Take-at-home abortion medications are not included in new statistics that show a decline in abortions. (Photo: Phil Walter/Getty Images)

This past Black Friday, the Centers for Disease Control and Prevention (CDC) published its latest numbers on abortions performed in clinics in the United States. (Black Friday was apparently a big day for scientific reports from the Trump administration.) The CDC's data showed that, in 2015, the rates at which Americans got clinic abortions fell to a historic low. In fact, CDC data indicates that abortions have been declining steadily since the mid-2000s and either fell or stayed the same, every year, in the decade before that. That all might be reason to celebrate, for many folks across the political spectrum.

But what's less well-known is that the CDC's numbers don't reflect all of the legal abortions that occur across the U.S. There are a few states, including populous California, that don't report their clinic abortions to the CDC. Plus, no major research organization has counted how many Americans are getting abortions by ordering pills over the Internet, a phenomenon that may be growing. Most of the researchers I talked to believed that America's abortion rates probably really are falling, but, critically, they don't have absolute proof of that, and it's possible that the rate of decline isn't as steep as the big national numbers make it appear.

"It seems, to me, likely that abortions are going down, but it's also very likely that do-it-yourself abortions are going up, through pills that you can easily order online," says Diana Greene Foster, a scientist who studies population trends at the University of California­­–San Francisco. "So we don't know the extent to which the total abortion rate is going down because now there's this growing, unmeasured piece."

For researchers of abortion rates, who tend to support access to abortions and contraception, the uncertainty is troubling. It means they and the health departments they work with don't know where in America there might be an unmet need for abortions—or for the devices and pills that prevent unwanted pregnancies in the first place.

"It's important to understand why the numbers are going down," says Daniel Grossman, a gynecologist who studies reproductive health access, also at the University of California–San Francisco. "My concern is that people are being forced to take matters into their own hands because they don't have access to a clinic-based service. Women should be able to access high-quality health services for any health need."

The drops in clinic abortions that the CDC—as well as the non-profit Guttmacher Institute, the other major source of nationwide abortion statistics—have recorded are significant and part of a years-long trend. In 2015, the CDC recorded about 12 women out of every 1,000, aged 15 to 44, had an abortion after seeing a licensed clinician. Compare that to 2006, when the CDC calculated a rate of about 16 abortions for every 1,000 reproductive-age American women. Guttmacher covers more of the country than the CDC, and its numbers are a bit higher. Still, they show a similar pattern: 20 abortions per 1,000 women in 2006, but 15 per 1,000 in 2014, the institute's latest available data.

The drops have spurred a lot of research and speculation into why. Studies done in Colorado and Iowa suggest that making birth-control implants and intrauterine devices (IUDs) more affordable was a big help. These set-it-and-forget-it technologies are highly effective and aren't prone to human error, so they could prevent more unwanted pregnancies that would have otherwise ended in abortion. Many researchers also argue that more access to contraceptive methods in general, provided by the birth-control mandate in the Affordable Care Act, prevented unwanted pregnancies.

Anti-abortion laws may also have played a role. Restrictive policies often aren't enough, on their own, to cut abortion rates significantly. For example, countries where abortions are illegal don't tend to have much lower abortion rates than countries where abortions are freely available. Still, these laws can make a big difference locally. One study of what happened in Texas after the state passed several strict laws found that abortions dropped by 13 percent.

Is all that enough to explain America's decreasing clinic abortion rates? Foster doesn't think so. She's unsettled, in particular, by articles that declare it's almost entirely because of more contraception. "People are just not carefully looking at the data," she says. "It just doesn't add up."

Last year, she published an opinion piece in the American Journal of Public Health, questioning whether America's drop in clinic abortions is a "public health achievement or failure." For her, it would be an achievement if public-health policies are preventing unintended pregnancies, but a failure if people can't get abortions they want, or if they're suffering from infertility, perhaps because of exposure to toxic chemicals (a hypothesis that's yet be to be tested). Lately, she's been especially concerned about the lack of data on abortion pills ordered online, which show some signs of increasing in popularity.

The idea of mail-to-your-home abortion pills made the news this past fall, when a service called Aid Access publicly announced it would start shipping to the U.S. Even before that announcement, Aid Access' founder, a doctor named Rebecca Gomperts, told The Atlantic that she had been serving patients in America for six months, during which she estimated she sent out 600 packages. And before that, some unknown number of women had been ordering pills from sketchier websites—although one recent study found that most of those sites did, in fact, send out pills with real abortion medicines in them, though sometimes in smaller amounts than advertised.

The kinds of pills that Aid Access offers, and that other websites purport to sell, are 98 percent effective at ending pregnancies eight weeks along or less. In fact, they already make up one in four abortions prescribed in clinics. Complications are uncommon, but patients may need to visit a doctor if they have symptoms like heavy bleeding or severe cramps. Pro-life groups say the online pills are dangerous, but Grossman actually considers them relatively low risk, from a health standpoint. The worst that could happen is that they don't work, delaying a woman's abortion, he says. It's unknown what legal risk people face for ordering and using these pills.

Elisa Wells, co-director of Plan C, a website with information about take-at-home abortion medications, says she's seen numbers, from advocacy groups, which suggest to her that online abortion-pill ordering "is probably growing and is probably not insubstantial." "We see this as the future of how abortion can be provided in the 21st century," she says. Foster even questioned whether America's overall abortion rates are going down, when taking online-pill procedures into account. But Grossman and Megan Kavanaugh, a scientist at the Guttmacher Institute, think the numbers likely aren't high enough to reverse the declining trend. Everyone agreed there is no good data on the pills' popularity.

There are some efforts underway to count these abortions. Kavanaugh and Grossman both say they're working on studies, but it's hard. "People are doing it in a clandestine way," Grossman says. "They don't want to be studied."

It seems irreducibly modern that Americans should now order their abortions online, but in some ways, it's a throwback too. "The reality, I think, is that people have been doing things on their own forever," Grossman says. The difference, now, is that there's a safer and more effective method available to folks anywhere with the funds and an Internet connection. What that means for America's abortion rates and demand remains to be seen.