Major complications of abortion are not just the domain of medicine, they also play a significant role on the rhetorical battlefield of the perennially heated abortion debate. Anti-abortion organizations tend to tend to propagate the idea that the procedure is dangerous and unproven. The National Right to Life Committee, for example, asks the leading question “Is Abortion Safe?”on its website before listing all possible physical complications of the procedure. Planned Parenthood, on the other hand, describes abortion as “very safe.” Is the Right right? Or is abortion safe for women?

A new study released today in Obstetrics & Gynecology could close this contentious question for good. After looking at data from over 50,000 women who received abortions under California’s fee-for-service Medicaid program (Medi-Cal) in 2009 and 2010, researchers at UC San Francisco (UCSF) have determined that major complications occur less than a quarter of one percent of the time, “about the same frequency as colonoscopies,” they note. Although these findings align with those of previous studies, this new study is noteworthy because it analyzes a large sample of women after the fact, thereby circumventing the common methodological problem of retaining participants without any loss to follow-up. It is also the first study to thoroughly examine emergency department use for post-abortion care.

In the entire data sample, the researchers found that only 126 women had suffered major complications from abortion—defined as complications that require hospital admission, blood transfusions, or surgery—within six weeks of the procedure. At 2.1 percent, the rate of minor complications was substantially higher but that frequency, as the researchers observe, is still much lower than the complication rate of childbirth. The researchers also confirmed two previously established conclusions about abortion complications, noting that both women in their 30s and women who receive medication abortions as opposed to surgical abortion are more likely to experience complications.

If less than a quarter of one percent still sounds like too much risk, the researchers also suggest that the complication rate in the study could be “overestimated” based on certain features of their sample. In particular, the women followed in the study are primarily lower-income women with a potentially higher number of health problems who also rely on Medi-Cal for medical treatment. If wealthier people with private insurance were included, the authors speculate, the percentage of both major and minor complications could drop.

In addition to settling a longstanding debate over the safety of abortion, these new findings from UCSF are also poised to have a palpable political effect at a moment when abortion rights advocates have been losing some key ground. Indeed, the Right’s incendiary rhetoric surrounding abortion complications is intended to do more than just scare women, it is aimed at state legislatures as well.

More alarming still is just how successful they have been in their efforts to pass abortion regulations under the guise of protecting women from complications that have a remarkably low incidence. According to the Guttmacher Institute, 24 states have passed regulations for abortion providers that “go beyond what is necessary to ensure patients’ safety.” Almost all of these 24 states hold abortion providers to the same standards as ambulatory surgical centers, with several of them mandating the size of procedure rooms and the width of corridors. Sixteen states have regulations that apply equally to abortion providers who only offer medication abortion, even though they do not conduct surgical abortions. And 14 states require abortion providers to have formal relationships with local hospitals, which effectively gives those hospitals “veto power over whether an abortion provider can exist.” For some mysterious reason, colonoscopy providers are not held to these same standards despite a similar rate of complications.

In the post-Roe era, the Right has used this regulatory state legislation to close abortion clinics in a roundabout way, by requiring that their facilities conform to certain dimensions and by putting them at the mercy of local hospitals in conservative areas. If abortion can’t be criminalized, the logic goes, it can certainly be eliminated.

As of July, Mississippi has one remaining abortion clinic after state legislation required all physicians at abortion clinics to obtain admitting privileges at a local hospital. All but eight clinics in Texas were closed earlier this year due to similar legislation until an October Supreme Court decision blocked the law without further explanation. Even after this intervention, Texas only has about one abortion clinic for every 16,000 square miles, forcing many Texan women to travel long distances to receive proper care. What was once a debate over the legality of abortion has become a bitter turf war, with the specter of complications at the center of attempts to regulate it out of existence.

But as the fight over this new era of abortion regulation begins to garner the attention of the highest judicial body in the U.S., this study from UCSF could play a critical role in undermining the rationale of risk used by the anti-abortion Right.

As Dr. Ushma Upadhyay, an assistant professor in the Advancing New Standards in Reproductive Health program in the Department of Obstetrics, Gynecology and Reproductive Sciences at UCSF, writes: “Abortion is very safe as currently performed, which calls into question the need for additional regulations that purportedly aim to improve safety."

In the study itself, the UCSF researchers also express their hope that their conclusions will “inform policy debates” by helping legislatures to “[weigh] any theoretical incremental reduction in patient risk that may occur against any increases in risk that may occur with reduced access to abortion care.”

In other words, unnecessarily stringent abortion regulation could be far more dangerous than abortion itself. Given that the World Health Organization and the Guttmacher Institute have jointly found that abortion remain relatively constant irrespective of its legality, restricting access abortion only seems to make it more dangerous. Abortion can be criminalized but it won’t be eliminated.

Worldwide, for example, 20 million women with unintended pregnancies undergo unsafe abortions, 68,000 of whom die, and 5 million of whom experience long-term complications that require hospitalization. This quarter of women who experience major complications from unsafe abortions contrasts starkly with the less than one quarter of one percent of women who experience complications from safe abortions.

And although the rate of unsafe abortion in the U.S. is negligible, these statistics are still a cautionary tale for a country in which thousands of deaths from unsafe abortion prior to 1973 are an all too recent history. More than forty years after Roe, this new study could help to stem the tide of encroaching abortion regulation by finally putting the myths surrounding its risks to rest.