Background: High BMI is associated with an increased risk of preeclampsia, gestational hypertension, macrosomia, induction of labour, caesarean deliveries and poor perinatal outcomes.Low BMI has been shown to be associated with an increased risk of preterm deliveries, low birth weight and anemia and a decreased risk of preeclampsia, gestational diabetes, obstetric intervention and postpartum haemorrhage. Aim & Objective: 1. To assess correlation between maternal Body Mass Index (BMI) and perinatal outcome. Methods: Study design: Prospective observational Study. Study setting: Department of Obstetrics and Gynaecology, Nowrosjee Wadia Maternity Hospital, Mumbai (NWMH), (Tertiary Health Centre). Study population: patients who delivered / underwent completion of pregnancy at the institute such cases were included in the study. Sample size: 100 Results: The highest number of patients belonged to the age group of 23-28 yr (61%%), followed closely by the age group of 29-35 yr (33%). Patient between age group 18-22 yr was only 6%. LSCS was performed in 48%, out of which Emergency LSCS constituted 40% & Elective LSCS constituted 8%. P-value for LSCS was 0.001 & for Emergency LSCS was 0.003 suggesting these are more common in BMI Group III & IV. Instrumental Deliveries were performed in 4% of patients out of which Forceps applied in 2% & Vacuum extraction done in 2% patients. Out of 90 patients, in 7 (7.78%) patients second stage of labour was prolonged. Meconium-stained liquor was found more commonly in BMI Group III with P-value for 0.028. Total of 25 patients were diagnosed to be suffering from gestational hypertension. 5 (20%) of them had postpartum haemorrhage & Blood Transfusion was needed in 3 (12%) them. Foetal Distress was found to be the most common complications affecting 18% of patients who participated in this study. P-value for Foetal Distress is 0.011 suggesting significant association being more common in BMI Group IV. Neonatal complications respiratory distress syndrome & Meconium Aspiration Syndrome were found in 4 % & 3% babies without any significant association in any of the BMI group. Conclusion: Vaginal Delivery was the most common obstetric outcome, Neonatal outcome was Live Birth among all the patients.