Background: Prenatal care needs to be focussed to reduce the adverse effects in pregnancy and improve the outcome. Prepregnancy obesity might be a risk factor for hypertensive disorder of pregnancy which causes fetal and maternal morbidity. Objective: To evaluate the relationship of prepregnancy body mass index (BMI) with the occurrence of hypertensive disorders of pregnancy (HDP). Method: The descriptive type of observational study was done at a tertiary care centre . Women were included in the study at their first visit before six weeks. The prepregnancy weight was used to calculate the BMI. Blood pressure measurements, routine examination and investigations were done at every visit. 45 women who developed HDP were considered as cases. Equal number of normotensive women were taken as controls. Data collected was analysed. Results: Out of 45 cases 57.7% were overweight, 31.1% were normal weight, 11.1% were underweight whereas of 45 controls, 20% were overweight, 55.55% were normal weight and 24.44% were underweight. The associations were statistically highly significant Conclusion: Since maternal obesity is a risk factor for it, prepregnancy reduction in weight would significantly help in reducing the risk of developing hypertension in pregnancy.