They found that the rate of new cancer was 24 percent lower among women who delivered 10 or more babies as compared to the general population. The reduction of cancer risk was found mainly in decreased rates of breast cancer and gynecological cancers, including ovarian and cancers of the uterus lining. In fact, for these specific types of cancers, the rate of new cases was about 50 percent lower in women with 10 or more deliveries. The team is not yet sure whether their findings apply to women who have had only one to three children, but researchers plan to conduct another study to find out.
Age factors into the study as well. The women who had 10 or more babies were approximately five years younger than the average Finnish woman giving birth to her first child. And it’s already known that becoming pregnant at a young age helps lower the risk of breast cancer. Women who give birth before age 20 have about half the risk of those whose first delivery is after age 30. The researchers suggest that pregnancy speeds up breast cell maturation, and mature cells are more resistant to cancer.
Giving birth to at least five children also reduces risk, possibly because when pregnancy halts the menstrual cycle, the breast cells of women are exposed to less estrogen. According to the American Cancer Society, estrogen exposure is thought to increase breast cancer risk.
Halting ovulation and the hormone changes that accompany it may also have a role in reducing the risks of ovarian and endometrial cancers. The researchers noted that those women who are able to have 10 or more children are likely to be healthier overall than the general population. But the researchers do concede that giving birth to five or more children comes with its own dangers, increasing the odds of pregnancy complications including premature birth and post-delivery hemorrhaging.
