Objectives: To compare antenatal complications, obstetric and neonatal outcome in underweight women and women with normal BMI.

Methodology: Prospective observational study. Subjects were selected from OPD and IPD for 6months in Government maternity hospital, Tirupati, using systematic random sampling. Their BMI at booking visit was noted. They were periodically followed results analysed.

Results: 106 women were underweight and 134 had normal BMI. Age distribution is similar.81.1% of the underweight women were anemic. 23.6% of underweight women and 9.7% of women with normal BMI developed gestational hypertension/ preeclampsia. Preterm labor (28.3%) and IUGR (22.3%) was significantly higher in underweight women.

 Conclusion: Underweight women have more incidence of anemia, blood transfusions, pregnancy induced hypertension, pre term labour and intrauterine growth retardation. The mean birth weight of baby is less in underweight women