iarjimphIARJIMPHIARJIMPH2709-331X10.47310/iarjimph.2025.v06i01.003Impact of Maternal BMI and Gestational Weight Gain on Obstetric and Neonatal Outcomes: A Prospective Study on Risks and RecommendationsBackground: Maternal Body Mass Index (BMI) significantly impacts pregnancy outcomes. Underweight women face increased risks of anemia, Intrauterine Growth Restriction (IUGR), preterm birth, and low birth weight, while overweight women have higher incidences of gestational hypertension (PIH), Gestational Diabetes Mellitus (GDM), labor induction, cesarean delivery, and macrosomia. This study evaluates the effect of BMI and Gestational Weight Gain (GWG) on obstetric outcomes. Materials and Methods: A prospective observational study was conducted at Dr. Rajendra Prasad Government Medical College, Tanda, over one year (January-December 2019). 200 pregnant women with singleton pregnancies were categorized as underweight (BMI <18.5 kg/m²), normal weight (BMI 18.5-22.9 kg/m²), or overweight (BMI >23 kg/m²). Maternal and neonatal outcomes were analyzed using SPSS v21.0, with statistical significance set at p<0.05. Results: Among 200 women, 14% were underweight, 41% normal weight, and 45% overweight. Preterm birth was highest in underweight women (42.8%, p<0.0001), while PIH (27.7%, p = 0.024), GDM (11.1%), and labor induction (40%, p<0.0001) were significantly higher in overweight women. Low birth weight (<2.5 kg) was most common in underweight women (67.8%, p<0.0001), whereas macrosomia (>4 kg) occurred only in overweight women (5.6%, p = 0.049). Cesarean section rates were also highest in overweight women (24.7%) compared to normal BMI (23.1%) and underweight (7.1%). APGAR scores at 5 minutes were lower in underweight and overweight neonates compared to normal weight, but the difference was not statistically significant (p = 0.26). NICU admission rates were highest in underweight neonates (14.2%), followed by overweight (7.8%) and normal weight (4.8%), though this was not statistically significant (p = 0.26). Conclusion: Both low and high BMI adversely affect pregnancy outcomes, with underweight linked to IUGR and preterm birth, while overweight increases risks of PIH, GDM, macrosomia, and cesarean delivery. Preconception counseling, weight management, and close monitoring of gestational weight gain are crucial for improving maternal and neonatal health.