“Why is it,” asked Raymond J. Lavoie, executive director of Blackstone Valley Community Health Care, “that some children develop such diseases as asthma, autism and diabetes, while others grow up healthy?”

The question concerns the community health center, whose 60,000 patients include many children, Lavoie said Monday, addressing a meeting at his health center, a gathering held to publicize a huge study intended to find some answers.

The National Children’s Study will examine diet, chemical exposure and other aspects of daily life of 100,000 children from before birth through age 21. Some 1,000 participants will come from 16 neighborhoods in Providence County, including two neighborhoods in Pawtucket.

“It is the largest, most ambitious, most thorough, most comprehensive study of children’s health that will ever have been undertaken in the world,” said Dr. Stephen L. Buka of Brown University, the study’s principal investigator.

Approaching women when they seek prenatal care, Buka’s team has so far recruited 35 women who are pregnant or may become pregnant and who are willing to answer questions, visit clinics and provide biological samples for years to come. Three babies have already been born into the study.

Sponsored by the National Institutes of Health, the study is still in its pilot phase, with 30 locations testing three methods of recruiting. The Providence County branch of the study, run jointly by Brown and Women & Infants Hospital, is recruiting patients in doctors’ offices.

The study has already started working with about half the prenatal-care providers in the targeted areas, and plans eventually to connect with all. Also, starting next year, the researchers will go door to door looking for participants.

Buka said that the Rhode Island recruitment effort was going better than the others, which have each recruited only about 3 to 10 women. “Pawtucket and all of Rhode Island is already famous for what we can do with this study,” Buka said.