Bariatric surgery associated with better health for mothers, but not without risk

Updated: Aug 3

A study of more than 20,000 Kaiser Permanente members in Southern California showed that women with obesity who underwent bariatric surgery prior to pregnancy experienced improved outcomes such as a reduced risk of serious pregnancy-related blood pressure conditions, and lower instances of a new-born needing to be sent to the neonatal intensive care unit (NICU). However, there also were some increased risks of heavy bleeding and small babies. The outcomes were featured in the study, ‘Perinatal Outcomes After Bariatric Surgery’, published online in the American Journal of Obstetrics & Gynecology.

“We evaluated moms who had undergone vertical sleeve gastrectomy, which is the most prevalent bariatric surgical procedure used in the United States,” said the study’s lead author, Dr Darios Getahun, an investigator with the Kaiser Permanente Southern California Department of Research & Evaluation. “We found that bariatric surgery may decrease the risk of NICU admission by nearly 30% and may significantly decrease the risk of several serious outcomes. However, bariatric surgery also was associated with increased risk of a mom having heavy bleeding after the birth, and babies who are born small for their gestational age.”


The study showed many clear benefits for women who became pregnant after bariatric surgery, but also the potential for some poor outcomes that are important for physicians and patients to understand before birth to reduce risks.


Bariatric surgery was associated with a:

· 47% reduced risk for preeclampsia (p<0.001)

· 40% reduced risk for gestational diabetes (p<0.001)

· 76% reduced risk for macrosomia (when a baby is born much larger than average for gestational age)

· 55% reduced risk for chorioamnionitis (p<0.001)

· 35% reduced risk for caesarean section (p<0.001)

· 146% increased risk for small-for-gestational-age birth

· 79% increased risk for postpartum haemorrhage


A growing number of women are becoming pregnant after bariatric surgery, a treatment for obesity that can provide long-term weight control and health benefits. For this study, Kaiser Permanente researchers compared pregnant women who had bariatric surgery at some time before their pregnancy to pregnant women who were eligible for bariatric surgery but had not had it. Among the 20,213 eligible women who had become pregnant between January 2007 and December 2018, 9.3%, or 1,886, had bariatric surgery prior to pregnancy.


“Kaiser Permanente has done extensive research on bariatric surgery and its benefits,” said Dr Karen J Coleman, the senior author of the study and an investigator with the Kaiser Permanente Southern California Department of Research & Evaluation. “This was our first study showing the benefit of bariatric surgery for women who intend to get pregnant. It is very important for women who are considering pregnancy in the future to talk to their physicians about what they need to do now to prepare to have the healthiest baby possible. Our findings suggest that for women with severe obesity, one of those options may be bariatric surgery, but this decision would need to be made in collaboration with their physician.”