Large-for-gestational-age fetuses have an increased risk for spontaneous preterm birth

Objective: Our aim was to investigate the association between large-for-gestational-age and the risk of spontaneous preterm birth. Study Design: We studied nulliparous women with a singleton gestation using data from the Dutch perinatal registry from 1999 to 2010. Neonates were categorized according to the Hadlock fetal weight standard, into 10th to 90th percentile, 90th to 97th percentile, or above 97th percentile. Outcomes were preterm birth <37 +0 weeks and preterm birth between 25 +0 –27 +6 weeks, 28 +0 –30 +6 weeks, 31 +0 –33 +6 weeks, and 34 +0 –36 +6 weeks. Results: We included 547,418 women. The number of spontaneous preterm births <37 weeks was significantly increased in the large-for-gestational-age group (> p97) compared with fetuses with a normal growth (p10–p90) (11.3% vs. 7.3%, odds ratio (OR) 1.8; 95% CI 1.7–1.9). The same results were found when limiting analyses to women with certain pregnancy duration (after in vitro fertilization). Conclusion: Large-for-gestational-age increases the risk of spontaneous preterm delivery from 25 weeks of gestation onwards.