Background: Obesity is a widely spread health problem the complications of which are too many whether general or obstetric complications. Objective: The aim of this observational study is to evaluate the impact of increased BMI of nulliparous women on progress of labor, incidence of peri-partum complications (1ry outcome) and neonatal outcome of these women (secondary outcome). Patients and Methods: In this prospective observational study, 150 primigravidas in labor were recruited in Mit Ghamr General Hospital between November 1st, 2019 and April 30th, 2020 and categorized into 5 groups according to WHO BMI classification; Group A contained 50 patients with BMI 18.9-24.9, group B 50 patients with BMI 25-29.9, group C1 20 patients with BMI 30-34.9, group C2 20 patients with BMI 35-39.9 and group C3 10 patients with BMI at least 40. Recruited patients were monitored for their progress of labor (in terms of time of cervical dilation from 4 cm to 10 cm, the accordingly calculated rate of cervical dilation and duration of head descent) and their development of peri-partum complications (cervical dystocia, shoulder dystocia, arrest of head descent, the subsequent potential need for CS, 3rd and 4th degree perineal tears, 1ry post-partum hemorrhage, retained placenta). Neonatal outcome was observed by measuring fetal birth weight, APGAR score at 1 minute and 5 minutes, subsequent potential need for NICU admission and occurance of neonatal jaundice. Results: A statistically significant difference was found regarding progress of labor and neonatal outcome with women in obese groups (C1, C2, C3) having slower progress and worse neonatal outcome, while no statistically significant difference was found regarding mode of delivery and peri-partum complications. Conclusion: Obese women in labor considered high-risk cases that required special measures whether on short-term or long-term basis.