The federal government is looking for 100,000 pregnant women to take part in the National Children's Study.
Scientists will then monitor the babies until they turn 21.
This is the largest long-term study of children's health yet and is projected to cost upwards of $6.5 billion.
Authorized by congress in 2000, the study will examine how environment, genes, and other factors affect children's health.
http://www.nationalchildrensstudy.gov/Pages/default.aspx
