Impact of gestational weight gain on perineal injury in overweight and obese primiparous women

OBJECTIVE: Overweight and obesity are associated with adverse pregnancy outcomes, yet higher body mass index (BMI) has paradoxically been linked to reduced risk of perineal lacerations, including obstetric anal sphincter injury (OASI). The role of gestational weight gain (GWG) in this context is not well established. The objective of this study was to evaluate the association between GWG and perineal injury among overweight and obese primiparous women. METHODS: . Women were categorized by GWG based on Institute of Medicine guidelines: below (Group A), within (Group B), or above recommendations (Group C). Exclusion criteria included cesarean delivery, diabetes, multiple gestations, stillbirth, preterm birth, non-vertex presentation, and maternal age < 18 or > 45 years. Perineal injury was defined as any perineal laceration or episiotomy. Univariate and multivariable logistic regression analyses were performed. RESULTS: Among 5,082 deliveries, 13.1% were in Group A, 28.2% in Group B, and 58.7% in Group C. Episiotomy rates were higher in Group C versus Groups A/B (38.7% vs. 34.7%/34.5%; p = 0.011), while overall perineal injury (87.2%-88.5%, p = 0.652) and OASI rates (0.5-1.0%, p = 0.428) did not differ. In multivariate analysis, GWG was not associated with perineal injury. Independent risk factors included epidural analgesia (OR = 1.39, 95% CI 1.10-1.75), vacuum-assisted delivery (VAD) (OR = 2.83, 95% CI 2.07-3.86), higher birthweight (OR = 1.06 per 100 gr., 95% CI 1.03-1.08), and advanced gestational age (OR = 1.13, 95% CI 1.04-1.23). CONCLUSION: GWG was not associated with perineal injury, whereas VAD, epidural analgesia, increased birthweight, and advanced gestational age were independent risk factors.