Risk factors and primary indication for cesarean section in pregnant women with Gestational Diabetes Mellitus

Abstract

Gestational Diabetes Mellitus (GDM) is a common pregnancy complication and is linked to high cesarean rates, particularly in Brazil, where national data on the subject is limited. This study analyzed risk factors and primary indications for c-sections among GDM-affected pregnancies. It included a retrospective cohort of women receiving prenatal care at a tertiary hospital from January 2012 to March 2020, totaling 866 cases that met criteria: diagnosed GDM, pregnancies beyond 20 weeks, and delivery at this hospital. The cohort was divided into VAGINAL and CESAREAN groups, with statistical comparisons made between them. Of the 866 cases, 323 (37.3%) were vaginal deliveries, and 545 (62.7%) were c-sections. Primary indications for c-section included prior uterine surgeries (20.07%), iterative c-section (18.78%), fetal distress (9.76% intrapartum; 8.84% antepartum), non-cephalic presentation (7.37%), and functional dystocia (7.0%). Univariate analysis identified several factors associated with higher c-section risk, such as advanced maternal age (p<0.001), higher BMI (p=0.016), previous c-sections (p<0.001), hypertension (p=0.024), high glucose levels during pregnancy (p=0.031 for early fasting plasma glucose; p=0.002 for 1h and p<0.001 for 2h after glucose overload), nulliparity (p=0.012), multiple gestation (p<0.001), preeclampsia (p=0.012), and placenta previa (p=0.010). Conversely, spontaneous labor onset (p<0.001) and preterm labor (p=0.001) were associated with lower c-section rates. Multivariate analysis confirmed that age (OR 1,048), nulliparity (OR 2.892), previous c-section (OR 14.49), and spontaneous labor onset (OR 0.199) were independent predictors of c-section. The findings emphasize that prior uterine scars significantly increase c-section risk. In contrast, spontaneous labor onset reduces this risk by almost 80%.