Association Between Gestational Weight Gain According to Body Mass Index and Postpartum Weight in a Large Cohort of Danish Women

Our aim was to investigate the association between gestational weight gain (GWG) and postpartum weight retention (PWR) in
pre-pregnancy underweight, normal weight, overweight or obese women, with emphasis on the American Institute of Medicine (IOM)
recommendations. We performed secondary analyses on data based on questionnaires from 1,898 women from the “Smoke-free Newborn
Study” conducted 1996–1999 at Hvidovre Hospital, Denmark. Relationship between GWG and PWR was examined according to BMI as
a continuous variable and in four groups. Association between PWR and GWG according to IOM recommendations was tested by linear
regression analysis and the association between PWR ≥ 5 kg (11 lbs) and GWG by logistic regression analysis. Mean GWG and
mean PWR were constant for all BMI units until 26–27 kg/m². After this cut-off mean GWG and mean PWR decreased with increasing BMI. Nearly 40% of normal weight, 60% of overweight and
50% of obese women gained more than recommended during pregnancy. For normal weight and overweight women with GWG above recommendations
the OR of gaining ≥ 5 kg (11 lbs) 1-year postpartum was 2.8 (95% CI 2.0–4.0) and 2.8 (95% CI 1.3–6.2, respectively) compared
to women with GWG within recommendations. GWG above IOM recommendations significantly increases normal weight, overweight
and obese women’s risk of retaining weight 1 year after delivery. Health personnel face a challenge in prenatal counseling
as 40–60% of these women gain more weight than recommended for their BMI. As GWG is potentially modifiable, our study should
be followed by intervention studies focusing on GW.