Hypertension and diabetes mellitus disorders are the leading cause of death and initiative of other diseases at the time of delivery or pregnancy. It can lead to maternal, neonatal or fetal morbidity or mortality in all over the world. Therefore, the study has been conducted to determine the effect of hypertension and diabetes mellitus on adverse perinatal outcomes and the study have been conducted in tertiary centers. The frequency of hypertension as well as diabetes mellitus has been explored in the study in pregnancy and its association was found with gestational age and stillbirth. Objective: The study was conducted to find frequency of hypertension and diabetes mellitus on pregnancy and its association with gestational age and stillbirth. Study Design: The population-based study was conducted for the analysis of effect of hypertension and diabetes mellitus on pregnancy and the duration of study was five months from August 2019 to December 2019. Methodology: A prospective population-based observation study was conducted for 1st delivery. The data of almost 150 pregnant women was collected who were experiencing hypertension and diabetes mellitus at the time of pregnancy. It was also found in the study either the pregnancy and these conditions have any association or not. Results: It was determined in the study that pregnancy is associated with many complications from which most common are diabetes mellitus and hypertension. The result showed that the age of about 76 out of 150 pregnant women who were dealing with hypertension at the time of pregnancy and the age was range from 31-40. The study also showed that age is also linked with diabetes mellitus during pregnancy such as most of the women 76 out of 150 patients were dealing with diabetes mellitus during gestational period. Conclusion: It was concluded from the results that age is highly associated with various diseases especially hypertension and diabetes mellitus at the time of pregnancy. These diseases are the leading cause of other morbidities as well as mortalities for both mother and neonatal. It is important to handle the situation and take good care about these diseases especially during pregnancy. Key Words: Hypertension, Diabetes Mellitus, Gestational age, Stillbirth, maternal, fetal, neonatal mortality and morbidity.