Bariatric Surgery, Gestational Diabetes and Perinatal Outcomes: A Population-Based Study

To examine the independent and combined associations of metabolic and bariatric surgery (MBS) and gestational diabetes mellitus (GDM) with adverse maternal and neonatal outcomes.

Population-based retrospective cohort study.

New South Wales (NSW), Australia.

Four hundred twenty-nine thousand five hundred seventy-six singleton births from 2016 to 2020 in NSW, including 3001 women with a history of MBS.

Linked perinatal and hospital data were used to classify women into four groups: no MBS/no GDM, MBS/no GDM, GDM/no MBS, and GDM/MBS. Multivariable logistic regression was used to examine associations with adverse outcomes, adjusting for maternal age, BMI, parity, smoking, country of birth, and gestational age.

Neonatal and maternal outcomes including preterm birth, (large-for-gestational-age) LGA, small-for-gestational-age (SGA), neonatal hypoglycaemia, preeclampsia and postpartum haemorrhage.

Women with both GDM and prior MBS had the highest odds of adverse outcomes. Compared to women without GDM or surgery, this group had increased odds of LGA (aOR 1.42, 95% CI 1.22-1.65), preterm birth (aOR 1.93, 95% CI 1.52-2.42), and neonatal hypoglycaemia (aOR 4.98, 95% CI 4.22-5.84). Preeclampsia risk was modestly increased across all groups but attenuated after BMI adjustment. Postpartum haemorrhage was reduced in women with prior surgery (aOR 0.81, 95% CI 0.72-0.92), while induction of labour was more likely in all exposure groups.

gestational diabetes mellitus (GDM) and prior MBS confer independent and combined risks for adverse perinatal outcomes. These findings support the need for personalised antenatal care strategies in this high-risk population.