To examine the relationship between vaginal bleeding during early pregnancy and preterm delivery. Study subjects (N=2678) provided information regarding socio-demographic, biomedical, and lifestyle characteristics. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI). Any vaginal bleeding in early pregnancy was associated with a 1.57-fold increased risk of preterm delivery (95% CI: 1.16-2.11). Vaginal bleeding was most strongly related with spontaneous preterm labor (OR=2.10) and weakly associated with preterm premature rupture of membrane (OR=1.36) and medically induced preterm delivery (OR=1.32). As compared to women with no bleeding, those who bled during the first and second trimesters had a 6.24-fold increased risk of spontaneous preterm labor; and 2-3-fold increased risk of medically induced preterm delivery and preterm premature rupture of membrane, respectively. Vaginal bleeding, particularly bleeding that persists across the first two trimesters, is associated with an increased risk of preterm delivery.
