OBJECTIVE To evaluate the prevalence of first trimester vaginal bleeding among patients with abnormal second and third trimester uterine artery Doppler. METHODS A prospective study of patients with a uterine artery Doppler measurement between 27 and 42 weeks' gestation was undertaken. A comparison was made between two groups: patients with and without first trimester vaginal bleeding. Abnormal uterine artery Doppler was defined as PI >95th% or the presence of a diastolic notch. RESULTS Of the 277 patients that were included in the study, 65 (23%) had first trimester vaginal bleeding. No differences were noted in uterine artery Doppler waveforms among patients with and without first trimester vaginal bleeding. Among patients with first trimester vaginal bleeding, 9 (14%) had a bilateral uterine artery notch and 56 (86%) did not, compared with 51 (24%) and 161 (76%), in the control group, respectively. Patients with first trimester vaginal bleeding, and a bilateral uterine artery notch had significantly higher rates of small for gestational age neonates, low-Apgar scores (<7) at one minute and cesarean deliveries compared to patients with first trimester vaginal bleeding who did not have bilateral uterine artery notch. CONCLUSIONS First trimester vaginal bleeding was not associated with a higher incidence of abnormal uterine artery waveforms or with placental related conditions. However, adverse perinatal outcomes were found when first trimester vaginal bleeding was associated with second and third trimester bilateral uterine artery notchs.