WASHINGTON (AP) – The Trump administration has published new visa rules aimed at restricting a practice known as “birth tourism.” That refers to cases when women travel to the United States to give birth so their children can have U.S. citizenship.

The rules printed in the Federal Register on Thursday say applicants will be denied tourist visas if they’re determined by consular officers to be traveling to the U.S. primarily to give birth.

It’s a bigger hurdle to overcome, proving they’re traveling to the U.S. because they have a medical need and not just because they want to give birth in the country.

Critics say the new policy could put pregnant women at risk.