M aternal microchimerism (MMc) in cord blood (CB) caused by the exchange of cells at the maternal–fetal interface was first described in 1995 by Hall et al. (1). To the many known immunologic consequences of maternal–fetal cell exchange and particularly, CB MMc must now be added yet another consequence: the antitumor immunotherapeutic effect of CB transplants. Surprisingly, this effect seems to...

Isolation of fetal cells from maternal blood is under active investigation as a noninvasive method of prenatal diagnosis. In the context of studying cell surface antigens expressed on fetal cells we discovered that fetal cells from a prior pregnancy also could be detected. This led to the appreciation of the persistence of fetal cells in maternal blood for as long as 27 years postpartum, and th...

Mendelian genetics presumes inheritance of fitness through DNA. Kinder et al. find that maternal microchimerism induces stable immune tolerance to non-inherited maternal antigens in offspring. Female offspring that share these antigens with their mate experience reduced fetal wasting, establishing a role for vertical transmission of non-genetic information in reproductive fitness.