In the late 1990s, scientists studying children's health pondered crucial questions they couldn’t answer: Conditions as diverse as asthma and autism were increasing in prevalence, with no clear reason why. Many suspected that a child’s early environment—even exposures in the womb—were connected to medical problems that manifested years later. For example, is risk of asthma influenced by the stress a mother experiences during pregnancy? What role does air pollution play? What about diet? Those links proved difficult to study because by the time a child shows signs of asthma, it's too late to take a blood sample during pregnancy, or analyze the air the newborn breathed.
To address those challenges, leading pediatric researchers in the U.S. envisioned an ambitious study. They wanted to track 100,000 American children from before birth until the age of 21 by collecting detailed data, biological specimens such as blood and urine, and environmental samples, including dust from childhood homes. In 2000, Congress authorized the National Institutes of Health (NIH) to go ahead with the project, which would be called the National Children's Study.