Environmental contaminants and adverse birth outcomes: Synthesizing the science and assessing the trends

Tracking the incidence or prevalence of environmentally-mediated childhood diseases is recognized as a critical need, particularly as unexplained increases in several important diseases are being observed. Data suggest there are increasing trends in adverse birth outcomes, such as preterm delivery (delivery prior to 37 weeks) and low birthweight (birthweight < 2,500 grams). While some portion of this increase may be explained by changes in demographics, such as increases in multiple birth infants, other factors, such as exposure to environmental contaminants may also be playing a role. Evaluating trends over time of birth outcomes which are most likely to have an environmental component helps identify future areas for policy interventions. This presentation will review the epidemiologic literature on environmental contaminants and adverse birth outcomes, present metrics and trends of birth outcomes that are most likely to reflect an environmental component. Tracking low birth weight combines both etiologies related to premature birth (as premature births weight less) and births that result from intrauterine growth retardation. Temporal trends for two metrics for adverse birth outcomes which are least likely to be influenced by multiple birth and most likely to be influenced by environmental factors will be presented. The first is term, singleton births that weigh less than 2,500 grams, the second is singleton births that occur prior to 37 weeks. In addition, results of the trends by race will be presented and other types of metrics for consideration, such as sex ration, will be discussed.