The State Department is implementing new rules that would make it more difficult for pregnant foreigners to visit the U.S. as part of an attempt to crack down on "birth tourism."

The new rules, which take effect on Friday, direct consular officers in foreign embassies to deny tourist visas to any pregnant women they think may be visiting the U.S. to give birth. It will be up to the woman to convince the officers that she is there for reasons other than giving birth.

Almost all babies born in the U.S. are granted U.S. citizenship, per the U.S. Constitution.

"This rule reflects a better policy, as birth tourism poses risks to national security," the new rule states.

Around 10,000 babies were born in the U.S. to parents who are foreign citizens in 2017, the last year for which data was available, according to the Centers for Disease Control and Prevention. That number is up from around 7,800 in 2007.