groups, women of short stature, and women carrying twins; and detailed historic trends in weight gain recommendations and guidelines. The IOM (1990) recommendations for weight gain during pregnancy have been adopted by or have been influential in many countries. Observational studies have demonstrated that women who enter pregnancy at a normal BMI and gain within the recommended ranges are more likely to have a good birth outcome than women who gain outside the recommended ranges (Taffel et al., 1993; Abrams et al., 2000; Groth, 2006).
In the years since the release of the weight gain recommendations from the IOM (1990) report, however, some dramatic shifts in the demographic and epidemiologic profile of the U.S. population have occurred. Notably, the population of U.S. women of childbearing age has become more diverse; and prepregnancy BMI and excess GWG have increased across all population groups, particularly among minority groups who are already at risk for poor maternal and child health outcomes (Yeh and Shelton, 2005; Kim et al., 2007). These and other factors suggested a need to consider whether a revision of the IOM (1990) pregnancy weight gain guidelines is necessary.
The IOM (1990) pregnancy weight guidelines were developed principally in response to concerns about low birth weight infants. Although adverse health outcomes for excess weight gain were considered in the IOM (1990) weight gain guidelines, the recommendations were derived largely from data collected in the 1980 National Natality Survey (Available: http://www.cdc.gov/nchs/about/major/nmihs/abnmihs.htm [accessed March 3, 2009]) and focused on preventing premature births and small-for-gestational age infants.
The IOM (1990) report and a subsequent report, Nutrition During Pregnancy and Lactation: An Implementation Guide (IOM, 1992), identified specific actions practitioners could take to achieve the recommendations in working with patients. They also identified a series of recommendations for epidemiologic, basic, and applied research to enable better estimates of GWG, prepregnancy weight for height, and gestational duration, which affect study design and interpretation.
In 1996 an expert work group was convened by the Maternal and Child Health Bureau of the Health Resources and Services Administration