JACKSON, Miss. (AP) — Mississippi’s governor has signed the nation’s tightest abortion restrictions into law.

Republican Gov. Phil Bryant signed House Bill 1510 on Monday afternoon. It becomes law immediately and bans most abortions after 15 weeks’ gestation. Bryant has frequently said he wants Mississippi to be the “safest place in America for an unborn child.”

The law’s only exceptions are if a fetus has health problems making it “incompatible with life” outside of the womb at full term, or if a pregnant woman’s life or a “major bodily function” is threatened by pregnancy. Pregnancies resulting from rape and incest aren’t exempted.

Abortion rights advocates are calling the law unconstitutional because it limits abortion before fetuses can live outside the womb. The owner of Mississippi’s only abortion clinic opposes the law and has pledged to sue.