The risk of intrapartum/neonatal mortality and morbidity following birth at 37 weeks of gestation: a nationwide cohort study

Neonatal mortality by gestational age in days in infants born at term: A cohort study in Sao Paulo city, Brazil

Birth at term comprises a period with heterogeneous neonatal outcomes that tend to be worse for infants born earlier. However, few studies have analyzed this period, in which each day can make a difference. Therefore, we aim to assess neonatal mortality (NM) according to gestational age (GA) at birth measured in days in term liveborn infants born in 2012-2017 in São Paulo, the largest city in Latin America. This population-based cohort study assessed term liveborn infants followed until the end of the neonatal period. We analyzed 7 models for NM according to GA in days: crude NM adjusted for maternal and prenatal variables, NM additionally adjusted for type of birth and type of hospital, and adjusted NM stratified by type of birth (cesarean and vaginal) and by type of hospital (public and private). We included 440,119 live infants born at 259-293 days of gestation. The median GA at birth was 274 days. In all models, NM was higher for infants born early term, decreasing in infants born full term and rising again in infants born late term. In the unadjusted model, hazard ratios of NM changed daily, decreasing from 3.34 to 1.00 on day 278 and increasing again thereafter. In the stratified analysis according to type of hospital, being born in a public hospital was associated with a reduced risk of NM for infants born at 278-283 days of pregnancy. There was a decrease in GA related to obstetric interventions, especially cesarean sections, which increased NM. The loss of days of pregnancy was larger in private hospitals. Increasing the granularity of GA to days is feasible and has the potential to drive public policies. To the best of our knowledge, this is the first Brazilian study on GA in days using a national live births database.

Maternal infections during pregnancy and child cognitive outcomes

Background

Maternal prenatal infections have been linked to children’s neurodevelopment and cognitive outcomes. It remains unclear, however, whether infections occurring during specific vulnerable gestational periods can affect children’s cognitive outcomes. The study aimed to examine maternal infections in each trimester of pregnancy and associations with children’s developmental and intelligence quotients. The ALSPAC birth cohort was used to investigate associations between maternal infections in pregnancy and child cognitive outcomes.

Methods

Infection data from mothers and cognition data from children were included with the final study sample size comprising 7,410 mother-child participants. Regression analysis was used to examine links between maternal infections occurring at each trimester of pregnancy and children’s cognition at 18 months, 4 years, and 8 years.

Results

Infections in the third trimester were significantly associated with decreased verbal IQ at age 4 (p < .05, adjusted R2 = 0.004); decreased verbal IQ (p < .01, adjusted R2 = 0.001), performance IQ (p < .01, adjusted R2 = 0.0008), and total IQ at age 8 (p < .01, adjusted R2 = 0.001).

Conclusion

Results suggest that maternal infections in the third trimester could have a latent effect on cognitive development, only emerging when cognitive load increases over time, though magnitude of effect appears to be small. Performance IQ may be more vulnerable to trimester-specific exposure to maternal infection as compared to verbal IQ. Future research could include examining potential mediating mechanisms on childhood cognition, such as possible moderating effects of early childhood environmental factors, and if effects persist in future cognitive outcomes.

Onset and outcomes of spontaneous labour in low risk nulliparous women

OBJECTIVES

The objective of this study was to: 1. Establish the median gestational age of spontaneous labour for low-risk nulliparas. 2. Examine the variation in mode of delivery and short-term neonatal outcomes with gestation at onset of spontaneous labour.

STUDY DESIGN

This is a retrospective observational cohort study conducted at a tertiary obstetric unit. The study population was 12, 323 low risk nulliparous women with singleton pregnancies who experienced spontaneous onset of labour. The study period was over seven years, from Jan 1st 2011 to 31st Dec 2017. Exclusion criteria were multiparity, multi-fetal pregnancy, booking after 14 weeks gestation, antepartum or intrapartum death, or any obstetric or fetal indication for delivery with the exception of post-maturity. Gestation of onset of spontaneous labour, demographic variables and maternal and neonatal outcomes were collected. The primary outcome was median gestational age at onset of spontaneous labour and its distribution at term. Secondary outcomes were mode of delivery and neonatal outcomes including low-apgar score and NICU admission.

RESULTS

12, 323 patients were eligible for inclusion. Median gestation for onset of labour was 40.1 weeks gestation, with 80.5% of spontaneous labour occurs by 41 + 0 weeks gestation. The risk of assisted delivery (RR 1.32, 95% CI 1.23 - 1.42), caesarean section (RR 2.17, 95% CI 1.88-2.51) and low-apgar scores (RR 3.13 95% CI 1.50-6.55) increased significantly with spontaneous labour after 41 weeks' gestation.

CONCLUSIONS

Nulliparous women with low-risk pregnancies are most likely to experience spontaneous labour between 40 + 0 and 40 + 6. 80.5% of spontaneous labour occurred by 41 + 0 weeks gestation. Assisted vaginal delivery, caesarean section and low-apgar scores were significantly more likely with spontaneous labour after 41 weeks' gestation.

Fetal umbilical artery Doppler as a tool for universal third trimester screening: A systematic review and meta-analysis of diagnostic test accuracy

The objective of this study was to investigate the accuracy of universal third trimester umbilical artery (UA) Doppler to predict adverse pregnancy outcome at term. We searched Medline, EMBASE, the Cochrane library and ClinicalTrials.gov from inception to October 2020 and we also analyzed previously unpublished data from a prospective cohort study of nulliparous women, the Pregnancy Outcome Prediction (POP) study. We included studies that performed a third-trimester ultrasound scan in unselected, low or mixed risk populations, excluding studies which only included high risk pregnancies. Meta-analysis was performed using the hierarchal summary receiver operating characteristic curve (HSROC) analysis and bivariate logit-normal models. We identified 13 studies (including the POP study) involving 67,764 pregnancies which met our inclusion criteria. The overall quality was variable and only six studies (N = 5777 patients) blinded clinicians to the UA Doppler result. The summary sensitivity and positive likelihood ratio (LR) for small for gestational age (SGA; birthweight <10th centile) were 21.7% (95% CI 13.2-33.6%) and 2.65 (95% CI 1.89-3.72) respectively. The summary positive LR for NICU admission and metabolic acidosis were 1.35 (95% CI 0.93-1.97) and 1.34 (95% CI 0.86-2.08) respectively. The results were similar in the POP study: associations with SGA (positive LR 2.66 [95% CI 2.11-3.36]) and severe SGA (birthweight <3rd centile; positive LR 3.27 [95% CI 2.29-4.68]) but no statistically significant association with neonatal morbidity. We conclude that third trimester UA Doppler has moderate predictive accuracy for small for gestational age but not for indicators of neonatal morbidity in unselected and low risk pregnancies.

Universal late pregnancy ultrasound screening to predict adverse outcomes in nulliparous women: a systematic review and cost-effectiveness analysis

BACKGROUND

Currently, pregnant women are screened using ultrasound to perform gestational aging, typically at around 12 weeks' gestation, and around the middle of pregnancy. Ultrasound scans thereafter are performed for clinical indications only.

OBJECTIVES

We sought to assess the case for offering universal late pregnancy ultrasound to all nulliparous women in the UK. The main questions addressed were the diagnostic effectiveness of universal late pregnancy ultrasound to predict adverse outcomes and the cost-effectiveness of either implementing universal ultrasound or conducting further research in this area.

DESIGN

We performed diagnostic test accuracy reviews of five ultrasonic measurements in late pregnancy. We conducted cost-effectiveness and value-of-information analyses of screening for fetal presentation, screening for small for gestational age fetuses and screening for large for gestational age fetuses. Finally, we conducted a survey and a focus group to determine the willingness of women to participate in a future randomised controlled trial.

DATA SOURCES

We searched MEDLINE, EMBASE and the Cochrane Library from inception to June 2019.

REVIEW METHODS

The protocol for the review was designed a priori and registered. Eligible studies were identified using keywords, with no restrictions for language or location. The risk of bias in studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. Health economic modelling employed a decision tree analysed via Monte Carlo simulation. Health outcomes were from the fetal perspective and presented as quality-adjusted life-years. Costs were from the perspective of the public sector, defined as NHS England, and the costs of special educational needs. All costs and quality-adjusted life-years were discounted by 3.5% per annum and the reference case time horizon was 20 years.

RESULTS

Umbilical artery Doppler flow velocimetry, cerebroplacental ratio, severe oligohydramnios and borderline oligohydramnios were all either non-predictive or weakly predictive of the risk of neonatal morbidity (summary positive likelihood ratios between 1 and 2) and were all weakly predictive of the risk of delivering a small for gestational age infant (summary positive likelihood ratios between 2 and 4). Suspicion of fetal macrosomia is strongly predictive of the risk of delivering a large infant, but it is only weakly, albeit statistically significantly, predictive of the risk of shoulder dystocia. Very few studies blinded the result of the ultrasound scan and most studies were rated as being at a high risk of bias as a result of treatment paradox, ascertainment bias or iatrogenic harm. Health economic analysis indicated that universal ultrasound for fetal presentation only may be both clinically and economically justified on the basis of existing evidence. Universal ultrasound including fetal biometry was of borderline cost-effectiveness and was sensitive to assumptions. Value-of-information analysis indicated that the parameter that had the largest impact on decision uncertainty was the net difference in cost between an induced delivery and expectant management.

LIMITATIONS

The primary literature on the diagnostic effectiveness of ultrasound in late pregnancy is weak. Value-of-information analysis may have underestimated the uncertainty in the literature as it was focused on the internal validity of parameters, which is quantified, whereas the greatest uncertainty may be in the external validity to the research question, which is unquantified.

CONCLUSIONS

Universal screening for presentation at term may be justified on the basis of current knowledge. The current literature does not support universal ultrasonic screening for fetal growth disorders.

FUTURE WORK

We describe proof-of-principle randomised controlled trials that could better inform the case for screening using ultrasound in late pregnancy.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42017064093.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 15. See the NIHR Journals Library website for further project information.

Analysis of Factors Associated With Variability and Acidosis of the Umbilical Artery pH at Birth

Background: Perinatal asphyxia is a significant contributing factor for neonatal morbidity and mortality. The aim of this study was to investigate the clinical factors associated with umbilical artery pH variability and fetal acidosis at birth. Methods: This is a single center cross-sectional study in a public regional hospital in southeastern Spain from January to December 2019. The reference population was 1.655 newborns, final sample of 312 experimental units with validated values of umbilical cord blood pH. Results: Factors such as gestational age at term ( X ¯ at - term : 7.26 ± 0.08- X ¯ no -_at-term: 7.31 ± 0.05, p: 0.00), primiparity ( X ¯ primiparity : 7.24 ± 0.078- X ¯ multiparity : 7.27 ± 0.08, p: 0.01), induced labor ( X ¯ induced : 7.24 ± 0.07- X ¯ spontaneous : 7.26 ± 0.081, p: 0.02), vaginal delivery ( X ¯ vaginal :7.25 ± 0.08- X ¯ cesarean :7.27 ± 0.07, p: 0.01), and prolonged dilation duration ( X ¯ AboveAverage : 7.22 ± 0.07- X ¯ BelowAverage : 7.27 ± 0.08, p: 0.00), expulsion duration ( X ¯ AboveAverage : 7.23 ± 0.07- X ¯ BelowAverage : 7.26 ± 0.08, p: 0.01), and total labor duration ( X ¯ AboveAverage : 7.23 ± 0.07- X ¯ BelowAverage : 7.27 ± 0.08, p: 0.00) are associated with a decrease in umbilical artery pH at birth. However, only three factors are associated with acidosis pH (<7.20) of the umbilical artery at birth: the induction of labor [OR: 1.74 (95% CI: 0.98-3.10); p: 0.04], vaginal delivery [OR: 2.09 (95% CI: 0.95-4.61); p: 0.04], and total duration of labor [OR: 2.06 (95% CI: 1.18-3.57); p: 0.01]. Conclusions: Although several factors may affect the variability of umbilical artery pH at birth by decreasing their mean values (gestational age, primiparity, induced labor, vaginal delivery and prolonged: dilation duration, expulsion duration and total labor duration), only induction of labor, vaginal delivery and total duration of labor are associated with an acidosis (<7.20) of same.

The risk of intrapartum/neonatal mortality and morbidity following birth at 37 weeks of gestation: a nationwide cohort study

Objective

To assess intrapartum/neonatal mortality and morbidity risk in infants born at 37 weeks of gestation compared with infants born at 39–41 weeks of gestation.

Design

Nationwide cohort study.

Setting

The Netherlands.

Population

A total of 755 198 women delivering at term of a singleton without congenital malformations during 2010–14.

Methods

We used data from the national perinatal registry (PERINED). Analysis was performed with logistic regression and stratification for the way labour started and type of care.

Main outcome measures

Intrapartum or neonatal mortality up to 28 days and adverse neonatal outcome (neonatal mortality, 5‐minute Apgar <7, and/or neonatal intensive care unit admission).

Results

At 37 weeks of gestation intrapartum/neonatal mortality was 1.10‰ compared with 0.59‰ at 39–41 weeks (P < 0.0001). Adjusted odds ratio (aOR) for 37 weeks compared with 39–41 weeks was 1.84 (95% CI) 1.39–2.44). Adverse neonatal outcome at 37 weeks was 21.4‰ compared with 12.04‰ at 39–41 weeks (P < 0.0001) with an aOR 1.63 (95% CI 1.53–1.74). Spontaneous start of labour at 37 weeks of gestation was significantly associated with increased intrapartum/neonatal mortality with an aOR of 2.20 (95% CI 1.56–3.10), in both primary (midwifery‐led) care and specialist care. Neither induction of labour nor planned caesarean section showed increased intrapartum/neonatal mortality risk.

Conclusions

Birth at 37 weeks of gestation is independently associated with a higher frequency of clinically relevant adverse perinatal outcomes than birth at 39–41 weeks. In particular, spontaneous start of labour at 37 weeks of gestation doubles the risk for intrapartum/neonatal mortality. Extra fetal monitoring is warranted.

Tweetable abstract

Birth at 37 weeks of gestation gives markedly higher intrapartum/neonatal mortality risk than at 39–41 weeks, especially with spontaneous start of labour.

Tweetable abstract

Birth at 37 weeks of gestation gives markedly higher intrapartum/neonatal mortality risk than at 39–41 weeks, especially with spontaneous start of labour.