We’ve long known the risks of childbirth later in life—but now it appears there may be some benefit, too. Women who give birth to their last child after age 30 have a reduced risk of endometrial cancer, according to the results of a study published in the American Journal of Epidemiology.
Endometrial cancer—also called uterine cancer—occurs in the tissue lining the uterus and is one of the most common gynecological cancers in women, with more than 47,000 new cases and more than 8,000 deaths from the disease each year.
To evaluate the relationship between childbirth and risk of the cancer, researchers analyzed data from more than 8,600 women with endometrial cancer and more than 16,500 without the disease. They found that the risk of endometrial cancer decreased after age 30—and continued to decrease by about 13 percent for each five-year period after.
Women who gave birth to their last child between the ages of 30 and 34 had a 17 percent reduced risk of endometrial cancer compared to women who had their last child before age 25. What’s more—women who gave birth to their last child between ages 35 and 39 had a 32 percent reduced risk and those who gave birth to their last child at age 40 or older had a 44 percent reduced risk. The protective effect persisted for many years and was the same for both types of endometrial cancer—type 1 is more common and type 2 is more rare and aggressive.
The large study size provides ample evidence that late age at last birth is a significant protective factor against endometrial cancer. More research will be necessary to confirm the data—especially in relationship to race/ethnicity, as the association appears to be stronger among white and Hispanic women and weaker among black women.
Setiawan VW, Pike MC, Karageorgi S, et al. Age at Last Birth in Relation to Risk of Endometrial Cancer: Pooled Analysis in the Epidemiology of Endometrial Cancer Consortium. American Journal of Epidemiology. 2012; 176(4): 269-278.