Background: Vaginal bleeding during pregnancy is one of the important causes of maternal, fetal and neonatal death. Women who remaine pregnant after vaginal bleeding, are at risk of complications such intrauterine fetal death (IUFD), intra uterine growth retardation (IUGR), preterm labor, placental abruption, preterm pre-labor rupture of membrane (PROM), and low birth weight.Methods: This prospective case–control study was done on 120 pregnant women, 60 with first trimester bleeding and 60 control ones, in Shariati hospital in Isfahan, Iran. All women were evaluated for pregnancy outcomes including bleeding in second and third trimester, abortion, preterm pre labor rupture of membrane, preterm labor, low birth weight, intra uterine growth retardation, mode of labor, APGAR coefficient in 5 minute, and neonatal intensive care unit (NICU) admission. Data was analyzed by Student t and c2 tests.Findings: There were no significant differences between groups in number of previous pregnancies and labors, number of children, history of abortion, premature rupture of membrane (PROM), intrauterine fetal death (IUFD), mod of labor, APGAR coefficient, neonatal intensive care unit admission and intra uterine growth retardation (IUGR) (P≥0.05). But placenta accreta, second trimester bleeding and preterm labor were significantly more in pregnant women with first trimester bleeding (P≤0.05).Conclusion: According to our results and other studies from other countries, first trimester bleeding could predict maternal and fetal complications. We recommend training pregnant women about these complications and their prevention.