Here's how your reproductive history factors into your future health.
Having kids can undoubtedly bring tons of happiness to your life, but getting pregnant and giving birth may also confer at least one slightly more surprising benefit: Research shows that having more children can actually protect women against multiple health woes, such as certain types of cancer and possibly even dementia.
Just like with parenting, there are ups as well as downs here: Multiple pregnancies can also increase your odds of other conditions, including obesity. Read on to discover the many changes pregnancy can bring to your health–way after your baby is born.
Women who have had five or more children have half the risk of breast cancer compared with women who have never given birth. This seems to be because your periods stop during pregnancy, reducing your lifetime exposure to estrogen and progesterone.
There are variations on the theme. For instance, women who have their first baby before they turn 20 have half the risk of hormone receptor-positive breast cancer compared with women who wait until after 30. And women who breastfeed longer also have a lower breast cancer risk, as most women don’t get their periods while breastfeeding, either. Breastfeeding might also change breast cells in a way that may make them less likely to develop malignancies.
Like breast cancer, your risk for ovarian cancer goes down the more children you give birth to. The same mechanism seems to be at work: less exposure to reproductive hormones over your lifetime. Oral contraceptives and breastfeeding can also lower the risk of ovarian cancer.
“Birth control pills, lactation, all those things reduce the number of cycles women have and that seems to be protective against ovarian cancer,” says Ronald Alvarez, MD, professor and chairman of the department of obstetrics and gynecology at Vanderbilt University Medical Center in Nashville.
Before you freak out: The increase from not having children (or not having many children) isn’t as significant as other risk factors. Genetic mutations, namely BRCA1 or BRCA2, put you at the highest risk of developing both ovarian and breast cancer, Dr. Alvarez points out.
Endometrial cancer is cancer of the lining of the uterus. Add it to the list of malignancies for which risk goes down with more pregnancies. Again, it’s the reduction in hormone exposure due to fewer menstrual cycles that seems to explain the change.
Of course, the number of children you have is hardly the only factor affecting risk for this and other forms of cancer. Others include your age, diet and exercise habits, family history, and in some cases, your weight.
Meanwhile, scientists have found that your risk for colorectal and lung cancer aren’t connected to the number of children you have, nor to the amount of time you’ve spent breastfeeding.
Dementia and Alzheimer’s disease
Research is emerging to suggest that your reproductive history may influence your risk of dementia and Alzheimer’s disease. About two-thirds of people with Alzheimer’s are women.
“For a long time, we thought women live longer and that must explain it,” says Heather Snyder, PhD, senior director of medical and scientific operations at the Alzheimer's Association.
It turns out there’s much more to it than that, as suggested by preliminary research presented at the 2018 Alzheimer’s Association International Conference. In one study, women who had had three or more children showed a 12% lower risk of dementia than women with one child. Miscarriages, on the other hand, increased dementia risk. Another study reported that your risk for Alzheimer’s decreases the more months you spend pregnant, perhaps because of changes that happen in your immune system while you’re expecting.
“This is something we should all be aware of and all thinking of,” says Snyder.
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Having more children has the opposite effect on your odds of being obese: In one study, the rate of obesity in women went up 11% with each successive child.
No one knows for sure why this might be. Insulin resistance, which is associated with pregnancy, can contribute to weight gain. It could have to do with hormonal changes or “baby weight” that doesn’t go away. Mothers may also eat and exercise differently after pregnancy simply because they now have children to take care of.
It’s important to note that obesity also ups your chances of developing other ailments later in life, especially diabetes, heart disease, and certain cancers.
It’s not pregnancy per se which may affect your risk for heart disease, but complications during pregnancy can be a sign of future trouble. Research has shown that women who have had smaller-than-normal babies, preterm delivery, preeclampsia (high blood pressure while you’re pregnant), and gestational diabetes may be more likely to have cardiovascular disease down the road.
Some researchers have noted that women who have these complications seem to have had not-yet-noticeable vascular and metabolic problems before they got pregnant. This would represent just another reason to prevent these complications during pregnancy. Heart disease is the leading killer of women.