Scientific publisher Sage Journals has retracted three papers on abortion—including a controversial 2021 study on mifepristone, the medication at the center of a US legal battle.

The 2021 study found that mifepristone, one of two pills used in a medication abortion, significantly increased the risk of women going to the emergency room following an abortion. The study, along with another retracted paper from 2022, was cited by US District Judge Matthew Kacsmaryk in the April 2023 ruling that invalidated the Food and Drug Administration’s approval of the drug.

Mifepristone was approved in 2000 by the Food and Drug Administration, the federal agency that evaluates the safety and efficacy of drugs, and has been used by at least 5.9 million women in the US since then. The drug blocks a hormone called progesterone that’s needed for a pregnancy to continue. It’s used alongside another pill, misoprostol, to induce an abortion within 10 weeks of pregnancy.

The three retracted studies were published in the journal Health Services Research and Managerial Epidemiology in 2019, 2021, and 2022. In July 2023, Sage issued an “expression of concern” about the 2021 paper, saying it was launching an investigation into the article.

According to Sage, a reader contacted the journal with concerns about misleading presentations of data in the 2021 article on mifepristone. The person also questioned whether the authors’ affiliations with pro-life advocacy organizations, including the Charlotte Lozier Institute, present conflicts of interest that the authors should have disclosed in the article.

In a retraction notice published on February 5, Sage said an independent reviewer with expertise in statistical analyses evaluated the concerns and concluded that the article’s presentation of the data in certain figures leads to an inaccurate conclusion. The reviewer also found that “the composition of the cohort studied has problems that could affect the article’s conclusions,” according to Sage.

As part of the publisher’s investigation, Sage said, two subject matter experts conducted an independent post-publication peer review of the three articles and found that they “demonstrate a lack of scientific rigor.” In the 2021 and 2022 articles, the reviewers found problems with the study design and methodology, errors in the authors’ analysis of the data, and misleading presentations of the data. In the 2019 article, the experts identified unsupported assumptions and misleading presentations of the findings.

“The retractions are not scientifically warranted as is easily demonstrable to any trained, objective scientist,” James Studnicki, the lead author on all three studies, told WIRED via email.

Studnicki, the vice president and director of data analytics of the Charlotte Lozier Institute, shared with WIRED a copy of a point-by-point rebuttal he and his coauthors submitted to Sage in response to the retractions.

In the 2021 study on mifepristone, Studnicki and his coauthors used data from Medicaid claims of 423,000 medication and procedural abortions between 1999 and 2015. Of those, over a quarter visited a hospital emergency room within 30 days of the abortion. During the study period, they found that emergency room visits associated with medication abortion rose much faster when compared to rates following a surgical abortion.