Sleep is a physiological process and vital for the normal physical and mental well-being of an individual . Sleep disorder is one of the most common type’s mental illnesses, directly related to the thoughts, feelings, and behaviors of humans. Pregnancy is the term given to a woman while her fetus develops inside her uterus . It causes many physical, social, economic, psychological, and hormonal changes contributing to develop different forms of mental illness for a short and long periodSleep is a natural physiological process vital for the physical and mental wellbeing of pregnant women and their fetuses. Even though poor sleep quality is a common problem among pregnant women, it is not studied in developing countries including Ethiopia. Therefore, this study was aimed to assess the poor sleep quality and associated factors among pregnant women attending antenatal care at Jimma medical center, Jimma, Southwest Ethiopia, 2020. A cross-sectional study design was conducted among 415 pregnant women at Jimma Medical Center (JMC). The study subjects were selected using a systematic random sampling technique. Pittsburgh Sleep Quality Index (PSQI) was used to assess sleep quality using face-to-face interviews. SPSS version 25 was used to analyze data. Bivariate and multivariable logistic regressions were done to identify factors related to sleep quality. In multivariable logistic regression variables with a p-value less than 0.05 was considered significant and, adjusted OR (AOR) with 95% CI was used to present the strength of the association.