Donald Trump’s election may have inspired a birth control boom.

Intrauterine device (IUD) prescriptions and procedures increased 19 percent between October and December of this year, according to a data set compiled by analysts for the electronic health record AthenaHealth. No similar pattern was observed at the end of 2015.

In the wake of Trump’s surprise electoral victory, social media was replete with anecdotes of women worried about the possible repeal of Obamacare’s birth control mandate — and rushed to the doctor to get IUDs, one of the most effective reversible contraceptives.

“The morning after the election we had an immediate uptick in calls from women who were concerned about the election,” says Gretchen Borchelt, the vice president for reproductive rights and health at the National Women’s Law Center, which manages a birth control hotline. “They didn’t know if they were going to lose coverage, whether they should go out and get an IUD.”

At Vox’s request, AthenaHealth compiled data from 2,500 doctor offices across the country that use its electronic medical record and have provided IUDs over the past 15 months (92 percent of these doctors are OB-GYNs). It then showed us the month-by-month trends in IUD demand.

The data showed an increase from 10,850 IUD-related appointments in October to 12,938 in December. The increase showed up in conservative and liberal areas of the country, although it was steeper in areas that supported Clinton in the 2016 election.

“Our data really complements the anecdotes,” says Josh Gray, vice president at AthenaResearch. “I do think we’re capturing a national trend.”

A separate health data firm, Amino Health, also reported an uptick in IUD insertions in December, although it was a bit more cautious in describing the data.

“Both of our data sets show that there was an increase in December,” Amino data scientist Sohan Murthy said after reviewing both Amino’s and then Athena’s data. “We think it’s too early to tell if this increase was due to post-election interest in IUDs, given season variation over the last three years.”

Why women were seeking IUDs after the election

IUDs are amazingly, fantastically good at preventing pregnancy — better than pretty much any other available contraceptive. Birth control pills have a 6 percent failure rate, meaning that 60 of 1,000 women using them will become pregnant. IUDs, meanwhile, have a failure rate below 1 percent.

After the election, the AthenaHealth data shows a slight uptick in the share of doctor visits about birth control where IUDs were discussed.

There are likely two explanations for that shift. The first is that IUDs last a long time. Once inserted, IUDs prevent pregnancy for between three and 12 years, depending on the specific device. Long enough, in other words, to last through Trump’s entire presidency.

“We have some women who have called our hotline and said, ‘I need birth control that can wait out this administration and get me through the next four years,’” Borchelt says.

The second: Without Obamacare’s birth control mandate, IUDs would be quite expensive. The median cost of a hormonal IUD in the United States ranges from $187 to $736, depending on where you live, according to data from Amino Health. This is significantly more than birth control pills, which exist in generic forms and are available for a much lower price.

The health care law required insurance companies to cover IUDs and other contraceptives at no cost to the consumer. But if the mandate goes away, IUDs could once again become an especially expensive contraceptive.

Borchelt’s group, which runs a hotline on birth control coverage, isn’t urging patients to rush to the doctor immediately. Borchelt says women still have some time to make these decisions — we just don’t know how much.

“What we’re telling women is that you won’t lose the benefit right away, but if you’ve been thinking about long-lasting contraceptives like IUDs, now might be a good time to have that conversation with your doctor,” she says.