Mothers May Harbor Living Fetal Cells in their Brains for Decades

A long-running line of research shows fetal cells can persist in a mother's body after pregnancy, including the brain, sometimes as intact cells carrying male DNA; a 2012 study found male DNA in brains of women who had male pregnancies, with a 94-year-old case showing high signal, and later work confirms bidirectional cell traffic and links to autoimmune conditions and tissue repair, though mechanisms are unclear and larger studies in ordinary brain tissue are needed.