Factors associated with preterm delivery in women with type 1 diabetes: a cohort study.

OBJECTIVE The reported rate of preterm delivery in women with type 1 diabetes ranges from 22 to 45%, but the reasons are unclear. The purpose of this study was to identify factors associated with preterm delivery in these women. RESEARCH DESIGN AND METHODS We studied the influence of maternal and diabetes-related factors on the occurrence of preterm delivery in 168 single pregnancies occurring in 127 women with type 1 diabetes. Women with spontaneous or indicated preterm delivery were compared with those who delivered after 37 weeks of gestation using polytomous logistic regression. RESULTS The overall rate of preterm delivery was 24%, fivefold higher than the French prematurity rate in single pregnancy. Preterm delivery was spontaneous in 9% and indicated in 15%. HbA1c > or =7% at delivery was associated with spontaneous preterm delivery (odds ratio [OR] 5.3 [95% CI 1.1-26.8]). Nulliparity (12.0 [2.3-64.1]), progression of nephropathy (7.7 [1.3-46.9]), preeclampsia (12.0 [3.1-47.1]), and HbA1c > or =7% (7.5 [1.5-37.9]) at delivery were all associated with indicated preterm delivery. Preterm delivery was associated with significant neonatal morbidity as the risks for neonatal hypoglycemia and respiratory distress syndrome were increased by three- to sixfold compared with the reference group. CONCLUSIONS The rate of preterm delivery remains high in women with type 1 diabetes. Different factors were associated with spontaneous and indicated preterm delivery, respectively. Because poor glycemic control was a risk factor for both outcomes, part of preterm delivery might be preventable.