Abstract

This paper is a detailed review by experts in the field of microchimerism. Fetal cells cross from the baby into the mother’s blood-stream during pregnancy, and persist in her body for years afterwards. The cells involved are varied; there is evidence that stem cells are also involved. Free fetal DNA thought to be of placental origin also circulates in the pregnant woman’s blood during pregnancy, and this DNA is now used to access the baby’s DNA during pregnancy and look for genetic disorders. This traffic of cells and DNA is known to occur in both directions, although the amount is more significant from baby to mother during pregnancy.  This review examines the evidence (from humans and in animal studies) around whether fetal cells persisting in the mother after pregnancy are beneficial or detrimental to maternal health, or instead are just co-incidental. The paper also looks at the role that maternal cells play in development of the baby’s immune system, and how this might be of use in transplant medicine. In both, there are lifelong consequences to the exchange of cells and DNA between mother and baby in pregnancy, and this connection has potential applications in states of health and disease.