Reproduction linked to cancer risks

When my friend was diagnosed with breast cancer shortly after giving birth to her 2nd child, she thought it was just bad luck. A few months later, she realized that she knew quite a few people who had developed breast cancer after giving birth and who were also over 35. She started to come to the conclusion that it couldn’t be coincidence, and as she started to dig a little deeper, she uncovered studies that linked age at birth of first child with an increased risk of developing breast cancer.

Apparently, the risk of breast cancer increases slightly after giving birth for anyone, regardless of age, due to the rapid growth of cells during pregnancy. And if you have any deformed cells (which is more likely if you are older), they will also duplicate more quickly. But with each passing year after giving birth, the risk goes down, and after 10 years of giving birth to your last child, the chance of developing breast cancer decreases to less than if you had never had children.

However, if you are over 35 when you give birth to your first child (and some studies even push that age down to 30), then the chance of developing breast cancer is actually greater than if you had never had children, and you don’t get the benefit of that 10 year protection (the science isn’t clear as to why though). But if you have your first child before 35, for each child you have and each year you breast feed (without getting your period) your risk of breast cancer 10 years after the birth of your last child goes down. Not confusing at all, right?

Upon looking into this a bit more and trying to make sense of it all, I came across a few other reproductive links to cancer. If you get your period before the age of 12 or go into menopause after the age of 55, your chances of breast cancer increase because of the increased amount of estrogen you are exposed to over the course of your life. But being on an oral contraceptive more than 5 years (as long as you don’t start in your teenage years) reduces your chance of endometrial and ovarian cancer by 50%.

Scientist haven’t been able to uncover why there are so many footnotes and caveats to the “rules” which may explain why this information is not more prevalent. And a lot of this is random – other than controlling your weight and watching your sugary drink intake, you can’t control when you get your period or stop getting your period…. and when you decide to have kids can’t be dictated by cancer mitigation, but knowledge is indeed power. As my friend said, at least knowing the odds would have prevented her from being blindsided when she was diagnosed. If she had been aware of the risks, it wouldn’t necessarily have changed her timing for having children, but she could have made an informed decision and been on the look out for signs or symptoms.


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