Does Breastfeeding Lower the Risk of Ovarian Cancer?

We often focus on how breastfeeding helps the baby, but what about the moms? Many women report that breastfeeding their babies makes them feel less stressed and anxious. Breastfeeding also benefits a mom’s heart by lowering her blood pressure. But can breastfeeding lower a mom’s risk of developing ovarian cancer too?¹

Background on ovarian cancer

Most ovarian cancer begins in the ovaries. These are the reproductive organs where eggs are stored. Early-stage ovarian cancer often has few symptoms. As the condition progresses, symptoms may be more noticeable, including:²

• Bloating
• Belly pain
• Frequent urination
• Feeling full quickly after a meal

More than 2 dozen studies show mixed results about links between breastfeeding and ovarian cancer. Some have found that breastfeeding reduces the risk of developing ovarian cancer, while others found no link.³

But a new study tips the needle once more toward breastfeeding’s protective benefits against cancer.³

Breastfeeding found to lower the risk of ovarian cancer

The new study looked for links between breastfeeding and epithelial ovarian cancer. This is the most common type of ovarian cancer. About 9 out of 10 tumors found in the ovaries are epithelial. This means the cancer starts in the outer layer of cells covering the ovaries.³

The researchers looked at the breastfeeding history of nearly 9,975 moms with ovarian cancer and nearly 13,850 moms without it. They evaluated:³

• The length of time the mothers breastfed their infants
• Their ages when they started and stopped breastfeeding
• How much time had passed since their last breastfeeding phase

The researchers found that breastfeeding for just 1 to 3 months was linked to an 18 percent lower risk of ovarian cancer. Breastfeeding for 12 or more months was linked to a 34 percent lower risk. In other words, the longer a mom breastfed, the more her risk of developing ovarian cancer declined.³

Researchers also found that breastfeeding for any length of time in moms with 2 or more children was linked to a reduced risk of ovarian cancer. Moms with only 1 child needed to breastfeed for at least 6 months to see a reduced risk of invasive ovarian cancers. The findings held true even for the high-grade serous subtype, which is the deadliest type of ovarian cancer.³

Are these findings trustworthy?

While the new study offers detailed information on breastfeeding patterns and a large sample size, a few things limit its findings.³

First, studies that measure links between 2 conditions can only show how strongly linked 2 conditions are. They do not prove that 1 (breastfeeding) causes the other (reduced risk of ovarian cancer). Second, the study relied on women’s own recollections of breastfeeding over a 20-year time period. The danger here is that people do not always remember things the way they happened. Distortions in memory recall could magnify the true effect being measured.^3,4

What does it all mean?

Unfortunately, we still cannot be certain that breastfeeding reduces a woman’s risk of ovarian cancer. Researchers need to learn how specific biological pathways in the body linked to breastfeeding interact with the factors that lead to ovarian cancer.⁴

With these limitations in mind and given the mixed results of other studies, it is fair to wonder what these new findings mean. Perhaps the most exciting contribution is that it identifies a specific action people can take to lower their risk of ovarian cancer. The only other proven action is to take oral contraceptives. Adding breastfeeding to the list gives people a new tool to improve their odds against ovarian cancer.³

Should I breastfeed?

Breastfeeding is a personal choice that includes many factors. Some babies and some moms have trouble breastfeeding and must use other means for nourishment, like bottle feeding with formula. And that is okay. Breastfeeding may offer you some protection against developing ovarian cancer if you:

• Have a family history of ovarian cancer
• Have a certain genetic mutation that places you at risk
• Can breastfeed your baby and chose to do so

If you have questions about your ovarian cancer risk, talk to your doctor.