to be associated with one or more outcomes. The chapter then reviews categories of exposure measures in more detail.


For each priority outcome area, the discussion summarily describes the proposed hypotheses regarding specific outcomes and associated environmental factors as presented in the NCS research plan. It then offers the panel’s assessment in terms of public health significance and soundness of concepts and methodology. Each area ends with one or more recommendations.

Pregnancy Outcomes (1)


The specific pregnancy outcomes identified in the NCS research plan are birth defects, prematurity, outcomes of artificial reproductive technology (ART), and outcomes of pregnancy when the woman has subclinical hypothyroidism (NCS Research Plan, Vol. 2, App. A-2, Pregnancy Outcomes). The NCS proposes to focus on altered maternal glucose metabolism and folate and vitamin supplementation as risk (or protective) factors for birth defects; the role of inflammation in the pathogenesis of prematurity; the association of ART with fetal growth restriction, prematurity, and developmental disabilities; and the relationship between maternal subclinical hypothyroidism and developmental disabilities.

Assessment: Public Health Significance

The outcomes of pregnancy clearly represent an important area for research to which the NCS could make significant contributions. If the outcomes proposed for the NCS, birth defects, prematurity, and the outcomes of ART (and subfecundity generally) are certainly of public health significance. Taken together, they account for up to 15 percent of all pregnancies. Moreover, prematurity and birth defects have proven difficult to predict and prevent (Centers for Disease Control and Prevention, 2007; Institute of Medicine, 2006). Although ART is responsible for a relatively small percentage of births (1-5 percent), it nevertheless contributes significantly to poorer birth outcomes in the United States. Thus, a strength of this section of the NCS research plan is its focus on significant public health problems.

The public health significance of maternal subclinical hypothyroidism is less clear. Limited studies suggest that unrecognized hypothyroidism during

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