Short interpregnancy interval raises preterm birth risk

Short pregnancy intervals increase the risk of preterm birth after adjusting for age and other factors, researchers report in the September issue of the American Journal of Obstetrics & Gynecology.

Emily A. DeFranco, DO, of Washington University School of Medicine in St. Louis, and colleagues conducted a retrospective, population-based study of 156,330 women who had two consecutive live births between 1989 and 1997. They compared interpregnancy intervals of less than 6 months, 6 to 12 months, 12 to 18 months, and longer than 18 months.

The researchers found that short intervals were associated with an increased risk of preterm birth after adjusting for sociodemographic factors. Of 15,200 women with intervals of less than 6 months, almost 7% had a preterm birth. This compared with 4.3% among 27,405 women with intervals of 6 to 12 months; 3.3% among 27,523 women with intervals of 12 to 18 months; and 3.1% among 86,202 women with intervals longer than 18 months. Having a previous preterm birth was also found to be a risk factor for recurrence.

DeFranco EA, Stamilio DM, Boslaugh SE, et al. A short interpregnancy interval is a risk factor for preterm birth and its recurrence. Am J Obstet Gynecol. 2007;197:264.e1-264.e6.