Bleeding in pregnancy increases risks in current/future pregnancies

Vaginal bleeding during the first trimester of a first pregnancy without miscarrying not only increases the risk for complications later in the pregnancy but also in future pregnancies, according to the results of a retrospective, registry-based cohort study conducted in Denmark.

Researchers identified 782,287 women delivering in Denmark from 1978 to 2007 with a first singleton pregnancy and 536,419 first and second singleton pregnancies.

They found that first-trimester bleeding increased the risk for delivery during weeks 32 to 36 from 3.6% to 6.1% (odds ratio [OR], 1.65; 95% confidence interval [CI], 1.57-1.77) and almost tripled the likelihood of delivery during weeks 28 to 31, from 0.3% to 0.9% (OR, 2.98; 95% CI, 2.50-3.54). It also raised the risk for placental abruption by more than 40%, from 1.0% to 1.4% (OR 1.48; 95% CI, 1.30-1.68).

Lykke JA, Dideriksen KL, Lidegaard O, Langhoff-Roos J. First-trimester vaginal bleeding and complications later in pregnancy. Obstet Gynecol. 2010;115(5):935-944.