Alzheimer’s disease and other dementias affect nearly twice as many women as men. Around 3.5 million American women currently live with a dementia (from any cause), compared to around 1.8 million men. Why does this cognitive disorder strike women more often than men? Researchers have begun to look at how uniquely female biological factors—including hormones, pregnancy and more—may influence a woman’s risk of Alzheimer’s. But does being pregnant increase your risk for Alzheimer’s disease or decrease it? The evidence isn’t clear yet, but here’s what we know. The truth about pregnancy and Alzheimer’s risk Why would pregnancy affect a woman’s chance of getting Alzheimer’s disease, anyway? Well, pregnancy exerts a number of physiological effects on a woman’s body: estrogen levels skyrocket, and pregnancy fine-tunes the mother’s immune system regulation to tolerate the “foreign tissue” of the developing fetus. Some Alzheimer’s experts have hypothesized that either the hormonal or immunoregulatory effects of pregnancy might impact a woman’s Alzheimer’s risk. And while these factors may ultimately prove to influence dementia risk in women, the evidence so far remains anything but clear on the relationship between pregnancy and Alzheimer’s. In 2018, a large-scale investigation into the self-reported data of more than 14,000 women in the Kaiser Permanente health system in California correlated pregnancy with a decline in risk for developing Alzheimer’s later in life. In that study, researchers found that three completed pregnancies lowered a woman’s risk of dementia by 12%, compared to women with one child. A smaller study of 95 British women likewise suggested a correlation between more months of pregnancy and a reduced risk of Alzheimer’s disease. However, other studies have found that pregnancy might increase a woman’s risk of developing dementia. A 2018 study of 3,549 women from Korea and Greece associated five or more pregnancies with a higher risk of Alzheimer’s disease. Specifically, the study showed women with five or more children experienced a 1.7-fold increase in Alzheimer’s risk, compared to women with four or fewer children. Other reproductive factors might affect Alzheimer’s risk too Both of those studies looked at completed pregnancies, but miscarriage may play a role in Alzheimer’s risk too. In the Kaiser Permanente study, researchers found an association between miscarriage and increased Alzheimer’s risk. Specifically, they found that each report of a miscarriage increased a woman’s chance of developing dementia by 9% when compared to women who reported no miscarriages. On the other hand, the study of Korean and Greek women differed somewhat in its findings on miscarriage. That study showed women who had experienced incomplete pregnancies experienced a lower risk of Alzheimer’s than women who had never been pregnant. Your overall reproductive history may provide a clue to your risk for Alzheimer’s as well. The Kaiser study examined women’s overall reproductive period (the time between onset of menstruation and menopause) and found that women with a short reproductive history of 21-30 years faced an increased risk of dementia in older age, compared to women with a reproductive period of 38-44 years. Keep in mind that both of the large studies are observational and show only a correlation. Controlled studies are necessary to draw a firm line between pregnancy and risk of dementia or Alzheimer’s risk. Talking with your doctor about your reproductive history and Alzheimer’s Since the studies don’t yet offer definitive conclusions about the ways in which pregnancy and reproductive history might affect your risk of developing Alzheimer’s, how should you discuss the subject with your doctor? To help your healthcare team develop a personalized plan for managing your dementia risk, make sure your doctor knows your complete reproductive history, including: Age at onset of menstruation Age at menopause Family history of Alzheimer’s disease or another dementia Personal history of hormone replacement therapy (HRT) Number of completed pregnancies Number of miscarriages These data points can help inform the conversation with your doctor while researchers continue to investigate the potential gender-specific risk factors for Alzheimer’s disease. Together, you and your healthcare team can use the best available data, along with your personal health history to understand your risk factors for dementia. Whether you have risk factors or not, knowing the signs symptoms of Alzheimer’s disease and dementia will help you and your doctor identify the problem as early as possible so you can get the care you need.