Risk of Severe Maternal Morbidity After Bariatric Surgery: Retrospective Cohort Study

We assessed whether bariatric surgery before pregnancy lowers the risk of severe maternal morbidity to a level comparable to no obesity.

Obesity is a risk factor for severe maternal morbidity, but the potential for bariatric surgery to reduce the risk has not been studied.

We analyzed a retrospective cohort of 2,412,075 deliveries between 1989 and 2019 in Quebec, Canada. The main exposure measures were bariatric surgery before pregnancy and obesity without bariatric surgery, compared with no obesity. The outcome was severe maternal morbidity, a composite of life-threatening pregnancy complications. We estimated risk ratios (RR) and 95% confidence intervals (CI) for the association between bariatric surgery and severe maternal morbidity, adjusted for maternal characteristics.

A total of 2654 deliveries (0.1%) were in women who had bariatric surgery, and 70,041 (29.0 per 1000) were in women who had severe maternal morbidity. Risk of severe maternal morbidity was not significantly elevated for bariatric surgery (RR 1.20; 95% CI 0.98-1.46), but was greater for obesity compared with no obesity (RR 1.60; 95% CI 1.55-1.64). Bariatric surgery was not associated with morbidities such as severe preeclampsia, sepsis, and cardiac complications compared with no obesity, but obesity was associated with elevated risks of these and other severe morbidities. Bariatric surgery was associated, however, with intensive care unit admission, compared with no obesity.

Pregnant women with prior bariatric surgery have similar risks as nonobese women for most types of severe maternal morbidity, except for intensive care unit admission.