Pregnancy History Plays a Role in Alzheimer Disease Risk

pregnant woman drinking water
pregnant woman drinking water
The researchers investigated whether the potential relationship between pregnancy and AD risk was linked to an immunologic mechanism.
The following article is part of conference coverage from the 2018 Alzheimer’s Association International Conference in Chicago, Illinois. Neurology Advisor’s staff will be reporting breaking news associated with research conducted by leading experts in neurology. Check back for the latest news from AAIC 2018.

CHICAGO – Pregnancy appears to confer a reduced risk for Alzheimer disease (AD), and alterations in the immune system seem to be a contributing factor to this risk reduction, according to findings presented at the 2018 Alzheimer’s Association International Conference, held July 22-26, 2018 in Chicago, Illinois.

“Pregnancy is associated with improvement in immunoregulation that, potentially, persists into the geriatric phase of life,” the researchers wrote. “Women with higher gravidity may experience increased regulatory T-cell frequencies in the long-term. Such an increase in immunosuppressive function might protect against AD pathogenesis, because depleted immunoregulatory mechanisms have been implicated in AD aetiology.”

Molly Fox, PhD, of the University of California, Los Angeles, sought to identify an association between pregnancy history and risk for AD in a cross-sectional analysis of 133 elderly British females. Additionally, the researchers investigated whether the potential relationship between pregnancy and AD risk was linked to an immunologic mechanism. Participants’ reproductive history data were collected, and investigators measured the prevalence and degree of AD dementia which occurred in the cohort.

According to an analysis adjusted for age at first birth, breastfeeding, reproductive span, marriages, and occupation, cumulative months pregnant represented a significant AD risk predictor. Specifically, the investigators observed a 5.5% decrease in the risk of AD for each additional month pregnant (P =.02). Additionally, there was a 4.7% decrease in AD risk for each additional pregnancy month following adjustment for parity (P =.03).

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After adjustment for the number of third trimesters, the investigators found that the cumulative number of first trimesters also significantly correlated with a lower AD risk (P <.01). Comparatively, the cumulative number of third trimesters exhibited no significant effect on AD risk following adjustment for first trimesters (P =.31).

According to the researchers, “Our observation that more first-trimesters (but not third-trimesters) conferred protection against AD is more consistent with pregnancy’s persisting immunological effects, which are driven by early gestational physiology, than the oestrogenic exposures associated with pregnancy, which are greatest in late gestation.”

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Fox M. Women’s pregnancy history may influence Alzheimer’s risk through alterations in immune function. Presented at: 2018 Alzheimer’s Association International Conference. July 22-26, 2018; Chicago, IL. Abstract 25107.