Iowa legislators passed a so-called heartbeat bill Wednesday that bans abortion after a fetus' heartbeat can be heard through an ultrasound — on average around six weeks into a pregnancy. If signed, it will be the most restrictive abortion law in the country.

The bill was fast-tracked by the Republican-controlled Statehouse and passed in the early hours of Wednesday morning. It now heads to the desk of Gov. Kim Reynolds, who opposes abortion rights but has not made any public comment on whether she will sign the bill.

"Governor Reynolds is solidly pro-life and will never stop fighting to protect the unborn, however, she doesn’t comment on any bill until seeing it in its final form," Reynolds' communications director Brenna Smith told BuzzFeed News in an email Wednesday. "Our office has not yet received the bill from the legislature for review, but the governor looks forward to reviewing the final language with her team and taking action in the next couple of days."

Opponents of the bill argue that it is essentially a complete ban on abortion, as many women do not know they are pregnant until they have missed two periods — about 8 weeks into pregnancy. For women who find out, a recent decline in the number of abortion clinics in the state often makes abortions difficult to obtain in a short period of time.

In recent years, state legislators across the country pushed similar bills banning abortions after six weeks and citing a fetus’ heartbeat as a standard, but none have been signed into law. A similar bill was passed in Ohio in 2016 but was vetoed by Republican Gov. John Kasich. Rep. Steve King, a vehemently anti-abortion Republican from Iowa, introduced similar legislation in Congress last year, but it was shirked in favor of a less restrictive abortion bill.

“The Iowa General Assembly just passed Heartbeat legislation that will protect nearly every baby from abortionists,” King tweeted Wednesday morning. “The most consequential legislation in Iowa history. America thanks you!”