EFFECTS OF PRE-PREGNANCY BODY MASS INDEX ON MODE OF DELIVERY

Abstract

Background: Pre-pregnancy body mass index (BMI) is an important determinant of maternal and neonatal outcomes. With the rising prevalence of overweight and obesity among women of reproductive age, understanding its impact on mode of delivery and pregnancy outcomes has become clinically relevant.

Objectives: To evaluate the effect of pre-pregnancy BMI on mode of delivery and to assess its association with maternal and neonatal outcomes among term pregnant women.

Methods: This hospital-based cross-sectional observational study was conducted in a tertiary care centre in Chennai among 90 term pregnant women. Pre-pregnancy BMI was calculated using first-trimester weight and categorized as underweight, normal, overweight, and obese based on WHO criteria. The primary outcome was mode of delivery, while secondary outcomes included maternal complications (postpartum haemorrhage, wound infection), neonatal outcomes (birth weight, Apgar score, NICU admission), and labour characteristics. Data were analysed using SPSS version 25, and associations were assessed using the Chi-square test, with p<0.05 considered statistically significant.

Results: Nearly half of the participants (46.6%) were overweight or obese. A significant association was observed between BMI and mode of delivery (p=0.003), with caesarean section rates increasing from 16.7% in underweight women to 75.0% in obese women. Failed induction and cephalopelvic disproportion were more common indications among higher BMI groups (p=0.032). Maternal complications such as postpartum haemorrhage (0% to 25.0%, p=0.018) and wound infection (0% to 18.8%, p=0.021) increased with BMI. Neonatal outcomes showed a progressive rise in mean birth weight (2.58 kg to 3.42 kg, p=0.001) and NICU admissions (0% to 31.3%, p=0.009), with a slight decline in Apgar scores (p=0.024). Labour duration was also prolonged with increasing BMI.

Conclusion: Increasing pre-pregnancy BMI is significantly associated with higher rates of caesarean delivery, maternal complications, and adverse neonatal outcomes. Early identification and optimization of maternal weight are essential to improve obstetric outcomes.