Starting next fall, about 1,000 Hidalgo County children will participate in a large-scale research project following American children from the womb to their 21st birthday.

Hidalgo County is one of 100 counties nationwide that researchers have designated as sites for The National Children’s Study, a longitudinal study of 100,000 children across the country. The study will examine the impact of numerous social and environmental factors — such as diet, pollutants and poverty — on children’s health and development.

The ambitious study will give researchers a much more complete picture of how the environment influences a person from conception to early adulthood, said Dr. Daniel Hale, an investigator in the study and pediatrics professor at the University of Texas Health Science Center at San Antonio. UT Health Science Center researchers will oversee the study in Hidalgo County.

“The goal of the study is to get a handle on all aspects of pregnancy and childhood,” Hale said. “That includes biological, physical, chemical and social factors.”

Authorized by the federal Children’s Health Act of 2000, the study is the progeny of the National Institute of Child Health and Human Development, along with several other federal agencies. Research first began in 2005 at seven sites throughout the U.S., and officials announced last week the addition of 22 more sites, including San Antonio’s Bexar County.

Hidalgo County likely will be included in the next round of site choices, which should be announced next year, Hale said. The study later will include Dallas, Travis, Harris and Lamar counties.

The project is unique for several reasons, officials say: it follows children from all parts of the country with different backgrounds, it looks at a wide variety of environmental factors and their impact on children’s health, and it follows participants from before birth until they reach adulthood.

“The purpose is to uncover the root cause of the diseases children in the U.S. face today,” said Sarah Keim, deputy director of The National Children’s Study program office.

Hale said that the study will offer a “broader and deeper picture of childhood.”

“I think it will give us the opportunity to explore almost everything that can lead to good and bad health in childhood,” he said. “We’ll be able to look at the impact of ethnicity, birth order, poverty, pesticides and more on pregnancy outcomes, on children … It will help answer a lot of questions we haven’t even begun to think about.”

The investigators will start with randomly selected census tracts in Hidalgo County, recruiting more than 1,000 women from those tracts who are pregnant or who plan to become pregnant in the next year. Researchers plan to enlist the help of promotoras, or community-health workers, hospitals and clinics in the effort, Hale said.

Only two of the 100 proposed sites — Hidalgo and San Diego County in California — are on the U.S.-Mexico border.

Including border counties in the study was necessary to paint a complete portrait of childhood in America, Keim said.

“We wanted to include special populations and geographic diversity,” Keim said.

Completion of the study is contingent on federal funding, Hale said. So far the project has received $124 million, but needs funding for future phases, officials said.