Sleep is one of the most important activities of daily living affecting the life quality and health of individuals. Sleep disturbances are prevalent during pregnancy as a result of physical, physiological, and hormonal changes. The aim of this study was to evaluate the relationship between sleep duration of newborns and sleep quality of pregnant women in third trimester of pregnancy. The aim of this study was to evaluate the relationship between sleep duration of newborns and sleep quality of pregnant women in third trimester of pregnancy. Retrospective, longitudinal design. 147 pregnant  participated in the research. The pregnant women’s sleep quality was assessed by using Pittsburgh Sleep Quality Index in the 7th, 8th, and 9th months. Sleep duration of newborns was follow-up for 28 days and their daytime and night sleep duration was recorded. Pregnant women’s sleep quality decreased as gestation period progressed. Sleep quality mean score of the pregnant women were 4.24±2.78, 4.76 ±2.78 and 6.17±3.10 in the 7th, 8th, and 9th months, respectively (p<0.01). The extension of the transition period of pregnant women, sleep dysfunction in daytime increased sleep disturbances and sleep duration of newborns reduced. In the study, the correlation between sleeping latency and daytime dysfunction in the 7th month and the correlation between sleep disturbance and sleep duration of newborns in the 8th and 9th month were determined.