Risk factors of preterm birth in France in 2010 and changes since 1995: Results from the French National Perinatal Surveys

Summary Objectives To investigate risk factors of total, spontaneous and induced preterm birth in 2010 and differences between 1995 and 2010. Material and methods The national perinatal surveys are based on a representative sample of births in France. We selected live-born singletons ( n  = 14,326 in 2010 and 12,885 in 1995) and used multiple regression analyses to calculate adjusted odds ratios (aOR) for maternal sociodemographic characteristics, obstetric history, prenatal care and smoking. Results The main risk factors in 2010 were parity 1 compared to parity 2 (aOR = 1.9 [95% CI 1.5–1.3]), previous preterm delivery (aOR = 6.6 [5.0–8.7]), pre-pregnancy body mass index  2 (aOR = 1.7 [1.4–2.2]), level of education completed: high school or less, inadequate prenatal care and cannabis use. Most risk factors of spontaneous and induced preterm births were similar. Compared to 1995, maternal age ≥ 35 years and previous induced abortion were no longer associated with preterm birth in 2010. Conclusion Identified risk factors for preterm birth in France in 2010 agree with the literature. Increases in baseline rates for maternal age and medically induced abortions may explain changes in certain preterm birth risk factors.