Updated: Sept. 18, 10:26 a.m. ET

The U.S. abortion rate is continuing a long-term downward trend, according to new data released by the Guttmacher Institute on Wednesday.

Guttmacher, which supports abortion rights, finds that the overall number of abortions dropped 7% — to 862,320 in 2017, down from 926,200 in 2014, the last time the data were updated.

In 2017, the abortion rate — which measures how common abortion is among women of childbearing age — dropped to 13.5 abortions per 1,000 women ages 15 to 44, down from 14.6 in 2014. That continues a downward trend since the peak in 1980 of 29.3.

Elizabeth Nash, senior state issues manager at Guttmacher, said the overall drop is not attributable to a growing number of abortion restrictions.

"I don't think there's a clear pattern around why rates are falling," Nash said. "They're going down across the country in nearly every state."

Nash said there are exceptions, notably Texas, where laws and regulations have led to clinic closures and abortion rates have declined as a result. In other states, such as Ohio, Nash said the data suggest restrictions and clinic closures have prompted women to go to neighboring states such as Michigan for the procedure.

Nash notes that the U.S. birthrate is also down, suggesting a decline in the number of women becoming pregnant. Also, the data come from 2017 — before a series of restrictive abortion bans were passed in state legislatures around the country. Those bans have yet to take effect, and many are tied up in legal challenges.

Nash also points to increased use of highly effective contraceptive methods such as IUDs in recent years as one possible cause.

In the past, groups opposed to abortion rights have suggested that the decline is due to changing attitudes about abortion. But public opinion polling suggests that U.S. opinions on abortion rights tend to be largely stable over time.

The report noted a 25% increase in the use of medication abortion, with nearly 4 in 10 abortions in 2017 being performed using abortion pills instead of surgery.

The analysis also includes data suggesting an increase in women using pills or other methods to self-induce abortions without a medical provider's assistance; 18% of non-hospital facilities surveyed said they'd treated at least one patient for an attempted self-induced abortion — up from 12% in the last survey, according to Guttmacher.

In response, Chuck Donovan of the anti-abortion rights group the Charlotte Lozier Institute issued a statement saying in part, "We welcome the new report showing the decline in both the abortion rate and the overall number of abortions from 2011 to 2017." He attributed the decline to factors including limits on public funding for abortion.

Donovan added the increase in medication abortion "should concern us all," calling that news "deeply disturbing."

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