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How and when does pregnancy affect breast cancer risk?

Breast cancer surgeon Dr. Maria Palafox discusses pregnancy and risk

· Pregnancy and Cancer,breast cancer,Breast Surgeon

I always like to start the discussion of pregnancy and risk the same way. Why? Because this first part is very important. Ladies - we cannot always control whether or not we have children and when we have children. Further, even when we can control certain factors around pregnancy and children, I request that you take great pause before ever making a pregnancy decision based on these risk factors. Children are a true blessing to the world and to our individual lives. It is important for us to be aware of all of our personal risk factors as we age to ensure we can be as healthy and happy as possible for as many years as we are given on this earth.

Pregnancy and Breast Cancer Risk

Many of us have heard that having children later in life increases our risk for developing breast cancer but I still often get asked really great questions on the topic. For example, what if we never have children? Does that present a higher risk than than if we have children when we are "older"? What exactly does "older" mean? Exactly how much does pregnancy increase and/or decrease our risk? Today, I will explain breast cancer risk as it relates to pregnancy with as much detail as possible.

Age at First Pregnancy and Breast Cancer Risk

Women who have their first child when they are under the age of 20 have a 50% reduced lifetime risk of developing breast cancer as compared to women who do not have any children. Women who give birth to their first child after the age of 35 have about a 40% increased lifetime risk of developing breast cancer compared to the women who had their first child under the age of of 20. Studies show that women who never have children have a slightly increased risk of developing breast cancer as compared to women who have given birth to two or more children, but a lower risk than women who only have one child and had their first child when they were over the age of 35.

When we start to think about why the risk factors increase as we age, it's important to remember that everyone's risk of developing breast cancer increases with age because the older we get, the more likely we are to have mutations in our cells. When a woman gets pregnant, her breast cells begin to multiply at a rapid pace so that they can prepare to produce milk. Thus, if the woman is older and has more mutated cells when she becomes pregnant, the greater the likelihood that these mutated cells will begin dividing and proliferating.

Number of Children and Breast Cancer Risk

In general, a woman's lifetime risk of developing breast cancer decreases with every childbirth, and it reduces even more when she has children closer together. This, however, is lifetime risk. Did you know that a woman's "short term" risk of developing breast cancer is actually increased for about 10 years following a full-term pregnancy?

The data can be very confusing and we learn more about risk factors each and every year. So what does this mean to you? The biggest thing to remember is that all of this data is extremely useful as we work to find cures, preventions, and treatments for breast cancer, but we all have some kind of risk no matter what we do. 

So if someone puts pressure on you to have or not have a child because of breast cancer risk, think about this: Just being a woman makes you 100 times more likely to develop breast cancer. Would you become a man just to avoid that risk? Of course not! So know in general where you fall in the "risk" category based on whether or not you have had children and at what age you had them, but don't let it stress you out.

Dr. Maria Palafox is a breast cancer surgeon based in South Texas and a leading expert on breast cancer and genetic testing. Her office can be reached at (210) 504-5053 or

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