Risk factors for preterm birth in pregnancies following bariatric surgery: an analysis of the Longitudinal Assessment of Bariatric Surgery-2

Abstract

Background: Bariatric surgery has been shown to increase the risk for preterm birth in a subsequent pregnancy. Determining factors that contribute to this heightened risk will inform the development of targeted interventions to improve birth outcomes postbariatric surgery.

Objectives: This study aimed to identify risk factors of preterm birth in pregnancies following bariatric surgery. Factors being considered were preoperative medical conditions and behaviors (e.g., obesity-associated co-morbidities, gastrointestinal symptoms, substance use), antenatal factors (e.g., prepregnancy body mass index, gestational weight gain), and surgery-specific factors (e.g., surgery type, surgery-to-conception interval).

Setting: Bariatric surgery centers in the United States.

Methods: This is a retrospective analysis of the Longitudinal Assessment of Bariatric Surgery-2. Participants were women who reported at least 1 singleton live birth during the 7-year postoperative period. Logistic regressions were used to identify risk factors of preterm birth, adjusting for covariates such as maternal age, race, and ethnicity.

Results: Participants (n = 97) were mostly White (84.5%) and non-Hispanic (88.7%). At the time of surgery, the mean age was 29.4 ± 4.6 years, and the mean body mass index was 47.6 ± 6.3 kg/m². The prevalence of preterm birth was 13.4%. Preoperative gastrointestinal symptoms significantly increased (odds ratio: 1.12; 95% confidence interval: 1.00-1.26), while unexpectedly, excessive versus adequate gestational weight gain (odds ratio: .12; 95% confidence interval: .02-1.00) decreased the odds of preterm birth following bariatric surgery.

Conclusions: This analysis identified potential risk and protective factors of preterm birth among pregnancies postbariatric surgery. However, given the small sample size, findings should be regarded as hypothesis-generating and merit further study.

Keywords: Bariatric surgery; Gastrointestinal symptoms; Gestational weight gain; Longitudinal Assessment of Bariatric Surgery-2; Preterm birth.