Agencies in 18 states are reporting a steep decline in the rolls for WIC, a nutrition program that targets pregnant women and children, according to a report from Politico.

The WIC program serves about 50 percent of babies born in the U.S., providing vouchers to help pregnant women and parents to buy food and infant formula.

Politico reports that health providers have fielded calls from immigrant families asking to be removed from WIC.

The decline follows news reports about Trump administration plans to deny visa renewals or green cards for immigrants who have used public benefits.

According to documents leaked earlier this year, the Department of Homeland Security planned to broaden the government's definition of benefits to include earned-income tax credits as well as health insurance subsidies and WIC.

The Migration Policy Institute estimated that the number of non-citizens who could be deemed a "public charge" under the proposed rule would increase from 3 percent to 47 percent nationally.

The drop in WIC use is up to 20 percent in some states, though not all of that drop is linked directly to fears about a possible crackdown.

Kathleen Campbell Walker, an immigration attorney at Dickinson Wright in El Paso, Texas, called the policy a "stealth regulation" that is "being applied subliminally" in an interview with Politico. Health advocates say declining use of WIC puts more babies who are U.S.-born citizens at risk of low birth weight and other issues.

Aside from the public health risks, those effects can drive up health care costs that are passed to taxpayers.

Read More:

Immigrants, Fearing Trump Crackdown, Drop Out Of Nutrition Programs (Politico)

Trump Has Scared Immigrants Into Forfeiting Their Kids' Nutritional Benefits (New York Magazine)

As Trump Considers Penalties, Seattle-Area Immigrants Turn Down Public Benefits They're Entitled To Claim (Seattle Times)