The abortion rate continues to drop, and according to a new report, the main driver is not abortion restrictions.

"We know the use of contraception has gone up, that fact we can be sure of, so I'm sure there's a connection between easy and rapid access to contraception and declining abortions," said medical ethicist Art Caplan.

The report points to a decline in births and pregnancies overall.

"One possible contributing factor is contraceptive access and use," according to the report. "Since 2011, contraception has become more accessible, as most private health insurance plans are now required by the Affordable Care Act to cover contraceptives."

The Guttmacher Institute, which conducted the research, estimated the abortion rate, which is defined as the number of abortions per 1,000 women between the ages of 15 and 44, dropped to 13.5 in 2017 from 16.9 in 2011. That's the lowest rate since abortion became legal nationwide in 1973.

Caplan noted the leading states in declining abortion rates were California and New York, two states with the least abortion restrictions.

"The lesson is the availability of contraception and sex ed are key," said Caplan.

Art Caplan is the Drs. William F. and Virigina Connolly Mitty Chair, and director of the Division of Medical Ethics at NYU Langone Medical Center. He's also host of the Everyday Ethics podcast.