Maternal obesity, more than diabetes mellitus, predisposes to soft tissue injuries of the birth canal during vaginal delivery.

Abstract

Objectives: The purpose of this study was to evaluate the relationship between the incidence of birth canal soft tissue injuries, perineal incision procedure and maternal and neonatal characteristics.

Material and methods: It was a retrospective cohort study conducted in a tertiary hospital analyzing deliveries between July 2018 and January 2019. Study group included 726 spontaneous vaginal singleton births in the longitudinal cephalic fetal position after completed 36th gestational week. Characteristics of patients who suffered from cervical ruptures and/or vaginal injuries were compared to those who gave birth without any soft tissue traumas.

Results: The perineal incision procedure was performed in 561 (77.3%) women. Soft tissue injuries of the birth canal were found in 220 patients (30.3%). Cervical rupture was more frequent when perineal incision was performed (94.5% vs 74.2%, p = 0.0001), but only in primiparous women (70.6% vs 43.2%, p = 0.01). Vaginal injury happened less frequently when perineal incision was performed (56.5% vs 81.8%, p = 0.001), but only in multiparous women (12.9% vs 34.3%, p = 0.001). Vaginal injury was more common in women with higher pre-pregnancy body weight (69.4 vs 65.4 kg, p = 0.0015), higher prepregnancy BMI (24.5 vs 23.5 kg/m², p = 0.0085), higher body weight and BMI before delivery (82.2 vs 78.1 kg, p = 0.001 and 29.1 vs 28.1 kg/m², p = 0.008, respectively). In multivariate logistic regression analysis neither parity nor perineal incision increased the risk of vaginal injury. Only the obese women, but not diabetic, were at higher risk of vaginal injury, when perineal incision was performed (OR 2.25, CI 1.25-4.05, p = 0.007).

Conclusions: The obese women are at higher risk of vaginal injury during delivery, when perineal incision is performed. The necessity of maintaining normal body weight while planning pregnancy, monitoring gestational weight gain, and avoiding perineal incision remain important issues.