veloped from published and commissioned research data needed to support a more complete and persuasive analysis were unavailable. In particular, more information is needed on associations between GWG and longer term maternal outcomes, such as postpartum weight retention and later reproductive function and health, and child health outcomes such as fetal growth restriction, child neurocognitive outcomes, and obesity. Such data should include not only the frequencies of outcomes but also the utilities associated with each so that appropriate quality adjustments could be calculated.

Overall, these guidelines are remarkably similar to those included in the IOM (1990) report. The research that has appeared since that publication as well as the committee’s commissioned analyses support the robustness of the prior recommendations. Specifically, it remains true that, within a given prepregnancy BMI category, healthy women can deliver healthy infants at a relatively wide range of weight gain values. Unfortunately, an already large and increasing proportion of the population is gaining outside of the prior recommendations (see Chapter 2), which is likely to also be the case with these new guidelines. As a result, it is time to focus attention on helping women to adhere to these guidelines. If research on adherence is conducted with experimental designs of adequate statistical power, such studies could finally provide causal evidence that gaining within these new guidelines results in superior outcomes of pregnancy for both mother and infant.

FINDINGS AND RECOMMENDATIONS FROM THE COMMITTEE’S ANALYSES

Findings

The committee found that:

  1. The WHO cutoff points have been widely adopted for categorizing BMI among nonpregnant adults and should be used for categorizing prepregnancy BMI as well; the committee found that these categories are also acceptable to use for categorizing the prepregnancy BMI of adolescents.

  2. Evidence from the scientific literature is remarkably clear that prepregnant BMI is an independent predictor of many adverse outcomes of pregnancy. As a result, women should enter pregnancy with a BMI in the normal weight category.

  3. Although a record-high number of American women of childbearing age have BMI values in obesity classes II and III, available evidence is insufficient to develop more specific recommendations for GWG among these women.

  4. There are only limited data available to link GWG to health



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