Risks of stillbirth and neonatal death with advancing gestation at term: A systematic review and meta-analysis of cohort studies of 15 million pregnancies.

BACKGROUND: Despite advances in healthcare, stillbirth rates remain relatively unchanged. We conducted a systematic review to quantify the risks of stillbirth and neonatal death at term (from 37 weeks gestation) according to gestational age. METHODS AND FINDINGS: We searched the major electronic databases Medline, Embase, and Google Scholar (January 1990-October 2018) without language restrictions. We included cohort studies on term pregnancies that provided estimates of stillbirths or neonatal deaths by gestation week. We estimated the additional weekly risk of stillbirth in term pregnancies that continued versus delivered at various gestational ages. We compared week-specific neonatal mortality rates by gestational age at delivery. We used mixed-effects logistic regression models with random intercepts, and computed risk ratios (RRs), odds ratios (ORs), and 95% confidence intervals (CIs). Thirteen studies (15 million pregnancies, 17,830 stillbirths) were included. All studies were from high-income countries. Four studies provided the risks of stillbirth in mothers of White and Black race, 2 in mothers of White and Asian race, 5 in mothers of White race only, and 2 in mothers of Black race only. The prospective risk of stillbirth increased with gestational age from 0.11 per 1,000 pregnancies at 37 weeks (95% CI 0.07 to 0.15) to 3.18 per 1,000 at 42 weeks (95% CI 1.84 to 4.35). Neonatal mortality increased when pregnancies continued beyond 41 weeks; the risk increased significantly for deliveries at 42 versus 41 weeks gestation (RR 1.87, 95% CI 1.07 to 2.86, p = 0.012). One additional stillbirth occurred for every 1,449 (95% CI 1,237 to 1,747) pregnancies that advanced from 40 to 41 weeks. Limitations include variations in the definition of low-risk pregnancy, the wide time span of the studies, the use of registry-based data, and potential confounders affecting the outcome. CONCLUSIONS: Our findings suggest there is a significant additional risk of stillbirth, with no corresponding reduction in neonatal mortality, when term pregnancies continue to 41 weeks compared to delivery at 40 weeks. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42015013785.

Vaginal assessment and expedited amniotomy in oral misoprostol labor induction in nulliparas: a randomized trial.

BACKGROUND: Labor is induced in 20-30% of maternities, with an increasing trend of use. Labor induction with oral misoprostol is associated with reduced risk of cesarean deliveries and has a safety and effectiveness profile comparable to those of mechanical methods such as Foley catheter use. Labor induction in nulliparous women continues to be challenging, with the process often quite protracted. The eventual cesarean delivery rate is high, particularly when the cervix is unfavorable and ripening is required. Vaginal examination can cause discomfort and emotional distress particularly to nulliparous women, and plausibly can affect patient satisfaction with the induction and birth process. OBJECTIVE: The aim of this study was to evaluate regular (4-hourly prior to each oral misoprostol dose with amniotomy when feasible) compared with restricted (only if indicated) vaginal assessments during labor induction with oral misoprostol in term nulliparous women MATERIALS AND METHODS: We performed a randomized trial between November 2016 and September 2017 in a university hospital in Malaysia. Our oral misoprostol labor induction regimen comprised 50 µg of misoprostol administered 4 hourly for up to 3 doses in the first 24 hours. Participants assigned to regular assessment had vaginal examinations before each 4-hourly misoprostol dose with a view to amniotomy as soon as it was feasible. Participants in the restricted arm had vaginal examinations only if indicated. Primary outcomes were patient satisfaction with the birth process (using an 11-point visual numerical rating scale), induction to vaginal delivery interval, and vaginal delivery rate at 24 hours. RESULTS: Data from 204 participants (101 regular, 103 restricted) were analyzed. The patient satisfaction score with the birth process was as follows (median [interquartile range]): 7 [6-9] vs 8 [6-10], P = .15. The interval of induction to vaginal delivery (mean ± standard deviation) was 24.3 ± 12.8 vs 31.1 ± 15.0 hours (P = .013). The vaginal delivery rate at 24 hours was 27.7% vs 20.4%; (relative risk [RR], 1.4; 95% confidence interval [CI], 0.8-2.3; P = .14) for the regular vs restricted arms, respectively. The cesarean delivery rate was 50% vs 43% (RR, 1.1; 95% CI, 0.9-1.5; P = .36). When assessed after delivery, participants' fidelity to their assigned vaginal examination schedule in a future labor induction was 45% vs 88% (RR, 0.5; 95% CI, 0.4-0.7; P < .001), and they would recommend their assigned schedule to a friend (47% vs 87%; RR, 0.6; 95% CI, 0.5-0.7; P < .001) in the regular compared with the restricted arms, respectively. CONCLUSION: Despite a shorter induction to vaginal delivery interval with regular vaginal examination and a similar vaginal delivery rate at 24 hours and birth process satisfaction score, women expressed a higher preference for the restricted examination schedule and were more likely to recommend such a schedule to a friend.

Timing of planned cesarean delivery by racial group.

OBJECTIVE: To estimate the incidence of newborn respiratory distress syndrome (RDS) and transient tachypnea of the newborn (TTN) in relation to gestational age and planned cesarean delivery in white, South Asian, and black women. METHODS: Included in this study were 442,596 white, South Asian, and black women who delivered single live infants at 28 of weeks gestation onwards between 1988 and 2000. Using multiple logistic regression, the gestation-specific patterns of RDS for all deliveries and RDS plus TTN for deliveries by planned cesarean delivery were analyzed by racial group. The predictors of RDS from 37 weeks of gestation onwards were determined. RESULTS: More South Asians (28.2%, 95% confidence interval [CI] 27.8-28.6) and blacks (24.6%, 95% CI 24.0-25.1) delivered spontaneously before 39 weeks than whites (16.9%, 95% CI 16.8-17.1). Respiratory distress syndrome patterns by gestation differed significantly (P<.001). Compared with whites, the gestation-specific crude RDS rate was lower in South Asians up until 40 weeks and after adjusting for confounders; South Asians were most protected against RDS (odds ratio [OR] 0.6, 95% CI 0.5-0.9). The gestation-specific patterns of RDS plus TTN after planned cesarean delivery also differed significantly (P<.001) between racial groups. The lowest rate of TTN plus RDS was at 40 weeks for whites, but in South Asians and blacks, it was lowest at 38 weeks. CONCLUSION: The gestation-specific patterns of RDS differed significantly by racial group from 32 weeks of gestation onwards. Preterm black infants had a lower rate of RDS when compared with whites; also, South Asians had the lowest rate of transient tachypnea until 38 weeks and the lowest rate of RDS until 40 weeks of gestation. The advantages of waiting until 39 weeks to perform planned cesarean delivery for white women are not seen in South Asians or blacks.

Race, prematurity and immaturity.

Compared to white Europeans, Blacks and South Asians have a significantly shorter mean gestational length and a higher incidence of preterm birth. For any given gestational age before 37 weeks, Black and South Asian babies have less risk of respiratory distress syndrome, and the survival rate in Black babies is higher than white Europeans. From 37 weeks of gestation onwards, the perinatal mortality rate in Blacks is higher than in white Europeans, and this appears to be associated with a higher rate of meconium passage and respiratory morbidity. In full term South Asian babies, the late gestation rise in antepartum stillbirth occurs one week earlier than in white Europeans. These patterns remained significant even after adjusting for socioeconomic factors. This suggests that fetal maturity occurs earlier in gestation in Blacks and South Asians when compared to white European babies.

Maternal and fetal characteristics associated with meconium-stained amniotic fluid.

OBJECTIVE: To estimate the rates of meconium-stained amniotic fluid (AF) and adverse outcome in relation to gestational age and racial group, and to investigate the predictors of meconium-stained AF. METHODS: We studied 499,096 singleton births weighing at least 500 g, at 24 or more weeks of gestation, from 1988 to 2000. The predictors of meconium-stained AF from 37 weeks of gestation onward were determined using multiple logistic regression. RESULTS: The crude meconium-stained AF rates in preterm, term, and postterm births were 5.1% (95% confidence interval [CI] 4.9-5.4), 16.5% (95% CI 16.4-16.6), and 27.1% (95% CI 26.5-27.6), respectively; the rates in blacks, South Asians, and whites were 22.6% (95% CI 22.2-23.1), 16.8% (95% CI 16.5-17.1), and 15.7% (95% CI 15.6-15.8), respectively. Independent predictors of meconium-stained AF included being black (odds ratio [OR] 8.4, 95% CI 2.4-28.8), vaginal breech delivery (OR 4.7, 95% CI 4.2-5.3), being South Asian (OR 3.3, 95% CI 1.3-8.3), and being in an advancing week of gestation (OR 1.39, 95% CI 1.38-1.40). More blacks (17.9%, 95% CI 17.3-18.4) and South Asians (11.8%, 95% CI 11.5-12.1) with good outcome and no risk factors for fetal hypoxia had meconium-stained AF than did whites (11.2%, 95% CI 11.1-11.4). Using white neonates born at 40 weeks as reference, the absolute risk of adverse outcome at 41 and 42 weeks were 2% and 5% in whites, 3% and 7%, in South Asians, and 7% and 11% in blacks. CONCLUSION: Meconium-stained AF rates are different among races and across gestational age, and overall risk of adverse outcomes in meconium stained AF is low. LEVEL OF EVIDENCE: II.

Racial variation in the association between gestational age and perinatal mortality: prospective study.

OBJECTIVES: To determine if the risks of perinatal mortality and antepartum stillbirth associated with post term birth increase earlier during pregnancy in South Asian and black women than in white women, and to investigate differences in the factors associated with antepartum stillbirth between the racial groups. DESIGN: Prospective study using logistic regression analysis. SETTING: 15 maternity units in northwest London from 1988 to 2000. PARTICIPANTS: 197 061 nulliparous women self reported as white, South Asian, or black, who delivered a single baby weighing at least 500 g at 24-43 completed weeks' gestation. MAIN OUTCOME MEASURES: Gestation specific perinatal mortality, antepartum stillbirth rates, and independent factors for antepartum stillbirth by racial groups. Results The crude gestation specific perinatal mortality patterns for the three racial groups differed (P<0.001). The perinatal mortality rate among black women was lower than among white women before 32 weeks but was higher thereafter. Perinatal mortality was highest among South Asian women at all gestational ages and increased the fastest at term. After adjusting for the confounders of antepartum stillbirth (placental abruption, congenital abnormality, low birth weight, birth weight <10th centile, meconium passage, fever, maternal body mass index > or =30, and maternal age > or =30), the excess mortality among black women after 32 weeks was not significant. After adjusting for confounding, South Asian women still had a significantly higher risk of antepartum stillbirth (odds ratio 1.8, 95% confidence interval 1.2 to 2.7). Conclusions The risk of perinatal mortality increased earlier in gestation among South Asian women than among white women. The most important factor associated with antepartum stillbirth among white women was placental abruption, but among South Asian and black women it was birth weight below 2000 g.

Are reported preterm birth rates reliable? An analysis of interhospital differences in the calculation of the weeks of gestation at delivery and preterm birth rate.

We investigated the possibility of preterm birth misclassification as a determinant of variation in its reported rates. Using a database of 497,105 deliveries from 17 hospitals, the best estimate of gestational age made at delivery and entered into the database at that time was recalculated from the menstrual dates and mid-trimester ultrasound scan. The recalculated completed weeks of gestation at delivery was compared with that made at birth. Calculation of estimated gestational age varied between hospitals due to inconsistencies in 'rounding' and 'truncating' the weeks of gestation at delivery. This resulted in preterm birth misclassification rates of up to 10.1%.