Abortions are just as safe when performed by trained nurse practitioners, midwives and physician assistants as when doctors do them, a new review of the evidence suggests.

Researchers analyzed five studies that compared first-trimester abortion complications and side effects based on who performed the procedures in close to 9,000 women - and typically found no differences.

"As access to abortion is increasingly restricted, the including of non-physicians in the pool of providers is really vital because fewer and fewer people will have access as there are more and more barriers," said Amy Levi, a professor of midwifery at the University of New Mexico in Albuquerque.

Having trained nurses and midwives perform abortions could also allow some women to get care before they would be able to see a doctor - and earlier access typically means fewer complications and better outcomes, Levi said.

That's especially the case in developing countries, where doctors who perform abortions may be few and far between.

In studies conducted in clinics and hospitals in Asia, Africa and the United States, procedures supervised by nurses or midwives and doctors had similar rates of incomplete abortion, incorrect determination of the fetus' age and complications such as bleeding and injuries to the uterus.

For example, in one study of about 1,400 women getting an abortion in Vermont or New Hampshire, there were complications in 2.2 percent of procedures with a physician assistant and 2.3 percent with a doctor.

Nathalie Kapp from the World Health Organization in Geneva, Switzerland and her colleagues said the findings don't apply to nurses and midwives who perform abortions without access to emergency care nearby, or to abortions done after the first trimester.

They published their findings in BJOG: An International Journal of Obstetrics and Gynaecology.

According to the Guttmacher Institute, a sexual and reproductive health organization, 39 states require abortions to be performed by a licensed physician. And Levi, who was not involved in the new study, said only a few allow non-physicians to perform abortions both surgically and medically (with drugs).

But the findings are "really powerful" in other parts of the world, where unsafe abortion is one of the leading causes of maternal death and non-physician providers far outnumber doctors, said Levi, who wasn't involved in the new study.

They are also consistent with her expectations after working for a California-based program that trains nurse practitioners, midwives and physician assistants to perform abortions safely, she told Reuters Health.

"Access to safe abortion is imperative for reducing maternal mortality worldwide," Levi said.

"We need to keep the conversation embedded in women's health care, which is where it belongs, and I think this kind of data will help."