Impact of Male-Origin Microchimerism on Cardiovascular Disease in Women: A Prospective Cohort Study.

Increasing parity is associated with an increased risk of ischemic heart disease (IHD) and stroke in women. This is probably attributable to biological responses of pregnancy. Male cells of presumed fetal origin are commonly present in women years after pregnancy-a phenomenon termed male-origin microchimerism (MOM). In this study, we investigated whether MOM was associated with risk of IHD and ischemic stroke in women. We evaluated the association between MOM and ischemic events in a cohort of 766 Danish women enrolled in the Diet, Cancer and Health cohort during 1993-1997 when aged 50-64 years. Of these women, 545 (71.2%) tested positive for MOM through targeting of the Y chromosome (DYS14 DNA sequence) in their blood. Multiple Cox regression models were used to calculate hazard ratios with 95% confidence intervals. We found that MOM was associated with a significantly reduced rate of IHD (hazard ratio = 0.44, 95% confidence interval: 0.23, 0.83) but not ischemic stroke (hazard ratio = 0.80, 95% confidence interval: 0.46, 1.41). Our findings show that microchimerism positivity is associated with a lower rate of later IHD development in women. Although the underlying mechanisms are presently unknown, MOM may be relevant in women's cardiovascular health. More studies are needed to confirm these findings.