heavier than in the past challenge them to meet the previous guidelines (IOM, 1990) and will continue to make it difficult for women to meet the new guidelines for GWG. For example, as discussed in Chapter 2, one trend of concern is the increase in consumption of foods with low nutrient density; this has special implications for pregnancy and lactation, which require modest increases in energy but greater increases in vitamin and mineral intake. Also as discussed in Chapter 2, national data indicate that a high proportion of women of childbearing age fail to meet current guidelines for physical activity. Improvement in both of these statistics could contribute toward helping women enter pregnancy at a healthy weight as well as to meet the proposed guidelines for GWG.

These new guidelines should also be considered in the context of data on women’s reported GWG, which the committee assembled from a series of studies with relatively large samples of women (Table 8-1). As shown in Table 8-1, the mean gains of underweight women are within the new guidelines. This is less often the case for normal weight women, where the mean gain in some samples is at or above the upper limit of the new guidelines. This indicates that a substantial proportion of normal weight women would exceed desired GWG ranges according to the new guidelines. The mean GWG values for overweight and obese women exceed the upper end of the new guidelines by several kilograms. Even when this analysis is restricted to the most recent (2002-2003) multi-state data from Pregnancy Risk Assessment Monitoring System (PRAMS), the same conclusions hold (Figure 8-1). These data provide a strong reason to assume that interventions will be needed to assist women, particularly those who are overweight or obese at the time of conception, in meeting the new GWG guidelines.

The review of interventions that have been conducted based on Nutrition During Pregnancy (IOM, 1990) (see below) provide a preview of the challenges that will be faced in implementing the new guidelines in this report. Although the committee recognizes that developing graphical representations to assist caregivers and their clients in conveying the importance of appropriate weight gain during pregnancy is important, the type of expertise represented on the committee as well as the commitment of time and resources limited the extent to which it could develop such material into a format that could be readily disseminated.

Although data from observational studies have been consistent in showing an association between gaining within the IOM (1990) guidelines and having a lower risk of adverse outcomes (Carmichael et al., 1997; Abrams et al., 2000; Langford et al., 2008; Olson, 2008), this does not mean that women who gain outside the guidelines will have a bad outcome (Parker and Abrams, 1992). This is because many factors other than GWG are related to the short- and long-term outcomes of pregnancy. Nonetheless, monitoring GWG is useful for identifying women who might benefit from