Americans who use birth control pills saved $1.4 billion on the cost of their contraception in 2013 after the implementation of the Affordable Care Act, according to a new report published in the policy journal Health Affairs.

In fact, out-of-pocket spending on most reversible contraceptive methods has gone down as of January 2013, and the savings are being passed on directly to families.

Researchers at the University of Pennsylvania analyzed claims data from a nationwide provider of private insurance, and found that on average, contraceptive pill and IUD users spent 20 percent less out-of-pocket on their chosen family planning methods post-ACA.

According to the report:

We estimated average out-of-pocket savings per contraceptive user to be $248 for the intrauterine device and $255 annually for the oral contraceptive pill. Our results suggest that the mandate has led to large reductions in total out-of-pocket spending on contraceptives and that these price changes are likely to be salient for women with private health insurance.

The Affordable Care Act’s contraceptive coverage isn’t “free” birth control—the ACA’s mandate requires insurance companies to provide contraception without additional out-of-pocket costs beyond those already paid through premiums that go toward preventive care, which includes contraception.

Some contraceptive brands are still not required to be covered by the ACA, but researchers found that their sample group—nearly 800,000 women—cut their pill expenses by 50 percent during the first half of 2013, and by 70 percent on intrauterine devices (IUDs).

While researchers did not draw a direct causal relationship between the ACA and out-of-pocket contraception savings, the director of women’s health policy at the Kaiser Family Foundation told the New York Times that the Pennsylvania study was “persuasive and consistent with what other studies are finding,” and that there was a “clear pattern in the research.”

In an attempt to derail the ACA’s contraceptive coverage mandate despite its documented savings potential, some congressional Republicans have begun a push to make some birth control available over the counter, which could increase costs by significantly reducing access to prescription-covered contraception, since insurers are not required to cover over-the-counter drugs.

Democrats have responded by proposing a bill that would close the over-the-counter coverage loophole, requiring insurers to do just that.