A fetus's cells can and do migrate to its mother. Cells pass between a mother and a fetus during pregnancy, after which they can stay in the body and reproduce for decades, a condition called microchimerism. Researchers have found male cells in women's blood after pregnancy, and the cells are also often found in a mother's brain. A mother can also pass cells to a fetus, but this happens about half as frequently as the reverse.
Can a Fetus's Cells Migrate to Its Mother?