of the spiral arteries.

Antiphospholipid antibodies bind to activated but not resting endothelial cells: is an independent triggering event required to induce antiphospholipid antibody-mediated disease?

INTRODUCTION

Antiphospholipid antibodies (aPL) cause thrombotic disease and recurrent pregnancy loss. Despite their name it is now clear that the antigen for most antiphospholipid antibodies is the phospholipid-binding protein beta(2) glycoprotein I (beta(2)GPI). However, beta(2) glycoprotein I is only antigenic for antiphospholipid antibodies when the protein is immobilised on a suitable surface such as phosphatidyl serine. It has been suggested that antiphospholipid antibodies bind to beta(2) glycoprotein I on the surface of resting endothelial cells and this in turn leads to endothelial activation and the initiation of thrombosis. However, as phosphatidyl serine is absent from resting endothelial cell membranes, we questioned this hypothesis.

MATERIALS AND METHODS

The ability of human antiphospholipid antibody-containing sera and monoclonal antiphospholipid antibodies to interact with endothelial cells was examined using cell-based ELISAs employing human umbilical vein endothelial cells (HUVECs) as the antigen. The expression of adhesion molecules in response to treatment with antiphospholipid antibodies was also measured by a cell-based ELISA. Activation of NF kappa beta was examined using electrophoretic mobility shift assays (EMSAs).

RESULTS

Neither monoclonal antiphospholipid antibodies nor human sera containing antiphospholipid antibodies bound to resting endothelial cells. In contrast, one monoclonal antiphospholipid antibody did bind to both activated and apoptotic endothelial cells.

CONCLUSIONS

Antiphospholipid antibodies do not bind to resting endothelial cells nor do antiphospholipid antibodies activate resting endothelial cells. Rather, an independent triggering event is required to activate endothelial cells and subsequently some antiphospholipid antibodies may then bind to the activated endothelial cells and initiate a thrombogenic process.

Perinatal predictors of growth patterns to 18 months in children born small for gestational age

AIM

To determine factors before or at birth that are predictive of growth patterns to 18 months in children born small for gestational age (SGA).

METHODS

Prospective cohort study of 186 SGA babies. Catch-up growth patterns were defined as early (>10th centile at 6 and 18 months), late (<10th centile at 6 months but >10th centile at 18 months), transient (>10th centile at 6 months but <10th centile at 18 months) or none (<10th centile at 6 and 18 months).

RESULTS

Most children (75%) showed catch-up growth by 6 months. Of antenatal variables studied, only early gestation at diagnosis of SGA predicted late or failed catch-up. Late or failed catch-up was also associated with short gestation, small absolute and relative size at birth, increased placental weight/birthweight ratio (Pl/BW) and prolonged neonatal hospital stay. On logistic regression, both late and failed catch-up were associated with short birth length. Late catch-up growth was also associated with prolonged hospital stay and male sex. Failed catch-up was associated with increased Pl/BW. No antenatal or perinatal variables distinguished early from transient catch-up groups.

CONCLUSION

SGA babies with late onset and less severe growth restriction have a good chance of catch-up growth by 6 months of age. Catch-up growth is likely to be delayed in SGA babies who are short at birth, are boys, and have prolonged hospital stays. However, poor growth over the first 6 months does not predict later growth patterns. Failure of catch-up growth in babies with increased Pl/BW may reflect an intrinsic growth defect. Transient catch-up growth may reflect environmental factors operating after birth.