Associations Between Maternal Body Mass Index, Gestational Weight Gain, Maternal Complications, and Birth Outcome in Singleton, Term Births in a Largely Non-Hispanic White, Rural Population.

In 2009, the Institute of Medicine (IOM) published guidance on gestational weight gain (GWG) modified by body mass index (BMI). GWG outside of IOM recommendations negatively affects birth outcomes and child health. This study examined the relationship between BMI, GWG, birth complications, and birth outcomes in a rural, non-Hispanic white population over 10 years. We examined maternal BMI, GWG, birth weight, birth complications, and Apgar score in 18,217 term singleton births from medical records at Geisinger, PA from 2006 to 2015. Primary outcomes were GWG, delivery mode, Apgar score, and infant birth weight. A majority of women (74.2%) had GWG outside of recommendations. Prevalence of cesarean delivery was highest for women with GWG above recommendations regardless of BMI. One in five neonates of obese women with GWG above recommendations had Apgar scores below eight. Although most births were normal for gestational age (88%), underweight women who gained below recommendations had the highest percentage of small for gestational age (SGA) births (10.4%) and obese women who gained above recommendations had the highest percentage of large for gestational age (LGA) births (22.2%). Among women with BMIs above 35 kg/m and GWG within recommendations, 18.9% of births were LGA. Most pregnant women are not gaining weight within recommendations. GWG outside of IOM recommendations resulted in poorer birth outcomes, particularly in underweight and obese women. Underweight women with GWG below recommendations are at increased risk for SGA neonates. We suggest reducing GWG recommendations for women above 35 kg/m to decrease LGA births and pregnancy complications.