In 1999-2002 the Project Viva team recruited 2,670 pregnant women during their first trimester of pregnancy from eight obstetric (OB) offices of a multi-site group practice in eastern Massachusetts. 2,128 of the women had a live birth and approximately 1,600 mother-child pairs are still involved in the study. Project Viva collects data annually from multiple sources, including questionnaires, interviews, medical records, examinations, and biospecimen samples. Project Viva intends to follow participants as long as there is grant funding and interest from the participants. Some of the most beneficial health findings come from long-term follow-up.