Comparison of Maternal Labor-Related Complications and Neonatal Outcomes Following Elective Induction of Labor at 39 Weeks of Gestation vs Expectant Management: A Systematic Review and Meta-analysis

A double-blinded randomised controlled study of fluid restriction versus liberal fluid during induction of labour: A pilot study

BACKGROUND

Excess intravenous fluid for women requiring an induction of labour may adversely affect the duration of labour and maternal/neonatal outcomes.

AIMS

This study aimed to determine the difference in duration of labour and outcomes with a low background infusion rate, compared to liberal background intravenous fluid management.

MATERIALS AND METHODS

A double blind randomised controlled pilot study was performed on 200 women who underwent induction of labour at a single institution. Women were randomised to an intravenous rate of 40 mL/h versus 250 mL/h of Hartmann's solution. Fluid boluses were strictly controlled to limit bias. This trial was registered with the Australian clinical trial registry: ACTRN12621001298808.

RESULTS

Analysis of the total amount of fluid received showed good separation with Group 1 (40 mL/h) receiving 1,736 mL less than Group 2 (250 mL/h), median (interquartile range) 841 mL (458, 1691) versus 2,577 mL (1620, 4326) (P < 0.001). Median duration of labour was shorter in Group 1 by 24 min (P = ns). Subset analysis of nulliparous women showed that duration of labour was shorter in Group 1 by 83.5 min (P = ns).

CONCLUSION

As this was a pilot study, a significant difference in duration of labour or secondary outcomes was not seen. Given the increasing numbers of nulliparous women having an induction of labour, potential for adverse maternal and neonatal outcomes and the associated higher rate of operative birth, this study guides power calculations and supports proof of concept for future research into optimum fluid management during induction of labour for these women.

Prediction of Failure to Progress after Labor Induction: A Multivariable Model Using Pelvic Ultrasound and Clinical Data

Objective: Labor induction is one of the leading causes of obstetric admission. This study aimed to create a simple model for predicting failure to progress after labor induction using pelvic ultrasound and clinical data. Material and Methods: A group of 387 singleton pregnant women at term with unruptured amniotic membranes admitted for labor induction were included in an observational prospective study. Clinical and ultrasonographic variables were collected at admission prior to the onset of contractions, and labor data were collected after delivery. Multivariable logistic regression analysis was applied to create several models to predict cesarean section due to failure to progress. Afterward, the most accurate and reproducible model was selected according to the lowest Akaike Information Criteria (AIC) with a high area under the curve (AUC). Results: Plausible parameters for explaining failure to progress were initially obtained from univariable analysis. With them, several multivariable analyses were evaluated. Those parameters with the highest reproducibility included maternal age (p < 0.05), parity (p < 0.0001), fetal gender (p < 0.05), EFW centile (p < 0.01), cervical length (p < 0.01), and posterior occiput position (p < 0.001), but the angle of descent was disregarded. This model obtained an AIC of 318.3 and an AUC of 0.81 (95% CI 0.76-0.86, p < 0.0001) with detection rates of 24% and 37% for FPRs of 5% and 10%. Conclusions: A simplified clinical and sonographic model may guide the management of pregnancies undergoing labor induction, favoring individualized patient management.

Placental pathology and neonatal morbidity: exploring the impact of gestational age at birth

AIM

To evaluate placental pathology in term and post-term births, investigate differences in clinical characteristics, and assess the risk of adverse neonatal outcome.

METHODS

This prospective observational study included 315 singleton births with gestational age (GA) > 36 weeks + 6 days meeting the local criteria for referral to placental histopathologic examination. We applied the Amsterdam criteria to classify the placentas. Births were categorized according to GA; early-term (37 weeks + 0 days to 38 weeks + 6 days), term (39 weeks + 0 days to 40 weeks + 6 days), late-term (41 weeks + 0 days to 41 weeks + 6 days), and post-term births (≥ 42 weeks + 0 days). The groups were compared regarding placental pathology findings and clinical characteristics. Adverse neonatal outcomes were defined as 5-minute Apgar score < 7, umbilical cord artery pH < 7.0, admission to the neonatal intensive care unit or intrauterine death. A composite adverse outcome included one or more adverse outcomes. The associations between placental pathology, adverse neonatal outcomes, maternal and pregnancy characteristics were evaluated by logistic regression analysis.

RESULTS

Late-term and post-term births exhibited significantly higher rates of histologic chorioamnionitis (HCA), fetal inflammatory response, clinical chorioamnionitis (CCA) and transfer to neonatal intensive care unit (NICU) compared to early-term and term births. HCA and maternal smoking in pregnancy were associated with adverse outcomes in an adjusted analysis. Nulliparity, CCA, emergency section and increasing GA were all significantly associated with HCA.

CONCLUSIONS

HCA was more prevalent in late and post-term births and was the only factor, along with maternal smoking, that was associated with adverse neonatal outcomes. Since nulliparity, CCA and GA beyond term are associated with HCA, this should alert the clinician and elicit continuous intrapartum monitoring for timely intervention.

Pregnancy outcomes after implementation of an induction of labor care pathway

BACKGROUND

Induction of labor is common; however, the optimum clinical strategy for induction of labor is less clear. Variations in clinical practices related to induction of labor may lead to increased complications and longer induction of labor times.

OBJECTIVE

This study aimed to analyze whether the implementation of an evidence-based standardized care pathway improves the clinical outcomes associated with induction of labor.

STUDY DESIGN

This was an approved quality improvement project implementing a clinical care pathway for induction of labor. Moreover, this was a retrospective cohort study of inductions of labor for 5 months before (January 2018 to May 2018) and 14 months after (August 2018 to September 2019) the implementation of the care pathway. The primary outcome was time from admission to delivery. Time from admission to delivery was stratified by mode of delivery. The secondary outcomes included chorioamnionitis, endometritis, neonatal intensive care unit admissions, cesarean delivery, postpartum hemorrhage, and a composite of unanticipated outcomes (chorioamnionitis, endometritis, neonatal intensive care unit admissions, cesarean delivery, and postpartum hemorrhage). In addition, pathway adherence was analyzed. The outcomes were analyzed using 2-tailed t tests for continuous data and the Fisher exact test and chi-square tests for categorical data. Propensity score matching was used to assess for confounding by potential covariates.

RESULTS

A total of 1471 inductions of labor were reviewed, with 392 inductions of labor before the implementation of the care pathway and 1079 inductions of labor after the implementation of the care pathway. The pathway was associated with a nonsignificant reduction in the time from admission to delivery by 1.2 hours (from 23.4 to 22.2 hours; P=.08). There was a nonsignificant increase in the time to cesarean delivery before (28.2 hours) and after (28.8 hours) protocol implementation (P=.71). There was a significant decrease in the time to delivery by 1.7 hours for vaginal deliveries (from 22.2 to 20.5 hours) after protocol implementation (P=.02). There was a significant decrease in chorioamnionitis (from 12.5% to 6.0%; odds ratio, 0.44; 95% confidence interval, 0.29-0.67), a significant decrease in endometritis (from 6.9% to 2.6%; odds ratio, 0.36; 95% confidence interval, 0.20-0.65), and a significant decrease in composite unanticipated outcomes (from 56.9% to 36.6%; odds ratio, 0.46; 95% confidence interval, 0.34-0.56) after the implementation of the care pathway. There was no significant difference in postpartum hemorrhage (from 7.9% to 6.1%; odds ratio, 0.76; 95% confidence interval, 0.48-1.22), neonatal intensive care unit admissions (from 18.1% to 14.0%; odds ratio, 0.74; 95% confidence interval, 0.54-1.02), or cesarean deliveries (from 19.6% to 20.1%; odds ratio, 1.03; 95% confidence interval, 0.76-1.40) after the implementation of the care pathway. Pathway adherence varied, ranging from 50% to 89%.

CONCLUSION

The introduction of a standardized induction of labor pathway was associated with a nonsignificant reduction in the time from admission to delivery by 1.2 hours and improved pregnancy outcomes, including decreased infections and unanticipated outcomes. Further opportunities for improvements in clinical outcomes may be realized with increased compliance with the care pathway.

Educational Outcomes for Children at 7 to 9 Years of Age After Birth at 39 vs 40 to 42 Weeks' Gestation

Importance

Birth at 39 weeks' gestation is common and thought to be safe for mother and neonate. However, findings of long-term outcomes for children born at this gestational age have been conflicting.

Objective

To evaluate the association of birth at 39 weeks' gestation with childhood numeracy and literacy scores at ages 7 to 9 years compared with birth at 40 to 42 weeks' gestation.

Design, Setting, and Participants

In this Australian statewide, population-based cohort study using a causal inference framework based on target trial emulation, perinatal data on births between January 1, 2005, and December 31, 2011, were linked to educational outcomes at 7 to 9 years of age. Statistical analyses were performed from December 2022 to June 2023.

Exposure

Birth at 39 weeks' gestation compared with birth at 40 to 42 weeks' gestation.

Main Outcomes and Measures

Numeracy and literacy outcomes were assessed at 7 to 9 years of age using Australian National Assessment Program-Literacy and Numeracy data and defined by overall z score across 5 domains (grammar and punctuation, reading, writing, spelling, and numeracy). Multiple imputation and doubly robust inverse probability weighted regression adjustment were used to estimate population average causal effects.

Results

The study population included 155 575 children. Of these children, 49 456 (31.8%; 24 952 boys [50.5%]) were born at 39 weeks' gestation and were compared with 106 119 (68.2%; 52 083 boys [49.1%]) born at 40 to 42 weeks' gestation. Birth at 39 weeks' gestation was not associated with altered educational outcomes for children aged 7 to 9 years compared with their peers born at 40 to 42 weeks' gestation (mean [SE] z score, 0.0008 [0.0019] vs -0.0031 [0.0038]; adjusted risk difference, -0.004 [95% CI, -0.015 to 0.007]). Each educational domain was investigated, and no significant difference was found in grammar and punctuation (risk difference [RD], -0.006 [95% CI, -0.016 to 0.005]), numeracy (RD, -0.009 [95% CI, -0.020 to 0.001]), spelling (RD, 0.001 [95% CI, -0.011 to 0.0013]), reading (RD, -0.008 [95% CI, -0.019 to 0.003]), or writing (RD, 0.006 [95% CI, -0.005 to 0.016]) scores for children born at 39 weeks' gestation compared with those born at 40 to 42 weeks' gestation. Birth at 39 weeks' gestation also did not increase the risk of scoring below national minimum standards in any of the 5 tested domains.

Conclusions and Relevance

Using data from a statewide linkage study to emulate the results of a target randomized clinical trial, this study suggests that there is no evidence of an association of birth at 39 weeks' gestation with numeracy and literacy outcomes for children aged 7 to 9 years.