Gestational Age-specific Risk Research Articles

Gestational age-specific clinical correlates of acute kidney injury in preterm infants with necrotizing enterocolitis.

To study the gestational age-specific risk factors and outcomes of severe acute kidney injury (AKI) in neonates with necrotizing enterocolitis (NEC). Retrospective cohort study comparing gestational age (GA)-specific clinical data between infants without severe AKI (stage 0/1 AKI) and those with severe AKI (stages 2 and 3 AKI) stratified by GA ≤27 and >27 weeks. Infants with GA ≤27 weeks had double the rate of severe AKI (46.3% vs. 20%). In infants with GA >27 weeks, male sex, outborn, and nephrotoxic medication exposure were associated with severe AKI. On multivariable logistic regression, in infants with GA ≤27 weeks, surgical NEC (OR 35.08 (CI 5.05, 243.73), p < 0.001) and ostomy (OR 6.2(CI 1.29, 29.73), p = 0.027) were associated with significantly higher odds of severe AKI. Surgical NEC infants with GA >27 weeks and severe AKI were significantly more likely to be outborn, have later NEC onset, need dopamine, and have longer hospitalization (158 days [110; 220] vs.75.5 days [38.8; 105]; p = 0.007 than those with non-severe AKI. In neonates with NEC, surgical intervention was associated with moderate-to-severe AKI in infants with GA ≤27 weeks and with longer hospitalization in infants with GA >27 weeks. In both cohorts need for surgery, stoma, cholestasis, and mechanical ventilation were associated with severe AKI; however, the infants with GA <27 weeks had twice the risk of severe AKI than GA >27 weeks group. The longer exposure to nephrotoxic medication and referral need were significant risk factors for AKI in GA >27 weeks group. GA-specific kidney protective and monitoring strategies to prevent AKI and its consequences are needed to improve the clinical outcomes in neonates with NEC. Understanding the risk factors and short- and long-term outcomes unique to different GA groups will help inform those strategies.

A flexible approach to modelling stillbirths using the foetuses at risk approach.

Survival analysis methods are increasingly used to model the gestational age-specific risk of perinatal phenomena such as stillbirth. To compare two types of survival analysis models, and highlight differences by estimating the relationships between pre-pregnancy BMI and gestational age-specific rates of stillbirth. The study was based on singleton live births and stillbirths in the United States in 2016-2017, with data obtained from the natality and fetal death files of the National Center for Health Statistics. We compared Cox regression versus piecewise exponential additive mixed models (PAMMs) for modelling the relationship between BMI and stillbirth across gestational age. In a second analysis, we illustrated the performance of both models for assessing the relationship between the trimester-specific number of cigarettes smoked, a time-dependent covariate, and stillbirth. The study population included 7,567,316 births, of which 42,739 were stillbirths (5.6 per 1000 total births). Stillbirth rates increased with increasing pre-pregnancy BMI and increasing gestational age. In analyses with BMI as a categorical variable, the Cox model and PAMM models yielded similar results. Analyses of BMI as a continuous variable also showed similar results when BMI associations were assumed to be linear, and the changes in gestational age-specific rates were modelled parametrically. However, results differed slightly when PAMMs, modelled with data-driven approaches, were used to estimate changes in BMI effects across gestational age; PAMMs provided a more nuanced modelling of time-varying effects. PAMM models showed an approximately linear increase in the effect of smoking on stillbirth with increasing gestational age. For survival analyses using the foetuses-at-risk approach, PAMMs provide a valuable alternative to the traditional Cox model, with increased modelling flexibility when proportional hazards assumptions are violated.

Retinopathy of prematurity: risk stratification by gestational age.

To identify gestational age (GA) specific risk factors for severe ROP (sROP). Single-center cohort stratified by GA into <24 weeks, 24-26 weeks and ≥27 weeks. 132/1106 (11.9%) developed sROP. Time to full feeds was the only risk factor [HR 1.003 (1.001-1.006), p = 0.04] for infants<24 weeks GA. For infants 24-26 weeks GA, a higher GA was protective [HR 0.66 (0.51-0.85), p < 0.01], whereas steroids for bronchopulmonary dysplasia (BPD) [HR 2.21 (1.28-3.26), p < 0.01], patent ductus arteriosus (PDA) ligation [HR 1.99 (1.25-3.11), p < 0.01] and use of nitric oxide [HR 1.96 (1.11-3.30), p = 0.01] increased the hazard of sROP. Increasing birthweight was protective [HR 0.70 (0.54-0.89), p < 0.01] in infants ≥27 weeks GA. Cumulative hazard of sROP reached 1.0 by fifteen weeks for <24 weeks GA, 0.4 by twenty weeks for 24-26 weeks GA, and 0.05 by twenty weeks after birth for ≥27 weeks GA. Risk factors, cumulative hazard, and time to sROP vary by GA.

Association between body-mass-index and gestational-age-specific rates of stillbirth in women with and without chronic hypertension

Body-mass-index (BMI) specific recommendations to inform optimal timing of delivery are scarce. This study describes gestational age-specific risks of stillbirth in women with varying pre-pregnancy BMI and assesses how these risks change in the presence of chronic hypertension (CH).

Diagnosis of fetal growth restriction in a cohort of small-for-gestational-age neonates at term: neonatal and maternal outcomes

Small-for-gestational-age neonates (birthweight of <10th percentile for gestational age) are significantly more likely to have multiple adverse outcomes than appropriate-for-gestational-age neonates (birthweight of 10th-90th percentile). Most small-for-gestational-age neonates are undetected during pregnancy (ie, not diagnosed as fetal growth restriction), but the sequela of being undetected remains uncertain. The primary objective of this study was to compare the composite neonatal adverse outcomes among singleton pregnancies that were at least 37 weeks and delivered small-for-gestational-age neonates, which were diagnosed as either fetal growth restriction during pregnancy (detected small for gestational age) or not (undetected small for gestational age). This was a secondary analysis of a retrospective cohort, the Consortium for Safe Labor. Singleton births at 37.0 to 41.6 weeks of gestation without congenital anomalies born small for gestational age were included in the analysis. The primary outcome was the rate of composite neonatal adverse outcome, defined as any of the following: Apgar score of <5 at 5 minutes, cardiopulmonary resuscitation at birth, respiratory distress syndrome, continuous positive airway pressure, mechanical ventilation, neonatal seizures, hypoxic-ischemic encephalopathy or diagnosis of asphyxia, intraventricular hemorrhage, necrotizing enterocolitis, neonatal sepsis, or fetal or neonatal death. The secondary outcome was the rate of composite maternal adverse outcome, which included any of the following: postpartum hemorrhage, peripartum infection, thromboembolism, hysterectomy, uterine rupture, eclampsia, intensive care unit admission, or maternal death. Small for gestational age with a prenatal diagnosis of fetal growth restriction (detected small for gestational age) was compared with small for gestational age without a prenatal diagnosis of fetal growth restriction (undetected small for gestational age). Multivariate logistic regression models were used to compare groups. A P value of <.05 was considered statistically significant. Gestational age-specific risks of composite neonatal adverse outcome and perinatal death were computed for each week of gestation among ongoing pregnancies. Of the 228,438 deliveries in the Consortium for Safe Labor, 18,607 (8.1%) met the inclusion criteria. Among these deliveries, 17,689 (95.0%) were undetected small for gestational age, and 918 (5.0%) were detected small for gestational age. The overall rate of composite neonatal adverse outcome was 3.0%. Moreover, the rate of composite neonatal adverse outcome was similar between undetected small for gestational age and detected small for gestational age (3.0% vs 3.9%, respectively; adjusted odds ratio, 1.33; 95% confidence interval, 0.88-2.00). Some components of the composite-respiratory distress syndrome, mechanical ventilation, and necrotizing enterocolitis-were significantly higher among undetected small for gestational age than among detected small for gestational age. The overall rate of composite maternal adverse outcome was 6.2%. The rate of composite maternal adverse outcome between undetected small for gestational age and detected small for gestational age (6.2% vs 5.1%, respectively; adjusted odds ratio, 0.84; 95% confidence interval, 0.60-1.18) was similar. In gestational age-specific comparisons of composite neonatal adverse outcome, no difference was found between the undetected small-for-gestational-age group and the detected small-for-gestational-age group except for in pregnancies >41 weeks. In pregnancies at 41.0 to 41.6 weeks, the rate of composite neonatal adverse outcome was significantly greater in detected small for gestational age than in undetected small for gestational age (10.0% vs 2.5%, respectively; P=.035). Antenatal detection of small for gestational age was not associated with improved composite neonatal adverse outcomes, although some components of morbidity improved with detection. Maternal outcomes did not differ between detected small for gestational age and undetected small for gestational age.

Stillbirth and neonatal mortality in a subsequent pregnancy following stillbirth: a population-based cohort study

BackgroundA history of stillbirth is a risk factor for recurrent fetal death in a subsequent pregnancy. Reported risks of recurrent fetal death are often not stratified by gestational age. In subsequent pregnancies increased rates of medical interventions are reported without evidence of perinatal benefit. The aim of this study was to estimate gestational-age specific risks of recurrent stillbirth and to evaluate the effect of obstetrical management on perinatal outcome after previous stillbirth.MethodsA retrospective cohort study in the Netherlands was designed that included 252.827 women with two consecutive singleton pregnancies (1st and 2nd delivery) between 1999 and 2007. Data was obtained from the national Perinatal Registry and analyzed for pregnancy outcomes. Fetal deaths associated with a congenital anomaly were excluded. The primary outcome was the occurrence of stillbirth in the second pregnancy stratified by gestational age. Secondary outcome was the influence of obstetrical management on perinatal outcome in a subsequent pregnancy.ResultsOf 252.827 first pregnancies, 2.058 pregnancies ended in a stillbirth (8.1 per 1000). After adjusting for confounding factors, women with a prior stillbirth have a two-fold higher risk of recurrence (aOR 1.96, 95% CI 1.07–3.60) compared to women with a live birth in their first pregnancy. The highest risk of recurrence occurred in the group of women with a stillbirth in early gestation between 22 and 28 weeks of gestation (a OR 2.25, 95% CI 0.62–8.15), while after 32 weeks the risk decreased. The risk of neonatal death after 34 weeks of gestation is higher in women with a history of stillbirth (aOR 6.48, 95% CI 2.61–16.1) and the risk of neonatal death increases with expectant obstetric management (aOR 10.0, 95% CI 2.43–41.1).ConclusionsA history of stillbirth remains an important risk for recurrent stillbirth especially in early gestation (22–28 weeks). Women with a previous stillbirth should be counselled for elective induction in the subsequent pregnancy at 37–38 weeks of gestation to decrease the risk of perinatal death.

856A gestational age specific prognostic model for adverse perinatal events in obese women

Abstract Background Obesity is one of the most preventable pre-pregnancy risk factors for adverse perinatal events. Despite this, there are few body-mass-index (BMI) specific prognostic models for timing of delivery associated with the lowest number of adverse perinatal events. Our aim was to build a predictive model to quantify gestational age-specific rates of adverse birth outcomes in obese women with and without additional risk factors. Methods All singleton births at ≥ 34 weeks’ gestation in British Columbia, Canada, 2008-2017 (n = 283,697) were included and data were obtained from the British Columbia Perinatal Database Registry. A multivariable Cox proportional hazards model including demographic and obstetric risk factors was used to estimate gestational age specific risk of composite perinatal mortality and severe morbidity. Results Among all women, 13.1% were obese (pre-pregnancy BMI ≥30m/kg2), 60.1% had normal BMI (18.5-24.9 m/kg2). In high-risk obese women (nulliparous with chronic hypertension, and diabetes), adjusted outcome rates (per 1000 ongoing pregnancies) were 7.5 at 34-36 weeks, 20.4 at 37-39 weeks, and 83.5 at ≥ 40 weeks’ gestation. In all obese women, the rates were 1.93, 6.27, and 18.5 per 1000 ongoing pregnancies, respectively. In contrast, on average these rates were 1.14, 4.03 and 11.6 per 1000 ongoing pregnancies, respectively, among women with normal BMI. Conclusions Obese women are at increased risk of poor perinatal outcomes at all gestational ages. These risks are compounded by other conditions known to effect perinatal outcomes. Key messages Obese women require specific guidelines for timing of optimal delivery.

Incidence and risk factors for severe preeclampsia, hemolysis, elevated liver enzymes, and low platelet count syndrome, and eclampsia at preterm and term gestation: a population-based study

The majority of previous studies on severe preeclampsia, eclampsia, and hemolysis, elevated liver enzymes, and low platelet count syndrome were hospital-based or included a relatively small number of women. Large, population-based studies examining gestational age-specific incidence patterns and risk factors for these severe pregnancy complications are lacking. This study aimed to assess the gestational age-specific incidence rates and risk factors for severe preeclampsia, hemolysis, elevated liver enzymes, and low platelet count syndrome, and eclampsia. We carried out a retrospective, population-based cohort study that included all women with a singleton hospital birth in Canada (excluding Quebec) from 2012 to 2016 (N=1,078,323). Data on the primary outcomes (ie, severe preeclampsia, hemolysis, elevated liver enzymes, and low platelet count syndrome, and eclampsia) were obtained from delivery hospitalization records abstracted by the Canadian Institute for Health Information. A Cox regression was used to assess independent risk factors (eg, maternal age and chronic comorbidity) for each primary outcome and to assess differences in the effects at preterm vs term gestation (<37 vs ≥37 weeks). The rates of severe preeclampsia (n=2533), hemolysis, elevated liver enzymes, and low platelet count syndrome (n=2663), and eclampsia (n=465) were 2.35, 2.47, and 0.43 per 1000 singleton pregnancies, respectively. The cumulative incidence of term-onset severe preeclampsia was lower than that of preterm-onset severe preeclampsia (0.87 vs 1.54 per 1000; rate ratio, 0.57; 95% confidence intervals, 0.53-0.62), the rates of hemolysis, elevated liver enzymes, and low platelet count syndrome were similar (1.32 vs 1.23 per 1000; rate ratio, 0.93; 95% confidence interval, 0.86-1.00), and the preterm-onset eclampsia rate was lower than the term-onset rate (0.12 vs 0.33 per 1000; rate ratio, 2.64; 95% confidence interval, 2.16-3.23). For each primary outcome, chronic comorbidity and congenital anomalies were stronger risk factors for preterm- vs term-onset disease. Younger mothers (aged <25 years) were at higher risk for severe preeclampsia at term and for eclampsia at all gestational ages, whereas older mothers (aged ≥35 years) had elevated risks for severe preeclampsia and hemolysis, elevated liver enzymes, and low platelet count syndrome. Regardless of gestational age, nulliparity was a risk factor for all outcomes, whereas socioeconomic status was inversely associated with severe preeclampsia. The risk for severe preeclampsia declined at term, eclampsia risk increased at term, and hemolysis, elevated liver enzymes, and low platelet count syndrome risk was similar for preterm and term gestation. Young maternal age was associated with an increased risk for eclampsia and term-onset severe preeclampsia. Prepregnancy comorbidity and fetal congenital anomalies were more strongly associated with severe preeclampsia, hemolysis, elevated liver enzymes, and low platelet count syndrome, and eclampsia at preterm gestation.

637 Gestational age specific risks for obese women with and without other risk factors

Obesity is one of the most preventable pre-pregnancy risk factors for adverse perinatal events. Despite this, there are few body-mass-index (BMI) specific prognostic models for timing of delivery associated with the lowest number of adverse perinatal events. Our aim was to build a model to estimate gestational age-specific rates of adverse perinatal outcomes in obese women with and without additional risk factors. This was a retrospective cohort study of all singleton births at ≥34 weeks’ gestation in British Columbia, Canada, 2008-2017. Data were obtained from the British Columbia Perinatal Database Registry. A multivariable Cox proportional hazards model including demographic and obstetric risk factors was used to estimate gestational age specific risk of composite perinatal mortality and severe morbidity for women at various weight classes. Interactions between obesity and other important risk factors were assessed on both the additive and multiplicate scales. Among all women (n=283,697), 13.1% were obese (pre-pregnancy BMI ≥30m/kg2), and 60.1% had normal BMI (18.5-24.9 m/kg2). As a fraction of ongoing pregnancies, adverse outcomes increased with increasing gestational age at delivery in women of all weights. There was a dose-response relationship with increasing BMI with those morbidly obese (BMI ≥ 40m/kg2) at the highest risk. Other key risk factors included nulliparity, chronic hypertension and diabetes mellitus. Obese women with any of these additional risk factors exhibited far worse outcomes than those without with increasing disparities at later delivery. There was additive interaction between nulliparity, chronic hypertension and diabetes mellitus and obesity, but no multiplicate interactions. Obese women are at increased risk of worse perinatal outcomes at all gestational ages. These risks are compounded by other known risk factors of adverse perinatal outcomes, especially closer to term.

Considering evidence in the management of fetal growth restriction.

Considering evidence in the management of fetal growth restriction.

Gestational age-specific risk of stillbirth during term pregnancy according to maternal age.

To investigate the gestational age-specific risk of stillbirth according to the maternal age group particularly regarding stillbirth risk at the end of pregnancy. This study was a retrospective national cohort study of all singleton term pregnancy using the Korean Vital Statistics database (n = 2,798,542). We evaluated the risk of stillbirth by gestational week in mothers aged 20-49years according to maternal age group and neonatal birth weight. The risk of stillbirth in women aged 41years and older was significantly higher than in women aged 20-29years between 37 and 40weeks' gestation. The stillbirth rate per 10,000 ongoing pregnancy in women aged 37-38years at 39weeks' gestation (4.22, 95% confidence intervals [CI] 3.01-5.90) and that in women aged 39-40years at 40weeks' gestation (8.15, 95% CI 4.83-13.77) were significantly higher in comparison with in those aged 20-29years at 39weeks' gestation (1.95, 95% CI 1.64-2.33) and at 40weeks' gestation (2.59, 95% CI 2.1-3,18). The risk of stillbirth showed an increasing pattern at 40 gestational weeks, in women aged 39years and older. Delivery plan need to be set up and supported to decrease rates of stillbirth at term in women aged 35years and older with other risk factors and in women aged 37years and older regardless of risk factors, and especially in women older than 40years of age.

Risk of stillbirth in low-risk singleton term pregnancies following fertility treatment: a national cohort study.

To assess the risk of stillbirth in low-risk in vitro fertilisation (IVF) pregnancies. Register-based national cohort study. Denmark 2003-2013. Cohort of 425 732 singleton pregnancies including 10 235 conceived following IVF/intracytoplasmic sperm injection (ICSI), 4521 conceived following intrauterine insemination (IUI), and 410 976 spontaneously conceived. Information on pregnancy, obstetrical risk factors, stillbirth, and fertility treatment was obtained from the Danish national health registers for all pregnancies after gestational week 21+6 . We estimated the overall and gestational age-specific risk of stillbirth in low-risk term pregnancies following IVF, ICSI, and IUI. Further, we estimated the association between stillbirth and IVF and ICSI respectively as well as fresh or frozen-thawed embryo transfer. Risk of stillbirth. The number of stillbirths in spontaneously conceived and IVF/ICSI low-risk term pregnancies was 525 (0.1%) and 35 (0.3%), respectively. In multivariate analysis, the risk of stillbirth in pregnancies following IVF/ICSI was increased (odds ratio 2.1, 95% CI 1.4-3.1). The risk of stillbirth was correspondingly increased in time-to-event analyses taking risk time for each fetus into account from gestational week 37 and onwards (hazard ratio 2.4, 95% CI 1.6-3.6). In sub-analyses, the risk of stillbirth was increased for pregnancies following ICSI (odds ratio 2.2, 95% CI 1.2-3.1), but not IVF (odds ratio 1.7, 95% CI 0.9-3.1). We found a systematically increased risk of stillbirth in low-risk term pregnancies following IVF/ICSI. Whether the risk was related to the treatment or to underlying subfertility is uncertain. The results may indicate a need for obstetrical surveillance for these pregnancies when reaching term. Increased risk of stillbirth in low-risk term pregnancies following fresh cycle IVF/ICSI.

Risk of fetal death with preeclampsia.

To estimate gestational age-specific risks of fetal death in pregnancies complicated by preeclampsia. Population-based cohort study comprising all singleton births (N=554,333) without preexisting chronic hypertension recorded in the Norwegian Medical Birth Registry from 1999 to 2008. Additional data come from a subset of preeclamptic pregnancies enrolled in the Norwegian Mother and Child Cohort Study with available medical records (n=3,037). The risk of fetal death, expressed per 1,000 fetuses exposed to preeclampsia, was calculated using a life table approach. Preeclampsia was recorded in 3.8% (n=21,020) of all pregnancies. Risk of stillbirth was 3.6 per 1,000 overall and 5.2 per 1,000 among pregnancies with preeclampsia (relative risk 1.45, 95% confidence interval [CI] 1.20-1.76). However, relative risk of stillbirth was markedly elevated with preeclampsia in early pregnancy. At 26 weeks of gestation, there were 11.6 stillbirths per 1,000 pregnancies with preeclampsia compared with 0.1 stillbirths per 1,000 pregnancies without (relative risk 86, 95% CI 46-142). Fetal risk with preeclampsia declined as pregnancy advanced, but at 34 weeks of gestation remained more than sevenfold higher than pregnancies without preeclampsia. For clinical purposes, the fetal risk of death associated with preeclampsia begins when preeclampsia becomes clinically apparent. Using a method that takes into account the clinical diagnosis of preeclampsia and the population of fetuses at risk, we find a remarkably high relative risk of fetal death among pregnancies diagnosed with preeclampsia in the preterm period. II.

Analyzing Risks of Adverse Pregnancy Outcomes

Approaches for analyzing the risks of adverse pregnancy outcomes have been the source of much debate and many publications. Much of the problem, in our view, is the conflation of time at risk with gestational age at birth (or birth weight, a proxy for gestational age). We consider the causal questions underlying such analyses with the help of a generic directed acyclic graph. We discuss competing risks and populations at risk in the context of appropriate numerators and denominators, respectively. We summarize 3 different approaches to quantifying risks with respect to gestational age, each of which addresses a distinct etiological or prognostic question (i.e., cumulative risk, prospective risk, or instantaneous risk (hazard)) and suggest the appropriate denominators for each. We show how the gestational age-specific risk of perinatal death (PND) can be decomposed as the product of the gestational age-specific risk of birth and the risk of PND conditional on birth at a given gestational age. Finally, we demonstrate how failure to consider the first of these 2 risks leads to selection bias. This selection bias creates the well-known crossover paradox, thus obviating the need to posit common causes of early birth and PND other than the study exposure.

Gestational age–specific risks vs benefits of multicourse antenatal corticosteroids for preterm labor

The purpose of this study was to estimate a gestational age threshold at which the benefits of treatment with weekly courses of antenatal corticosteroids (ACS) during preterm labor outweigh the risks. Risk-benefit ratios by gestational age were determined with the use of a Markov microsimulation decision-analysis model with a 1-week cycle length. Single course and multiple (weekly to a maximum of 4) courses of ACS by gestational age of entry (23 weeks to 31 weeks 6 days' gestation) were compared. Benefits were composite events (respiratory distress syndrome, chronic lung disease, severe intraventricular hemorrhage, periventricular leukomalacia, bronchopulmonary dysplasia, or stillbirth) averted. Risks were small head circumference and small for gestational age. More composite events are averted (benefits) than risks acquired (ratio, 6:1) when multiple courses of ACS are initiated at 26weeks' gestation. When multiple courses of ACS are initiated at 29weeks' gestation, the risk-benefit ratio is 1. Beyond 29 weeks, there is a suggestion of more risk than benefit. The model suggests that multiple courses of ACS that are initiated at <29 weeks' gestation may have increased benefit compared with risks. Further analyses are needed to determine the long-term clinical significance of these findings.

Risk factors for antepartum stillbirth and the influence of maternal age in New South Wales Australia: A population based study

BackgroundMaternal age is a known risk factor for stillbirth and delayed childbearing is a societal norm in developed country settings. The timing and reasons for age being a risk factor are less clear. This study aimed to document the gestational specific risk of maternal age throughout pregnancy and whether the underlying causes of stillbirth differ for older women.MethodsUsing linkage of state maternity and perinatal death data collections the authors assessed risk factors for antepartum stillbirth in New South Wales Australia for births between 2002 – 2006 (n = 327,690) using a Cox proportional hazards model. Gestational age specific risk was calculated for different maternal age groups. Deaths were classified according to the Perinatal Mortality Classifications of the Perinatal Society of Australia and New Zealand.ResultsMaternal age was a significant independent risk factor for antepartum stillbirth (35 – 39 years HR 1.4 95% CI 1.12 – 1.75; ≥ 40 years HR 2.41 95% CI 1.8 – 3.23). Other significant risk factors were smoking HR 1.82 (95% CI 1.56 –2.12) nulliparity HR 1.23 (95% CI 1.08 – 1.40), pre-existing hypertension HR 2.77 (95% CI 1.94 – 3.97) and pre-existing diabetes HR 2.65 (95% CI 1.63 – 4.32). For women aged 40 or over the risk of antepartum stillbirth beyond 40 weeks was 1 in 455 ongoing pregnancies compared with 1 in 1177 ongoing pregnancies for those under 40. This risk was increased in nulliparous women to 1 in 247 ongoing pregnancies. Unexplained stillbirths were the most common classification for all women, stillbirths classified as perinatal infection were more common in the women aged 40 or above.ConclusionsWomen aged 35 or older in a first pregnancy should be counselled regarding stillbirth risk at the end of pregnancy to assist with informed decision making regarding delivery. For women aged 40 or older in their first pregnancy it would be reasonable to offer induction of labour by 40 weeks gestation.

Preterm PROM

Preterm premature rupture of the membranes remains difficult to predict accurately. The majority of those suffering preterm premature rupture of the membrane lack risk factors that might lead to preventative treatments. Its management is centered on an evaluation of the risks and benefits of attempted pregnancy prolongation compared with expeditious delivery. An understanding of the gestational age specific risks for newborn morbidity and mortality is essential to estimate the potential benefits of conservative management. Once the diagnosis of membrane rupture remote from term is made, conservative management to reduce neonatal complications is generally attempted while maintaining vigilance for complications such as infection, umbilical cord compression, or abruption. Concurrent antibiotic therapy and antenatal corticosteroid treatment are typically administered to prolong pregnancy, prevent infection, and reduce gestational age dependent morbidities. Near and at term, particularly if fetal pulmonary maturity has been confirmed, the patient is generally best served by expeditious delivery.

Optimal timing of delivery in pregnancies with pre-existing hypertension

To determine the optimal timing of delivery in pregnancies with pre-existing (chronic) hypertension by quantifying the gestational age-specific risks of stillbirth associated with ongoing pregnancy and the gestational age-specific risks of neonatal mortality or serious neonatal morbidity following the induction of labour. Population-based cohort study. USA. A total of 171 669 singleton births to women with pre-existing hypertension between 1995 and 2005. Pregnancies additionally complicated by diabetes mellitus, cardiac, pulmonary or renal disease were excluded. The week-specific risks of stillbirth between 36 and 41 completed weeks of gestation were contrasted with the week-specific risks of neonatal mortality or serious neonatal morbidity among births following induction of labour in women with pre-existing hypertension. Stillbirth, neonatal mortality or serious neonatal morbidity (defined as a composite outcome which included any of the following: neonatal seizures, severe respiratory morbidity or 5-minute Apgar score ≤3). The risk of stillbirth in women with pre-existing hypertension remained stable at 1.0-1.1 per 1000 ongoing pregnancies until 38 weeks, before rising steadily to 3.5 per 1000 [95% confidence interval (CI): 2.4, 5.0] at 41 weeks. The risk of serious neonatal morbidity/neonatal mortality decreased sharply between 36 and 38 weeks from 137 [95% CI: 127, 146] to 26 [95% CI: 24, 29] per 1000 induced births, before stabilising beyond 39 weeks. Among women with otherwise uncomplicated pre-existing hypertension, delivery at 38 or 39 weeks appears to provide the optimal trade-off between the risk of adverse fetal and adverse neonatal outcomes.

441 Neonatal Morbidity in Moderately Preterm Infants. A Swedish National Population-Based Study

Objective: To determine the gestational age specific risks for neonatal morbidity, interventions and treatments in infants born at the crossroads between very and moderately preterm.Study design: A population-based Swedish study including 6,674 infants born at 30 to 34 weeks of gestational age (GA) during 2004-2008. Risks for neonatal morbidity and use of interventions were investigated with respect to GA and birth weight standard deviation scores.Results: Acute lung disorder was diagnosed in 28%, hypoglycemia in 16%, bacterial infection in 15% and hyperbilirubinemia in 59% of the moderately to very preterm infants. Thirty-eight percent were exposed to antenatal steroid therapy, 43% received nCPAP, 5.5% required mechanical ventilation, 5.2% were administered surfactant, and 30% received antibiotic therapy. The risks of neonatal diseases increased with decreasing GA, with odds ratios ranging from 2.1 to 23. Low birth weight for GA was more common at lower GA and was associated with increased risks for morbidity.Conclusions: Despite general advances in perinatal care, moderately preterm infants still face substantially increased risks for neonatal diseases, and these risks increase linearly as GA decreases. Whereas neonatal morbidity was similar to results of previous reports, management of respiratory problems was found to differ markedly from other studies.

Comparison of first‐trimester contingent screening strategies for Down syndrome

To assess the relative performance of a multi-stage first-trimester screening protocol for fetal Down syndrome. Data from 10,767 women who underwent combined ultrasound and biochemistry (BC) screening in the first trimester were reanalyzed using a contingent model approach. Amongst the 10,854 fetuses with known outcome, 32 had Down syndrome, 232 had other abnormalities and 10,590 were unaffected. Nuchal translucency (NT), BC and combined (NT-BC) gestational age-specific risks were calculated for each individual using The Fetal Medicine Foundation risk calculation algorithms (Mixture Model and Biochemistry). Individual patients were categorized as at low, high or intermediate risk according to one of the following three strategies. In 'Strategy-NT-BC' initial screening was performed using both NT and BC. In 'Strategy-BC' initial screening was undertaken using maternal serum markers followed by NT assessment in those with an intermediate risk (1 : 51 < risk <or= 1:1000) while in 'Strategy-NT' initial screening was undertaken using NT followed by serum marker assessment in those with an intermediate risk (1 : 51 < risk <or= 1:1000). The nasal bone was assessed in those with an intermediate risk as the final stage in each of the three strategies. Those with an adjusted risk of 1 in 100 or higher after nasal bone assessment were reclassified as high risk. Detection and false-positive rates were compared between differing strategies in our local population, and this analysis was also performed with the maternal age for our population standardized to the distribution found in England and Wales. In our local population the detection rate for a 5% false-positive rate using a combined screening policy (NT-BC) was 88% (95% CI, 75.3-98.9%), and 2.3% had an absent nasal bone. The respective detection rate and false-positive rate of the three multi-stage screening strategies were: Strategy-NT-BC: 87.5 and 2.5%; Strategy-BC: 87.5 and 5%; Strategy-NT: 84.4 and 2.9%. In the contingent Strategy-BC only 29% of those initially screened using serum markers required an NT scan. If the model were applied to a hypothetical obstetric population standardized to the maternal age distribution in England and Wales, the detection and false-positive rates of the same three screening strategies would be: Strategy-NT-BC: 86.2 and 1.9%; Strategy-BC: 82.8 and 4%; Strategy-NT: 75.8 and 2.3%, respectively. First-trimester contingent screening provides detection and false-positive rates comparable to those achieved using combined screening, but could be used to significantly reduce the number of scans performed.