Impact of Pre-Pregnancy Body Mass Index and Gestational Weight Gain on Pregnancy Complications and Outcomes

Objective: To assess impacts of pre-pregnancy BMI and gestational weight gain (GWG) on pregnancy complications and outcomes. Methods: This retrospective study analyzed 2488 pregnant women from Zhuzhou Central Hospital (2022). Participants were categorized by pre-pregnancy BMI (underweight, normal, overweight, obese) and GWG (insufficient, appropriate, excessive). Multivariate logistic regression evaluated associations with outcomes, adjusting for confounders. Results: Significant differences existed across BMI groups for age, parity, gestational diabetes (GDM), gestational hypertension (GHT), preterm birth, birth weight, cord entanglement, and delivery mode (all p<0.05). GWG significantly associated with age, parity, GDM, GHT, preterm birth, birth weight, and delivery mode (all p<0.05). After adjustment: Pre-pregnancy BMI: Underweight women had higher risks of preterm birth (OR=3.14, 95% CI:1.37-7.23) and GDM (OR=2.94, 95% CI:1.60-5.39). Overweight women had higher risks of GDM (OR=5.62, 95% CI:2.86-11.06) and GHT (OR=9.49, 95% CI:4.17-21.60). GWG: Insufficient gain increased risks of cesarean delivery (OR=1.48), low birth weight (LBW; OR=2.30), and macrosomia (OR=2.82). Excessive gain increased risks of preterm birth (OR=2.36), GDM (OR=1.52), GHT (OR=1.61), cesarean delivery (OR=1.57), LBW (OR=3.70), and macrosomia (OR=5.39) (all p<0.05 unless specified). Notably, obesity showed no significant associations. Maternal age >= 35 years independently increased preterm birth risk (OR=1.58), while high parity (>= 3) was protective (OR=0.75). Conclusion: Pre-pregnancy BMI and GWG significantly influence pregnancy complications and neonatal outcomes. Proper weight management may improve outcomes.