Background: Threatened abortion is the incidence of first trimester bleeding from the uterus, characterized by closed os cervix and a viable fetus. As many cases of threatened abortion pregnancy continue until term, therefore it is crucial to determine the complications of threatened abortion. Objective: To evaluate the effect of threatened abortion on fetal growth, preterm premature rupture of membrane (PPROM), and adverse pregnancy outcomes as preterm labor, placenta previa, pregnancy-induced hypertension (PIH), intrauterine growth restriction (IUGR) and cesarean section. Patients and methods: One hundred ongoing pregnant cases who experienced first trimester threatened abortion and an age matched control group who had no threatened abortion signs until delivery were recruited in this prospective case-control study, and assessed for eligibility at the Outpatient Clinic and Causalities of the Obstetrics and Gynecology Department, Al-Monira  General Hospital from October 2018 till September 2019. Results: Adverse fetal outcomes were significantly higher among threatened abortion group in comparison with control group including the incidences of neonatal admission to NICU, preterm birth and low birth weight (p < 0.001), and IUGR (p=0.01). There were no significant differences between both groups regarding PPROM, PIH and placenta previa (p>0.05). Conclusion: The incidences of low birth weight, PROM, PIH, placental previa and IUGR rates increased in threatened abortion group in comparison with control group.