Pregnancy May Change Your Risk of Developing These Health Conditions

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. If there are complications during pregnancy, it can also increase your odds of other conditions, such as heart disease.

Breast Cancer

Women who have had five or more children have half the risk of breast cancer compared with women who have never given birth, according to the National Cancer Institute (NCI). This seems to be because your periods stop during pregnancy, reducing your lifetime exposure to estrogen and progesterone.

There are variations in the theme. For instance, those 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, according to the NCI.

And individuals who breastfeed for at least a year also have a lower breast cancer risk, per the NCI, as most people 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.

Ovarian Cancer

Like with breast cancer, your risk for ovarian cancer goes down the more children you give birth to, according to the NCI. The same mechanism seems to be at work: less exposure to reproductive hormones over your lifetime. Having ever used oral contraceptives can also lower risk, per the NCI.

Breastfeeding is also associated with a lower risk of ovarian cancer, according to a pooled analysis of 13 studies published in 2020 in JAMA Oncology.

"Birth control pills, lactation, all those things reduce the number of cycles women have and that seems to be protective against ovarian cancer," said Ronald Alvarez, MD, professor, and chairman of the department of obstetrics and gynecology at Vanderbilt University Medical Center in Nashville.

However, 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, per the NCI.

Endometrial Cancer

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, according to the NCI. 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, according to the NCI.

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, according to the Alzheimer's Association.

"For a long time, we thought women live longer and that must explain it," said Heather Snyder, PhD, vice president of medical and scientific relations 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.

Another study published in 2018 in the American Journal of Alzheimer's Disease and Other Dementias 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," Snyder said.

Obesity

Having more children may have the opposite effect on your odds of becoming obese, particularly if you retain some added weight after each pregnancy.

Up to 20% of people, on average, retain more than eight pounds of weight that they gained during pregnancy beyond one year postpartum (after giving birth), according to a review published in 2021 in the Journal of Clinical Medicine. According to the review, postpartum weight retention is a strong predictor of obesity in later life with long-term health consequences, such as heart disease, diabetes, and certain cancers.

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 a child to take care of.

Heart Disease

It's not pregnancy per se that may affect your risk for heart disease, but complications during pregnancy can be a sign of future issues, according to a review published in 2016 in the European Journal of Preventive Cardiology. The review concluded that those who have had smaller 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 when it's possible. Heart disease is the leading cause of death for women, according to the Centers for Disease Control and Prevention.

A Quick Review

Pregnancy can have different effects on different people, resulting in temporary and even permanent changes. Some of the more beneficial changes include a reduced risk of developing breast cancer, ovarian cancer, endometrial cancer, and dementia.

However, one less-welcome change is weight gain, which can put you at higher odds of developing heart disease, diabetes, and some cancers. And some complications during pregnancy can raise your risk of heart disease. It's also important to remember that environmental and genetic factors can still trump the benefits that multiple pregnancies have on reduced cancer risk.

As always, it's best to discuss any questions or concerns you may have about your health—regardless of if you've been pregnant or not—with your healthcare provider. Your healthcare provider will be able to give you the best advice for your situation.