First trimester vaginal bleeding (FTVB) does not usually terminate the pregnancy. However, its outcome is a matter of debate. This study sought to assess the outcomes of pregnancies, complicated by FTVB. In this cohort study, 236 gravida 1 and 2 FTVB patients with delivery after 28weeks of gestational age, admitted to Imam Hossein Hospital during 2009-2010, were evaluated. The control group consisted of 944 gravida 1 and 2 women without any history of vaginal bleeding. Late pregnancy outcomes such as gestational hypertension, preeclampsia, placental abruption, preterm delivery, and premature rupture of membranes in the mothers and low birth weight (LBW), intrauterine growth restriction(IUGR), Apgar score at 5min <7, and NICU admission in the infants were evaluated. Logistic regression was used for estimation of odds ratios (OR) and 95% confidence interval. Compared to controls, the FTVB cases had more premature rupture of membranes (OR=10), gestational hypertension (OR=5.3), and placental abruption (OR=4.7), while their infants had higher odds of LBW, IUGR, Apgar score at 5min <7, and admission to NICU too. The incidence of premature rupture of membranes was 3.6% in the controls and 27.1% in the cases (RR=10, P<0.001). The incidence of gestational hypertension and LBW was 1.5 and 7.2% (P<0.001) in the controls and 6.6 and 12.3% (P<0.001) in the cases. The other outcomes were similar in both groups. FTVB may play a role in the development of late pregnancy outcomes in mothers and infants. Thus, it is recommended to evaluate some interventions on FTVB cases to prevent complications.