Last week, Georgia state legislators passed another “fetal heartbeat” bill that would severely limit millions of women’s access to abortion across the state.

The bill, which would ban abortion before many women are even aware of their pregnancy, will go into law if Republican Gov. Brian Kemp signs it in the coming months, as he’s indicated he will do.

Here’s what you need to know about why abortion rights groups are hellbent on stopping him.

It would be one of the country’s most extreme abortion laws.

The proposed law would ban abortion as soon as a doctor can detect a fetal heartbeat, which usually happens at around six weeks into a pregnancy. That’s before most women even know they’re pregnant.

Kemp’s signature would override current Georgia law, which allows abortion up until 20 weeks. If he signs it, Georgia will become one of the most restrictive states in the country for women seeking an abortion.

Abortion rights groups have come out hard against the legislation.

“This is an all-out assault on the reproductive health and safety of Georgia women,” said Laura Simmons, director of NARAL Pro-Choice Georgia, in a statement when the legislature passed the bill.

“This cruel, unconstitutional bill is part of an extreme GOP agenda to strip freedoms from women and could not be further from the values that most Georgians hold,” she continued, pointing to recent polling that found 7 out of 10 Georgians believe abortion should be legal and that the government should not prevent a woman from obtaining one.

It’s not rooted in reality.

The bill’s author, Republican Rep. Ed Setzler, said in a Fox News appearance this week that his legislation “recognizes something that’s pretty common sense: that the child with a human heartbeat living inside their mother is worthy of full legal protections.”

But critics argue that its passage would violate the legal protections women gained with 1973′s Roe v. Wade decision, which prevents states from putting an undue burden on women seeking an abortion.

Opponents of so-called heartbeat bills also point out that Setzler’s thinking is flawed because it implies the fetus would be able to survive on its own outside the womb.

Picking the detection of a heartbeat as a firm cutoff date is “by all accounts an arbitrary standard that bans abortion long before the point of fetal viability,” Planned Parenthood of the Heartland spokeswoman Becca Lee said last year when the Iowa Legislature passed a similar bill.