The association between previous single first trimester abortion and pregnancy outcome in nulliparous women

Objective: To determine the association between single previous abortion and pregnancy outcome in nulliparous women.Methods: A retrospective cohort study of all nulliparous women who delivered in a university-affiliated tertiary hospital (2009-2014). Pregnancy outcome of women with single previous first trimester abortion (study group) was compared to those of primigravida (control group).Results: Of the 44 371 deliveries during the study period, 14 498 (32.6%) were of nulliparous women, of them 1501 (10.3%) had single previous abortion (<13 weeks). Except for a higher rate of diabetes mellitus in the study group (6.1 versus 4.4%, p = 0.003), no differences were found between the groups regarding pregnancy complications. In multivariate analysis, previous single abortion was independently associated with induction of labor (OR = 1.31, 95%C.I 1.04-1.63, p = 0.01), cesarean section (OR = 1.38, 95%C.I 1.18-1.60, p < 0.001) and retained placenta (OR = 1.29, 95%C.I 1.03-1.61, p = 0.02). Among nulliparous women with previous single abortion no difference in pregnancy outcome was observed between those with previous induced termination of pregnancy and spontaneous abortion, except for increased risk for retained placenta in those with previous spontaneous abortion.Conclusion: Single early previous abortion in nulliparous women was associated with higher rate of induction of labor, cesarean section and retained placenta compared to primigravida women.