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

Abstract

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 that 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, preterm birth, postterm 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 (ORs) were increased after bariatric surgery (all types combined) for perinatal mortality (1.38, 95% confidence interval [CI] 1.03–1.85, p = 0.031), congenital anomalies (1.29, 95% CI 1.04–1.59, p = 0.019), preterm birth (1.57, 95% CI 1.38–1.79, p < 0.001), and NICU admission (1.41, 95% CI 1.25–1.59, p < 0.001). Postterm birth decreased after bariatric surgery (OR 0.46, 95% CI 0.35–0.60, p < 0.001). ORs for SGA increased (2.72, 95% CI 2.32–3.20, p < 0.001) and LGA decreased (0.24, 95% CI 0.14–0.41, p < 0.001) after gastric bypass but not after gastric banding. Babies born after bariatric surgery (all types combined) weighed over 200 g less than those born to mothers without prior bariatric surgery (weighted mean difference −242.42 g, 95% CI −307.43 to −177.40 g, p < 0.001). There was low heterogeneity for all outcomes ( I ² < 40%) except LGA. Limitations of our study are that as a meta-analysis of existing studies, the results are limited by the quality of the included studies and available data, unmeasured confounders, and the small number of studies for some outcomes.

Conclusions

In our systematic review of observational studies, we found that bariatric surgery, especially gastric bypass, prior to pregnancy was 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 whether restrictive surgery results in better perinatal outcomes, compared to malabsorptive surgery, without compromising maternal outcomes. If so, these may be the preferred surgery for women of reproductive age.

Trial registration

PROSPERO CRD42017051537.

Abstract

Zainab Akhter and colleagues reveal that bariatric surgery for women prior to pregnancy can result in adverse outcomes for newborns, including intensive care admission and preterm birth

Author summary

Why was this study done?

• Obesity during pregnancy increases the risk of health complications for both mother and baby.

• Bariatric surgery before pregnancy improves obesity-related problems for the mother but reduces the absorption of micronutrients that are needed for healthy fetal development.

• This research aimed to investigate whether bariatric surgery is associated with adverse outcomes for the baby.

What did the researchers do and find?

• This systematic review included 33 studies that investigated perinatal outcomes among women with previous bariatric surgery compared to women without previous bariatric surgery.

• Meta-analysis identified a significant increase in odds of perinatal mortality, congenital anomalies, preterm birth, and neonatal intensive care unit admission but a decrease in odds of postterm birth after bariatric surgery.

• The odds of small babies were increased and the odds of large babies were decreased after malabsorptive bariatric surgery types, but there was no change for restrictive bariatric surgery types.

What do these findings mean?

• Bariatric surgery, in particular malabsorptive types of surgery, seems associated with an increased risk of some adverse perinatal outcomes, which suggests a link with nutrition.

• Women of reproductive age undergoing bariatric surgery are a high-risk group and require specialised preconception and antenatal nutritional support to achieve the best outcomes for both mothers and babies.