Starting tomorrow, consumers can once again shop for coverage through the Health Insurance Marketplace.

What was once considered a ground-breaking U.S. study to track the health of children from birth to adulthood may be stopped before its official start, causing alarm for advocates and researchers who say its findings are crucial to developing prevention strategies for childhood illnesses like asthma, autism and attention deficit disorder.

Researchers for the National Children’s Study, devised by Congress in 2000, say the study could eventually influence a range of parental choices – from what foods kids eat to the household products or medications they are exposed to. Study advocates also say the potential findings are endless, and will likely go beyond advice given to parents, to have an impact on insurance-coverage decisions and even broader public policy questions.

“We don’t have the evidence we need to truly improve children’s health in this country. We need this study. … The importance of the investment is clear,” said Lisa Simpson, president and CEO of AcademyHealth, a membership group of policy analysts and health services researchers, and who was involved in the study’s early years.

The 21-year longitudinal study of 100,000 children was set to start this year. Its implementation, though, has snagged on concerns that it’s based on costly and antiquated research methods, and that it has been plagued by mismanagement. A National Institutes of Health working group is investigating these issues and offering recommendations –due out in December — about the initiative’s future.

Almost ten years before the study’s launch, and amid growing concerns that children suffered disproportionately from the effects of social and environmental factors, President Bill Clinton created a task force to look at policy solutions, which eventually called for legislation to mandate a large study. In May 2000, former Rep. Michael Bilirakis, R-Fla., introduced the act, which was passed and then signed by Clinton that October.

The Vanguard Study, which began in 2007 as the official precursor to the NCS, is a small version of the main study. It has been operating through 40 sites to test ways to recruit women who expect to be pregnant in the near future, and to experiment with data systems. Since then, however, this blueprint has been marked by problems, which led to a July Institute of Medicine report questioning whether the main study should be given a green light to go forward without major changes.

Even researchers involved in the pilot project have criticized it for not identifying a streamlined sampling strategy. The study’s design also fails to take advantage of a number of communications tools, including social media, email, text messages and phone calls.

Jane Holl, a principal investigator who also is a professor of pediatrics and preventive medicine at Northwestern University, expressed frustration that researchers aren’t allowed to use these common-sense ways to keep in touch with participants. Despite this disenchantment, though, the potential findings keep her interested in the project’s potential.

“It could tell us so much about relationships — starting in the prenatal period through late childhood — and how those factors affect early adulthood,” Holl said, who is charged with overseeing ten of the 40 pilot sites.

Federal support for the research is also at risk. Funding was put on hold for the main study in 2013 after congressional appropriators provided $165 million per year for the main study — $30 million less than initially planned, and made that money hinge on the Institutes of Medicine evaluating progress. This reality has added to advocates interest in the NIH working group’s recommendations, and the potential ways that more could be done with less.

Often research is focused on adult illnesses instead of studying children until adulthood and figuring out how to prevent later-in-life health problems, said James Perrin, president of the American Academy of Pediatrics.

“If I’m a member of Congress, I’m more concerned about heart disease at 50-years-old, and that’s where we’ve funded it more actively. We need to know what we can do in childhood,” Perrin said, adding that “we’re impatient at this point” and it’s important to “deal with the logistical problems.”

Kaiser Health News (KHN) is a national health policy news service. It is an editorially independent program of the Henry J. Kaiser Family Foundation.

Millions of low-income children are failing to get the free preventive exams and screenings guaranteed by Medicaid and the Obama administration is not doing enough to fix the problem, according to a federal watchdog report.

The report, released Thursday by the Department of Health and Human Services’ Office of Inspector General (OIG), says the administration has boosted rates of participation but needs to do more to ensure that children get the regular wellness exams, dental checkups and vision and hearing tests. The report notes that 63 percent of children on Medicaid received at least one medical screening in 2013, up from 56 percent in 2006, but still far below the department’s 80 percent goal.

Only Iowa and California exceeded that standard last year. Alaska and Ohio were below 40 percent. Five more states — Mississippi, Montana, North Dakota, Oregon and Wyoming — were between 40 percent and 45 percent.

Child health advocates cite several factors for the low rates, including a shortage of doctors treating Medicaid patients, states’ low pay for providers and parents’ lack of awareness about the importance of the visits.

Both children and taxpayers pay a steep price when children’s health problems are not caught early.

“We end up with kids who are sicker, with more long-term, serious medical issues that are more expensive to treat,” said Jennifer Clarke, executive director of Public Interest Law Center of Philadelphia.

Some experts say that state officials — not the federal government— bear most of the responsibility for low screening rates because they administer Medicaid, the state-federal program for the poor. They say states need to step up oversight over the private Medicaid health plans that many contract with to cover children in the program.

“The federal government is working hard on this, but the only power they have over states is to take away their funding and that is highly unlikely,” said Jane Perkins, legal director of the National Health Law Program.

Congress introduced the Medicaid benefit, known as the Early and Periodic Screening, Diagnosis and Treatment program, or EPSDT, in 1967 so that children would get age-appropriate diagnostic tests, including for vision and hearing, preventive services such as immunizations and treatments. About 32 million children on Medicaid were eligible for the benefit in 2013.

The preventive care program is more generous than those offered by the Children’s Health Insurance Program (CHIP) or private health insurers because it guarantees coverage not just for a wide range of tests, but also the treatments to address health problems. Most states follow the guidelines of the American Academy of Pediatrics, which calls for 13 preventive visits in first three years of life followed by mostly annual visits until age 21.

Boston pediatrician Michael McManus, a member of the academy’s state government affairs committee, said he is saddened by the fact that more than a third of children on Medicaid are not getting at least one regular preventive exam. “We have a lot of work to do,” he said.

Low participation rates have plagued the program for years, according to previous reports by the inspector general’s office and the U.S. Government Accountability Office.

A 2010 OIG report found that 76 percent of children in nine states did not receive all required medical, vision, and hearing screenings, 41 percent of children nationwide did not receive any of the screenings, and more than half did not receive any vision or hearing screenings. All states are required to provide the benefit.

The latest OIG report praised the U.S. Centers for Medicare & Medicaid Services for working to increase screening rates, such as by distributing guides that enable states and providers to share their best ideas. The guides show, for instance, how some states used websites to educate providers and parents. Some states such as New York require Medicaid health plans to educate members about the benefit and what it covers. Neighborhood Health Plan of Rhode Island boosted adolescent screening rates by 40 percent by offering gift certificates for pizza and movie tickets, according to a 2014 CMS report.

Still, the report said, “the underutilization of medical screenings is an ongoing concern.” CMS has done “very little” to encourage providers to complete all five components of an EPSDT medical screening—   physical exam, medical history, immunizations, lab test and education, the report said.

CMS had no immediate comment on the report.

Medical screening rates fall off dramatically as children get older, according to federal data that track states’ efforts. For example, about 90 percent of children below the age of 1 get at least one screening. But screening rates drop to 77 percent for kids between the ages of 1 and 2, and 56 percent for those between 10 and 14.

Ohio, which had the lowest rate of children getting regular exams in 2013, attributed its problems to getting Medicaid managed care plans to report their data to the state.

Neva Kaye, interim executive director of the National Academy for State Health Policy, said data collection is an issue for some states but it doesn’t explain most of the low rates.  In addition to the shortage of doctors participating in Medicaid, parents often face transportation and language barriers getting children in for the exams, she said.

Dr. David Kelley, chief medical officer for Pennsylvania’s Medicaid program, said that state is working to boost the number of children getting checkups in part by paying bonuses to doctors to do them. He said that the rate of Pennsylvania kids getting the screenings is “in the middle of the pack” and “that is not good enough.”

Clarke, with the Public Interest Law Center, said low Medicaid reimbursement to pediatricians means fewer doctors are available to see poor children and parents face long delays getting their kids in for preventive visits and treatment, if they can get to see them at all.

The center filed a federal class-action lawsuit in 2005 against the state of Florida on behalf of 2 million children in Medicaid saying low reimbursement for Medicaid pediatricians prevented children from getting the health services to which they are entitled. A judge is expected to rule later this month on the case.

Kaiser Health News (KHN) is a national health policy news service. It is an editorially independent program of the Henry J. Kaiser Family Foundation.