Maternal weight gain and preterm delivery.

This study examined the relationship between maternal weight gain and preterm delivery in 2163 women who participated in the Prenatal Nutrition Project at the University of California, San Diego between 1978-1986. Multivariate analysis of the data indicated that the risk of spontaneous preterm birth increased 60% in women with a low rate of weight gain (less than 0.27 kg/week) compared with those with an average rate (0.27-0.52 kg/week). Women with a low rate of gain were more than twice as likely to experience a preterm delivery as those with a high gain (higher than 0.52 kg/week); the odds ratio was 2.54 and 95% confidence interval was 1.49, 4.88. This difference in weight gain appeared after 20 weeks' gestation.