First-trimester vaginal bleeding and complications later in pregnancy.

Objective: To evaluate the association of first-trimester bleeding without miscarriage and complications later in the first pregnancy as well as in the next pregnancy.

Methods: In a retrospective, registry-based cohort study, we identified women delivering in Denmark from 1978 to 2007 with a first singleton pregnancy (n=782,287) and first and second singleton pregnancies (n=536,419). First-trimester bleeding is defined as vaginal bleeding before 12 full weeks of gestation.