The Trump administration is imposing new visa rules aimed at restricting “birth tourism,” in which women travel to the United States to give birth so their children can have U.S. citizenship. The regulations will take effect Friday.

Under the new rules, pregnant applicants will be denied a tourist visa unless they can prove they must come to the U.S. to give birth for medical reasons and they have money to pay for it or have another compelling reason — not just because they want their child to have an American passport.

Officials said the rule will not apply to foreign travellers coming from any of the 39 mainly European and Asian countries enrolled in the Visa Waiver Program, which allows citizens of those countries to come the U.S. without a visa for temporary stays. The rule will only apply to applicants for so-called “B” class visas that permit short-term stays for business or pleasure.

The State Department “does not believe that visiting the United States for the primary purpose of obtaining U.S. citizenship for a child, by giving birth in the United States — an activity commonly referred to as ‘birth tourism’ — is a legitimate activity for pleasure or of a recreational nature,” according to the new rules, which were published Thursday in the Federal Register.