Thanks to the Affordable Care Act (ACA) a record number of American children now have access to health insurance. But getting treatment under the legislation’s government-subsidized plans can be difficult, according to a recent study released by the Children’s Health Fund, The New York Times reports.

Specifically, the nonprofit found that 20.3 million people under age 18 in the United States currently lack “access to care that meets modern pediatric standards.” These guidelines, established by the American Academy of Pediatrics, include regular doctor visits for immunizations and other preventive care, management of acute and chronic illnesses, access to mental health support and dental care, and around-the-clock availability of emergency services.

Although Medicaid and many private insurance plans require that these medical services be provided, the Children’s Health Fund study found that millions of youngsters with coverage don’t receive these benefits. Researchers compiled the information from census data and reports by federal agencies, such as the Centers for Disease Control and Prevention, as well as a national network of nonprofits that provide health care to underserved children across the country.

In addition, findings showed that securing quality care is often confusing and expensive, even for those with insurance. What’s more, the study estimated that nearly 14 million children live in areas with a shortage of health professionals, defined as an area with less than one primary care doctor for every 3,000 people. The report also found that 59 percent of pediatricians said they had a hard time collecting shares of deductibles and copayments from families with high-deductible health plans.

“The fact that more than 20 million children in the U.S. experience insurance and noninsurance barriers to getting comprehensive and timely health care is a challenge that needs to get the highest-priority attention from the new administration,” said Irwin Redlener, MD, PhD, president of the nonprofit Children’s Health Fund and the report’s lead author.

Researchers said they are worried that even more children could have trouble receiving the care they need since President-elect Donald Trump has vowed to repeal some, if not all, of the ACA during his upcoming presidency.

Click here to learn more about finding affordable health care under current U.S. insurance guidelines.