ObjectiveThe aim of this study was to investigate and describe the use of medicinal plants during pregnancy among women admitted in the Maternity and Gynaecology wards at Jimma University Medical Centre (JUMC) in the southwest Ethiopia.DesignCross-sectional study.SettingMaternity and Gynaecology wards at JUMC.Participants1117 hospitalised pregnant women or postpartum women.Main outcome measuresOur primary outcomes of interest were the prevalence of use, types of medicinal plants used and their utilisation among pregnant women.MethodsData were collected through structured face-to-face interviews of pregnant women or postpartum women and review of patient medical records between February and June 2017.ResultsOverall, 28.6% of the women reported use of at least one medicinal plant during the pregnancy. Twenty-seven different types of medicinal plants were used. The most commonly used medicinal plants were Linum usitatissimum L. (flaxseed—use with caution) 22.0%, Ocimum lamiifolium L. (damakessie—safety unknown) 3.6% and Carica papaya L. (papaya—use with caution) 3.1%. The most common reason for use was preparation, induction or shortening of labour. Lack of access to health facility (mainly health posts), admission to maternity ward, khat chewing and alcohol consumption were the strongest predictors of medicinal plants use during pregnancy (OR >2). Only five medicinal plants used by women had sufficient evidence to be classified as safe to use in pregnancy.ConclusionsAlmost one-third of women at the tertiary hospital in Ethiopia reported use of medicinal plants during pregnancy, most frequently to prepare, induce, reduce the intensity or shorten duration of labour. Increased awareness about potential benefits or risks of medicinal plants use during pregnancy among healthcare professionals and patients, and increased access to childbirth providing healthcare facilities are important in order to promote safer pregnancies and better health outcomes for women and their unborn children.