Bariatric surgery associated with less pregnancy weight gain

Key takeaways:

• Women with bariatric surgery history gained less weight during pregnancy vs. women without.
• Pregnancy weight gain did not differ between gastric bypass or sleeve gastrectomy.

Women who had undergone bariatric surgery gained less weight during pregnancy compared with matched controls who did not have a history of bariatric surgery, according to study findings published in JAMA Network Open.

“Previous studies have found that women with a history of bariatric surgery, compared with those without such a history but otherwise similar presurgery characteristics, had lower risk of gestational diabetes, preeclampsia, large for gestational age birth and cesarean delivery, whereas the risks of small for gestational age and preterm birth were higher,” Huiling Xu, MD, MSc, from the clinical epidemiology division in the department of medicine at Karolinska Institute, Sweden, and colleagues wrote. “Pregnancy weight gain is associated with all these aforementioned outcomes and may also influence the association of bariatric surgery with adverse outcomes. However, the association of bariatric surgery with postoperative pregnancy weight gain is not well established.”

Xu and colleagues conducted a nationwide, population-based matched cohort study with data from 12,776 pregnant women, of whom 6,388 (mean age, 31.6 years) had a history of bariatric surgery and 6,388 (mean age, 31.4 years) were matched controls. From 2014 to 2021, singleton pregnancies with bariatric surgery history were matched to pregnancies without such history based on early pregnancy BMI, prepregnancy diabetes, prepregnancy hypertension, maternal age, smoking status, education level, height, country of birth and delivery year. Researchers also matched 890 post-gastric bypass pregnancies to 890 post-sleeve gastrectomy pregnancies.

The primary outcome was pregnancy weight gain.

Among women with a normal weight status, those with bariatric surgery history had lower weight gain z score during pregnancy (–0.23) compared with matched controls (0.1; adjusted difference, –0.33; 95% CI, –0.43 to –0.23). Compared with women without bariatric surgery history, researchers also noted lower weight gain z score during pregnancy among women with such history with:

• overweight (–0.32 vs. 0.01; adjusted difference, –0.33; 95% CI, –0.4 to –0.27);
• obese class I (–0.19 vs. 0.02; adjusted difference, –0.21; 95% CI, –0.29 to –0.13);
• obese class II (–0.22 vs. –0.06; adjusted difference, –0.16; 95% CI, –0.29 to –0.03); and
• obese class III (–0.16 vs. –0.08; adjusted difference, –0.08; 95% CI, –0.28 to 0.13).

Weight gain during pregnancy did not differ by surgical procedure. Researchers also observed that shorter surgery-to-conception interval or less surgery-to-conception weight loss was associated with lower weight gain during pregnancy.

“Women with a history of bariatric surgery gained less weight during pregnancy than those with similar BMI entering pregnancy, which may be attributable to physiological effects of altered anatomy and gut hormones, thereby reducing food intake and appetite,” the researchers wrote. “In addition, to prevent weight regain after bariatric surgery, women are often advised to avoid excessive pregnancy weight gain. However, we found that, compared with the controls, a higher proportion of women in the surgery group with a normal, overweight or obese class I status at the start of pregnancy gained below the pregnancy weight gain guidelines recommended by the [Institute of Medicine].”