Scientists have unveiled another benefit to waiting to have kids: Women who give birth after the age of 30 are less likely to develop endometrial cancer.

A new study out of the Keck School of Medicine at the University of Southern California examined 8,671 cases of endometrial cancer and 16,562 control subjects, and found women who give birth after 30 are 44% less likely to develop the disease than those who give birth before they turn 25.

“While childbearing at an older age previously has been associated with a lower risk of endometrial cancer, the size of this study definitively shows that late age at last birth is a significant protective factor after taking into account other factors known to influence the disease — body weight, number of kids and oral contraceptive use,” Veronica Setiawan, lead investigator, said in a statement.

The study posits three possible theories to explain its findings:

Women who can become pregnant at an older age may already possesses healthier endometriums.

Exposure to the hormone progesterone during pregnancy may help fight off endometrial cancer during critical a period in the disease’s development. Endometrial cancer tends to strike older women.

Premalignant or malignant cells of the uterine cavity’s mucosal lining, which are more common in older women, may be shed during childbirth.

“This study shows an important protective factor for endometrial cancer, and when the exact mechanism by which it protects women from getting the disease is known, it can help our understanding of how endometrial cancer develops and thus how to prevent it,” Setiawan said.

Endometrial cancer forms in the tissue lining the uterus. It can be treated with surgery, though survival rates vary depending on how early it’s diagnosed.