Bariatric surgery may increase risk for pregnancy, birth complications

Women who become pregnant after bariatric surgery are nearly three times more likely to deliver an infant small for gestational age when compared with women who did not undergo surgery, in addition to increased risks for preterm birth, perinatal mortality and congenital abnormalities, according to data presented at the European Congress on Obesity.

“Our findings indicate that women with a history of bariatric surgery, and in particular gastric bypass surgery, are at much greater risk of several adverse perinatal outcomes,” Zainab Akhter, a doctoral student from Newcastle University, United Kingdom, said in a press release. “These women require specific preconception and pregnancy nutritional support. This highlights the importance of dietary supplements and extra monitoring of fetal growth and development. Health professionals also need training and guidance to be able to provide the right advice.”

In a systematic review and meta-analysis, Akhter and colleagues analyzed data from 33 observational studies assessing the association between pregnancy after bariatric surgery and some adverse perinatal outcomes, including 14,880 pregnancies after bariatric surgery and 3,979,978 pregnant women who did not undergo surgery. Outcomes of interest were perinatal mortality, congenital anomalies, preterm birth, post-term birth, small for gestational age, large for gestational age and neonatal ICU admission. Random-effects meta-analysis was carried out for all outcomes. Subgroup analysis was carried out by type of surgery where possible.

In random-effects meta-analysis, researchers found that pregnancy after bariatric surgery increased the risk for preterm birth (OR = 1.57; 95% CI, 1.38-1.79), neonatal ICU admission (OR = 1.41; 95% CI, 1.25-1.59), perinatal mortality (OR = 1.38; 95% CI, 1.03-1.85) and congenital anomalies (OR = 1.29; 95% CI 1.04-1.59).

Women who became pregnant after bariatric surgery were 54% less likely to deliver later than term vs. women who did not undergo surgery (OR = 0.46; 95% CI, 0.35-0.6); however, the risk for delivering an infant small for gestational age nearly tripled (OR = 2.72; 95% CI, 2.32-3.2), according to researchers.

In analysis stratified by surgery type, researchers found that risk for delivering an infant large for gestational age decreased for women who became pregnant after undergoing gastric bypass (OR = 0.24, 95% CI, 0.14-0.41), but not after gastric banding.

The researchers also found that infants born after bariatric surgery weighed approximately 200 g less than infants born to mothers who did not undergo bariatric surgery (weighted mean difference, –242.4 g; 95% CI, –307.4 to –177.4).

“It is not clear how weight-loss surgery may influence fetal development, but we know that people who have bariatric surgery are more likely to have micronutrient deficiencies,” Akhter said in the release. “More work needs to be done to better understand the causes of these differences, so that steps can be taken to support women to achieve the best possible pregnancy outcomes for themselves and their babies.” – by Regina Schaffer

Reference:

Akhter Z, et al. Adverse perinatal outcomes associated with pregnancy after bariatric surgery: A systematic review and meta-analysis. Presented at: European Congress on Obesity; April 28-May 1, 2019; Glasgow, Scotland.

Disclosures: The authors report no relevant financial disclosures.