IntroductionIt is estimated that most people undergoing bariatric surgery are women of reproductive age; nonetheless, its effects on pregnancy outcomes are not yet fully understood.MethodsRetrospective observational study, conducted in a tertiary center in Portugal, included participants in two groups: (1) pregnant women with a history of bariatric surgery (n = 89) and (2) pregnant women with a BMI ≥ 35 kg/m2, without previous bariatric surgery (n = 176). Data was collected from the medical files. Multivariate analysis was conducted to adjust for confounders.ResultsPregnancy after bariatric surgery was associated with lower risk of gestational diabetes (15.7% vs. 30.1%, p = 0.002) and cesarean delivery (20.7% vs. 33.5%, p = 0.007), and a higher gestational weight gain (10.58 ± 9.95 vs. 7.33 ± 6.00 kg, p < 0.001). Participants in the bariatric surgery who experienced a gestational weight gain ≤ 10.0 kg had a higher risk of preterm delivery (16.7% vs. 2.5%, p = 0.031). No significant differences were found regarding hypertensive diseases of pregnancy between groups (4.5% vs 11.4%, p = 0.147).Pregnancy after bariatric surgery was associated with lower neonate weight percentile (34.24 ± 21.09 vs. 48.77 ± 27.94, p < 0.001), higher risk of fetal growth restriction (5.6% vs. 0.6%, p = 0.018), and lower risk of fetal macrosomia (0.0% vs. 7.5%, p = 0.005). There were no significant differences in the risk of SGA (12.5% vs. 7.0%, p = 0.127) or LGA neonates (2.3% vs. 6.4%, p = 0.069).ConclusionPregnancy after bariatric surgery is associated with both risks and benefits, which should be considered by healthcare providers. Pregnancy after bariatric surgery requires individualized care, to ensure adequate gestational weight and avoid micronutrient deficiencies.Graphical