The American College of Obstetricians and Gynecologists (ACOG) officially recommends that the decision about ovary removal be made on a case-by-case basis, says Olive, who didn't work on the study. The most common reason to remove a woman's ovaries during a hysterectomy is to reduce her risk of ovarian cancer.

"The predominant teaching is that [ovary removal] in the low-risk patient should be avoided under the age of 40, should be routinely performed over age 55, and should be considered and discussed in the interval between," Olive writes.

Most women who get hysterectomies should keep their ovaries, write researchers in Obstetrics & Gynecology.

Hysterectomy is surgery to remove the uterus. Every year, about 600,000 women in the U.S. get hysterectomies, most often for noncancerous reasons, write the researchers. They included William H. Parker, MD, of the UCLA medical school.

Parker's team looked at data from studies of hysterectomy patients aged 40-80. The researchers found "no survival benefit after [removal of the ovaries during a hysterectomy] at any age" among women at average risk of ovarian cancer.