Maternal characteristics associated with gestational weight gain in France: a population-based, nationally representative study.

OBJECTIVES To provide nationally representative estimates of gestational weight gain (GWG) and identify maternal characteristics associated with inadequate GWG in France. DESIGN A population-based study using data from the French National Perinatal Survey: 2010 and 2016. SETTING All maternity units in metropolitan, mainland France (n=535 in 2010; n=493 in 2016). PARTICIPANTS Singleton live births with GWG data (N=24 850). PRIMARY OUTCOME MEASURES GWG was calculated as end of pregnancy minus pre-pregnancy weight (kg) and categorised as 'insufficient', 'adequate', or 'excessive' using 2009 Institute of Medicine thresholds. Classification accounted for pre-pregnancy body mass index (BMI) (kg/m2; underweight (<18.5), normal weight (18.5-24.9), overweight (25-29.9), obese (≥30)) and gestational age at birth. We estimated average GWG and the percentage of women in each GWG category. Polytomous logistic regression identified characteristics associated with GWG adequacy. RESULTS Average GWG was 13.0 kg (SD 5.6), with 26.8% of women gaining insufficiently, 37.0% adequately and 36.1% excessively. Among other factors, insufficient GWG was associated with underweight (vs normal weight; adjusted OR (aOR) 1.4, 95% CI 1.2 to 1.5) and obese (aOR 1.5, 95% CI 1.4 to 1.7) BMI. Excessive GWG was associated with overweight (aOR 2.8, 95% CI 2.6 to 3.1) and obese BMI (aOR 3.3, 95% CI 2.9 to 3.6). Examining obesity classes separately, odds of insufficient GWG increased from obesity class I to III, while odds of excessive GWG decreased from obesity class I to III. Primiparity (insufficient: aOR 0.9, 95% CI 0.9 to 1.0; excessive: aOR 1.2, 95% CI 1.2 to 1.3), maternal characteristics indicative of lower socioeconomic status, and continuing or quitting smoking during pregnancy were also associated with inadequate GWG. CONCLUSIONS In France, insufficient and excessive GWG are common. For optimal outcomes, clinician education, with special attention to the needs of higher risk/vulnerable groups, is needed to ensure all women receive appropriate advice for recommended GWG.