A retrospective study of gestational weight gain in relation to the Institute of Medicine’s recommendations by maternal body mass index in rural Pennsylvania from 2006 to 2015

Michael L. Power, Melisa L. Lott, A. Dhanya Mackeen, Jessica DiBari, Jay Schulkin

In 2009, the Institute of Medicine (IOM) published guidance on gestational weight gain (GWG) modified by maternal pre-pregnancy body mass index (BMI). Estimates indicate that less than half of US pregnant women have GWG within recommendations. This study examined GWG from before (2006-2009) and after (2010-2015) the release of the IOM guidance in a rural, non-Hispanic white population to assess the proportion of women with GWG outside of IOM guidance, whether GWG became more likely to be within IOM guidance after 2010, and identify potential maternal factors associated with GWG outside of recommendations. We examined GWG in 18,217 term singleton births between 2006 and 2015 in which maternal pre-pregnancy BMI could be calculated from electronic medical records at Geisinger, PA, and a subset of 12,912 births in which weekly GWG in the third trimester could be calculated. The primary outcome was whether GWG was below, within, or above recommendations based on maternal BMI. The relationships between GWG, maternal BMI, parity, age at conception, gestation length, and maternal blood pressure were examined. GWG declined with increasing maternal BMI, however, more than 50% of overweight and obese women gained above IOM recommendations. About one of five women gained below recommendations (21.3%) with underweight women the most likely to gain below recommendations (33.0%). The proportion of births with usable data increased after 2010, driven by a higher probability of recording maternal weight. However, the proportion of women who gained below, within or above recommendations did not change over the ten years. GWG above recommendations was associated with higher maternal BMI, lower parity, and longer gestation. GWG below recommendations was associated with lower maternal BMI, higher parity, shorter gestation, and younger age at conception. Maternal blood pressure was higher for GWG outside recommendations. Despite the publication of IOM recommendations in 2009 and an apparent increase in tracking maternal weight after 2010, GWG in this population did not change between 2006 and 2015. A majority of overweight and obese women gained above recommendations. GWG below recommendations continues to occur, and is prevalent among underweight women.