Recurrence of preterm birth in singleton and twin pregnancies

OBJECTIVE: To assess recurrence of preterm birth and its impact on an obste tric population. METHODS: Women with consecutive births at our hospital beginning with their first pregnancy were identified (n = 15,945). The first pregnancy was cate gorized as delivered between 24 and 34 weeks' gestation or 35 weeks or beyo nd, singleton or twin, and spontaneous or induced. The risk of preterm deli very in these same women during subsequent pregnancies was then analyzed. RESULTS: Compared with women who delivered a singleton at or beyond 35 week s' gestation in their first pregnancy, those who delivered a singleton befo re 35 weeks were at a significant increased risk for recurrence (odds ratio [OR] 5.6, 95% confidence interval [CI] 4.5, 7.0), whereas those who delive red twins were not (OR 1.9, 95% CI 0.46, 8.14). The OR for recurrent sponta neous preterm birth presenting with intact membranes was 7.9 (95% CI 5.6,11 .3) compared with 5.5 (95% CI 3.2, 9.4) with ruptured membranes. Of those w omen with a recurrent preterm birth, 49% delivered within 1 week of the ges tational age of their first delivery and 70% delivered within 2 weeks. Amon g 15,863 nulliparous women with singleton births at their first delivery, a history of preterm birth in that pregnancy could predict only 10% of the p reterm. births that ultimately occurred in the entire obstetric population. CONCLUSION: In a population-based study at our hospital, women who initiall y delivered preterm and thus were identified to be at risk for recurrence u ltimately accounted for only 10% of the prematurity problem in the cohort. (C) 2001 by the American College of Obstetricians and Gynecologists.