In women with a history of mental illness such as schizophrenia and bipolar disorder, getting an abortion does not increase their chances of landing in a psychiatric facility again, suggests a new study from Denmark.

Still, those who had an abortion had a higher overall readmission rate both before and after the procedure than women who gave birth.

Some researchers have suggested that aborting a fetus can take a serious psychological toll on women, although doctors who do the procedures argue that's generally not the case.

"We're not saying that this group of women is necessarily doing really, really well. What we're saying is that the procedure itself doesn't seem to be associated with a higher risk of readmission," said Trine Munk-Olsen, from the University of Aarhus, one of the study's authors.

"It does seem to be a more vulnerable group of women," she told Reuters Health.

Munk-Olsen pointed out that her study only took into account psychiatric episodes that were severe enough to require intensive treatment, so it can't give any clues into whether abortion might have an effect on more mild depression, for example.

Feelings of sadness and loss around the time of an abortion are "temporary and appropriate," said Dr. Anne Davis, an ob-gyn at the Columbia University Medical Center in New York.

"There are going to be normal emotional reactions to that type of stress," Davis, who wasn't involved in the new study, told Reuters Health. That's not the same thing as saying women are likely to have serious mental health issues as a result of the procedure, she added.

The new data come from records of Danish women with a past psychiatric facility stay who had an abortion or gave birth between 1994 and 2007. In each of those cases, the researchers tracked the woman's chance of being readmitted for any psychiatric disorder in the nine months before the abortion or birth and the year afterward.

Of the 2,838 women getting a first abortion, 11 percent were readmitted sometime during the study. That compares to just five percent of the 5,293 women who gave birth.

However, women who had an abortion were no more likely to be sent back to a psychiatric facility around the time of the abortion or afterward than in the months before the procedure—including before women became pregnant.

That suggests that some of these women may have in part decided to have an abortion because of psychiatric problems and related life stressors—not that the abortion itself worsened their mental illness, Munk-Olsen and her colleagues wrote Monday in the Archives of General Psychiatry.

By comparison, rates of readmission were higher after having a baby than before in women who gave birth, peaking in the first month after their babies were born.

That's consistent with prior research, Munk-Olsen said, and may be due to a mix of genetic risks and sleep deprivation, biological changes and hormone swings that happen after childbirth.

She said that the generally higher rate of psychiatric readmission in the abortion group, up to nine months before and a year after the procedure, might explain why some previous studies have suggested abortion does increase the risk of mental health problems.

Though there's still some controversy in the field, one expert not involved in the new research said the findings are consistent with past high-quality studies.

"All the things that make women think this is not the time to have a baby are risk factors for having mental health problems," said Dr. Nada Stotland, a psychiatrist at Rush Medical College in Chicago.

"The best predictor of your mental health after an abortion is your mental health before an abortion," she told Reuters Health. "Abortion may be linked to mental health problems, but it does not cause mental health problems."

The new study was partially funded by the Susan Thompson Buffett Foundation, the charitable organization founded by Warren Buffett.

Munk-Olsen said it's impossible to be sure whether the findings would be consistent in another country such as the United States. In Denmark, she said, abortion is free, legal and not highly stigmatized.