Impact of maternal pre-pregnancy body mass index on maternal, fetal and neonatal adverse outcomes in the worldwide populations: A systematic review and meta-analysis

Objective: Systematic review and meta-analysis conducted to investigate the effect of stratified pre-pregnancy maternal body mass index on twenty maternal and fetal/neonatal adverse outcomes. Methods: PubMed, Google Scholar, Medline, Embase, Web of Science databases were searched from inception till July 11, 2020. Cohort studies were included. The pooled odds ratio with 95% confidence interval was reported considering the random effect and the quality effect model. The sub-group analysis and meta-regression were conducted for BMI cut-offs, geographical region, source of BMI, and sample size. Results: Overall, 86 studies representing 20,328,777 pregnant women were included in this meta-analysis. Our study reveals that overweight and obese mothers are at increased odds of cesarean delivery, elective cesarean delivery, emergency cesarean delivery, gestational diabetes, gestational hypertension, induction of labor, post -partum hemorrhage, pre-eclampsia, pre-term premature rupture of membrane, and the fetuses/neonates of overweight and obese mothers are at increased risk of admission in the newborn intensive care unit, APGAR scores less than 7 at 5 min, large for gestational age, macrosomia, extreme pre-term birth in pregnant mothers compared with standard BMI mothers. However, the underweight mothers showed increased odds for small for gestational age infant and pre-term birth, whereas obese mothers were at higher risk for post-term birth and stillbirths. The subgroup and meta-regression analyses have shown the impact of BMI cut-offs, geographical region, source of BMI, and sample size on several maternal, fetal/neonatal adverse outcomes. Conclusion: The meta-analysis confirmed the association of elevated pre-pregnancy maternal BMI with higher odds of adverse maternal and fetal/neonatal outcomes.

Automated summary

The meta-analysis of 86 studies involving over 20 million pregnant women revealed that overweight and obese mothers have higher odds of experiencing adverse maternal and fetal/neonatal outcomes, while underweight and obese mothers also have different risks of adverse outcomes. Subgroup and meta-regression analyses further demonstrated the impact of BMI cut-offs, geographical region, source of BMI, and sample size on these outcomes.