Background: Low Birth Weight is a major public health problem since birth weight determines the health and development of a child. There are few studies that have reported that poor sleep quality in pregnancy is associated with adverse fetal outcome. Low Birth Weight is defined by World Health Organization as a neonate weighing less than 2500gm at birth irrespective of the gestational age. Low Birth Weight is the most common adverse fetal outcome that may lead to Perinatal mortality and morbidity. As per the National sleep foundation, about 78% women report sleep disturbance in pregnancy especially during third trimester. Aim:: To find out the association between the Sleep quality in late pregnancy and birth weight. Materials and methods: Using Pittsburg Sleep Quality Index (PSQI) questionnaire, Sleep quality for the last one month of pregnancy was assessed and Birth weight of the newborn was recorded from mother's hospital documents in 90 Postnatal mothers who had uneventful Antenatal Period. Association between the sleep quality in late pregnancy and the Birth weight was assessed. Results: The data obtained were analyzed using Statistical Package for Social Sciences (SPSS) version 20. 90 antenatal mothers whose age ranged from 18 to 40 years Participated in the study (M=24.94years, SD=4.42). Correlation coefficient between PSQI score of sleep quality and the birth weight is -0.05. Conclusion: The sleep quality in late pregnancy is inversely related to the birth weight which indicates that poor sleep quality during late pregnancy is a risk factor for Low birth weight. Hence, antenatal interventions to improve the sleep quality during pregnancy can be suggested for better fetal outcome.