Having children changes your life, your priorities and, for mothers, possibly even your brain. In pregnant women, fetal cells '� which are genetically distinct from the mother's cells '� can actually establish themselves in the mother, creating a phenomenon called fetal microchimerism. Research recently published in PLOS ONE showed that fetal cells may even be able to cross the blood-brain barrier. The study found evidence of male DNA in several regions of women's brains and cerebrospinal fluid, and a likely explanation is that this microchimerism originated when the women were pregnant with a son, although other sources are plausible. The health implications of microchimerism in the brain are not well known but for better or worse, moms seem to literally carry their children with them long after giving birth. While not as literal as sharing cells, the mother '� child bond has significant psychological implications as well.� A study of children with anxiet...