We're moving! Get our latest gender and identity coverage on washingtonpost.com.

The U.S. abortion rate hit an all-time low — again.

A new Guttmacher Institute report released on Wednesday outlines dramatic changes in the abortion landscape between 2011 and 2017. An unprecedented wave of 400 bills imposing restrictions on the procedure were passed by states. And medical abortions, which involve taking pills instead of undergoing a surgical procedure, became widely available.

The 48-page research document from Guttmacher, which is used by policymakers and activists on both sides of the debate, provides detailed information by state and region about how American women access abortion.

There appears to be no clear pattern between efforts to ban or restrict abortion and the continuing decline in abortion rates, which has been going on for nearly 40 years. The declines were seen across regions and in states that are more supportive of abortion rights as well as those that are more restrictive.

“Antiabortion activists are going to try to take credit for this decline, but the facts don’t support their argument,” Rachel Jones, principal research scientist for Guttmacher, which supports abortion rights, said in a call with reporters.

A breakdown of the number

The report estimated the abortion rate in 2017, the most recent year studied, at 13.5 per 1,000 women ages 15 to 44. That compares with 14.6 in 2014 and 16.9 in 2011 and is the lowest rate since the U.S. Supreme Court legalized abortion through the landmark decision Roe v. Wade in 1973.

In total, 862,320 abortions took place in 2017 at health-care facilities. About 339,640, or about 39 percent, of those were medical abortions, which involve taking pills to induce miscarriage as opposed to traditional surgical abortion.

Guttmacher said it was impossible to pinpoint exactly what factors are driving the declines but said there has been a decline in pregnancies as well as “changes around abortion attitudes and stigma, contraceptive use, sexual activity, infertility and self-managed abortion.” Self-managed abortions are those that occur outside of health-care settings and might include the use of medication, herbs or other methods without the direct supervision of a medical professional.

Guttmacher noted that 32 states enacted restrictions during that time period, such as waiting periods, parental consent for minors, and requirements that patients do ultrasounds first. But nearly every state had lower abortion rates regardless of whether the state had passed any laws related to abortion access. And some states with new restrictions saw their abortion rates go up.

Tracking abortion restrictions

Guttmacher logged nearly 400 abortion restrictions passed by states from 2011 to 2017. Indiana — Vice President Pence’s home state and the one in which he served as governor for four of those years — enacted the most, 37. Kansas was close behind with 31, and Arkansas with 29.

Many of the new restrictions have never gone into effect or gone into effect temporarily due to court action. In April of this year, for example, the Kansas Supreme Court blocked a law that banned the most common procedure for second-trimester abortions. It was the first state to try to stop this technique. And in July, a federal judge in Arkansas temporarily blocked three new abortion restrictions including one that requires a physician performing an abortion to be board-certified, which would have likely resulted in the state’s only clinic having to close.

The U.S. Supreme Court in May went in the other direction, upholding part of a law signed by Pence that requires fetal remains of an abortion to be buried or cremated.

Like many health-care studies, the data is a few years behind and does not include the impact of this year’s unprecedented state efforts to ban abortion at six weeks — even in some cases without exception for rape and incest. The 2017 information also predates many efforts by President Trump’s administration, such as the changes to the Title X family planning program that prompted Planned Parenthood to refuse millions of dollars of funding from that source.

The Guttmacher report also provides a glimpse at how deep the divide has grown between states. Between 2011 and 2017, the number of clinics went up in the Northeast and West but declined in the Midwest and South.

While every state in the United States is home to an abortion clinic, five — North Dakota, Kentucky, Mississippi, West Virginia and Kansas — have only one. In contrast, California has 161, the most in the nation; New York, 113; Florida, 65; and New Jersey, 41.

The change in abortion rates shows dramatic state-by-state variation. In Virginia, it fell 41.5 percent, for example, while it went up slightly in New Jersey and Washington, D.C.

Guttmacher officials emphasized that while restrictions may not be impacting the overall numbers, they take a toll on individuals.

“Abortion restrictions are coercive and cruel by design and intended to impose a heavy financial and emotional toll,” said Herminia Palacio, Guttmacher president and CEO.

What happens to Roe v. Wade without Ruth Bader Ginsburg?

Justice Ruth Bader Ginsburg died on Friday at age 87

Biden took credit for putting RBG, Kagan and Sotomayor on the Supreme Court. But he left out Clarence Thomas.

It struck many viewers as tone-deaf

The Supreme Court will review the ruling on a restrictive Louisiana abortion law

Clinic owners said the effect of the law would be to close most of the state’s abortion clinics, leaving only one doctor eligible to perform the procedure