Pregnancy after bariatric surgery and adverse perinatal outcomes: a systematic review and meta-analysis

Background

Women who undergo bariatric surgery prior to pregnancy are less likely to experience comorbidities associated with obesity such as gestational diabetes and hypertension. However, bariatric surgery, particularly malabsorptive procedures, can make patients susceptible to deficiencies in nutrients which are essential for healthy fetal development. The objective of this systematic review and meta-analysis is to investigate the association between pregnancy after bariatric surgery and adverse perinatal outcomes.

Methods and Findings

Searches were conducted in Medline, Embase, PsycINFO, CINAHL, Scopus, and Google Scholar from inception to June 2019; supplemented by hand-searching reference lists, citations, and journals. Observational studies comparing perinatal outcomes post-bariatric surgery to pregnancies without prior bariatric surgery were included. Outcomes of interest were: perinatal mortality, congenital anomalies, pre-term birth, post-term birth, small and large for gestational age (SGA/LGA), and neonatal intensive care unit (NICU) admission. Pooled effect sizes were calculated using random effects meta-analysis. Where data were available, results were subgrouped by type of bariatric surgery.

We included 33 studies with 14,880 pregnancies post-bariatric surgery and 3,979,978 controls. Odds ratios (OR) were increased after bariatric surgery (all types combined) for perinatal mortality (1.38, 95% CI 1.03–1.85), congenital anomalies (1.29, 95% CI 1.04–1.59), pre-term birth (1.57, 95% CI 1.38–1.79), and NICU admission (1.41, 95% CI 1.25–1.59). Post-term birth decreased after bariatric surgery (OR 0.46, 95% CI 0.35-0.60). ORs for SGA increased (2.72, 95% CI 2.32–3.20) and LGA decreased (0.24, 95% CI 0.14–0.41) after gastric bypass, but not after gastric banding. Babies born after bariatric surgery (all types combined) weighed over 200g less than those born to mothers without prior bariatric surgery (weighted mean difference -242.42g, 95% CI -307.43g to -177.40g). There was low heterogeneity for all outcomes (I2<40%) except LGA. As a meta-analysis of existing studies, the results are limited by the quality of the included studies and available data.

Conclusions

Bariatric surgery, especially gastric bypass, prior to pregnancy were associated with increased risk of some adverse perinatal outcomes. This suggests that women who have undergone bariatric surgery may benefit from specific preconception and pregnancy nutritional support and increased monitoring of fetal growth and development. Future studies should explore if restrictive surgery results in better perinatal outcomes than malabsorptive surgery without compromising maternal outcomes, and if so, these may be the preferred surgery for women of reproductive age.