Association between Gestational Weight Gain on Obstetric-Perinatal Outcomes Among Women With Pre-pregnancy Overweight or Obesity in a Peruvian Public Hospital

Objective To evaluate the association between excessive gestational weight gain (GWG) and obstetric and perinatal outcomes among women with pre-pregnancy excess weight attending a public hospital in Lima, Peru. Methods We conducted a retrospective cohort study using routinely collected institutional records from Hospital Maria Auxiliadora. Women with singleton pregnancies and pre-pregnancy body mass index (BMI) [≥]25 kg/m2 who delivered between January 2024 and August 2025 were included. Excessive versus non-excessive GWG was defined according to national guidelines. The primary outcome was a composite obstetric-perinatal outcome. Crude and adjusted relative risks (RRs) were estimated using Poisson regression with robust variance. Effect modification by pre-pregnancy BMI and maternal short stature was evaluated. Results Of 6082 records, 3118 met the eligibility criteria; 31.0% had excessive GWG. In adjusted analyses, excessive GWG was associated with a small increase in the risk of the composite outcome (aRR = 1.05; 95% CI: 1.01-1.09), but not with overall obstetric outcomes (aRR = 1.04; 95% CI: 0.99-1.09) or overall perinatal outcomes (aRR = 0.99; 95% CI: 0.85-1.15). The association varied according to pre-pregnancy BMI, with higher relative risks observed among women with obesity (classes I-III). Conclusions Among women with pre-pregnancy excess weight, excessive gestational weight gain was associated with a small increase in the risk of composite obstetric-perinatal outcomes but not with obstetric or perinatal outcomes analysed separately. The magnitude of the association differed across BMI categories, with stronger associations in higher obesity classes. These findings emphasise the importance of pre-pregnancy nutritional status when interpreting the potential impact of gestational weight gain on pregnancy outcomes.