Gestational weight gain in obese mothers and associations with fetal growth

Am J Clin Nutr. 2010 Sep;92(3):644-51. doi: 10.3945/ajcn.2010.29726. Epub 2010 Jul 14.


Background: In 2009, the Institute of Medicine recommended gestational weight gains (GWGs) of 5-9 kg for all obese women. Recommendations by severity of obesity were not specified because of a lack of available data.

Objective: Our objective was to examine associations between GWG and fetal growth in obese women and assess interactions with obesity severity.

Design: We used 2004-2006 Pregnancy Nutrition Surveillance System data from 122,327 obese mothers [prepregnant body mass index (BMI; in kg/m(2)) ge 30]. We used logistic regression to estimate measures of fetal growth including small-for-gestational-age, which was defined as birth weight (BW) lt 2 SDs below the sex and race-ethnicity-specific mean BW (SGA(2SD)), and macrosomia (BW ge 4500 g). We tested for interactions between obesity severity (class I: BMI of 30-34.9; class II: BMI of 35.0-39.9; class III: BMI ge 40) and GWG.

Results: Obesity severity modified associations between GWG and fetal growth. Compared with weight gains of 5-9 kg, weight loss in class I women significantly increased the odds of SGA(2SD), whereas a GWG from 0.1 to 4.9 kg was not associated with SGA(2SD) and did not decrease the odds of macrosomia. In class II and III women, compared with weight gains of 5-9 kg, a GWG from minus 4.9 to +4.9 kg was not associated with SGA(2SD) but did decrease the odds of macrosomia.

Conclusions: Our study suggests a GWG below the Institute of Medicine guidelines may be associated with more favorable BW for all obese women, and GWG may need to be further defined by obesity severity.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Birth Weight*
  • Body Mass Index
  • Female
  • Fetal Development*
  • Fetal Macrosomia / epidemiology
  • Humans
  • Infant, Newborn
  • Infant, Small for Gestational Age
  • Logistic Models
  • Male
  • Obesity / classification
  • Obesity / complications*
  • Pregnancy / physiology*
  • Prevalence
  • Risk Factors
  • Severity of Illness Index
  • Weight Gain*
  • Weight Loss
  • Young Adult