THE NATIONAL CHILDRENʼS STUDY: BEGINNING THE IMPLEMENTATION OF A NATIONAL-PROBABILITY SAMPLE

Abstract

ISEE-251 Introduction: The National Children's Study (NCS) is a longitudinal cohort study that will follow a sample of approximately 100,000 children born in the United States from before birth until 21 years of age. The NCS will investigate the separate and combined effects of environmental exposures (chemical, biological, physical, psychosocial) as well as gene-environment interactions on pregnancy outcomes, child health and development, and precursors of adult disease. Methods: The NCS will employ a national probability sampling approach to select the study population. Approximately 100 US counties were selected as NCS primary sampling units. Up to 5 locations, along with a Coordinating Center, will be chosen as initial “Vanguard” sites and begin NCS implementation in 2005. Because the focus of the study includes assessment of the impact of exposures occurring very early in pregnancy, women of childbearing age, and pregnant women and their partners, are the initial target population for enrollment. Women planning pregnancy will be visited up to four times in the 6 months following enrollment to assess pregnancy status, exposures, and to collect biological specimens. A minimum of 15 in-person study visits are planned from the first trimester of pregnancy through 21 years of age, including both home and clinical visits. Environmental samples will be collected at each home visit as well as from daycare and school settings. Additionally, remote data collections, e.g. telephone, computer, or mail-in questionnaires, will occur approximately every 3 months through age 5 years and yearly thereafter. Discussion: The focus on exposures prior to and early in pregnancy is a unique feature of this study, as is the breadth of planned exposure and outcome measurements.