Obstetric outcome in women with threatened miscarriage in the first trimester

OBJECTIVE: To assess pregnancy outcomes in women with threatened miscarriage in the first trimester. METHODS: This was a retrospective cohort study based on data extracted from the Aberdeen Maternity and Neonatal Databank. Cases included all primigravid women with first-trimester vaginal bleeding who delivered after 24 weeks of gestation between 1976 and 2004. The control group comprised all other women who had first pregnancies during the same period. Data were analyzed by univariate and multivariate statistical methods. RESULTS: Compared with the control group (n = 31,633), women with threatened miscarriage (n = 7,627) were more likely to have antepartum hemorrhage of unknown origin (odds ratio OR] 1.83, 95% confidence interval CI] 1.73-2.01). Elective cesarean (OR 1.30, 95% CI 1.14-1.48) and manual removal of placenta (OR 1.40, 95% CI 1.21-1.62) were performed more frequently in these women, who also had a higher risk of preterm delivery (OR 1.56, 95% CI 1.43-1.71) and malpresentation (OR 1.26, 95% CI 1.13-1.40). Threatened miscarriage in the first trimester is required in 112, 112, 17, 85, 32 patients, respectively, for each additional case of manual removal of placenta, elective cesarean, antepartum hemorrhage of unknown origin, malpresentation, and preterm delivery. CONCLUSION: Pregnancies complicated by threatened miscarriage are at a slightly higher risk of obstetric complications and interventions. LEVEL OF EVIDENCE: II-2.