Many studies show a retention of fetal cells after birth or even male cells in women who have never given birth. This number of cells is miniscule, leading to the term “fetal microchimerism (FMc). Here are some articles about it. What do you think about the link between women with FMc and auto-immune disorders or as it affects transplants?
http://www.bloodjournal.org/content/102/10/3465?sso-checked=true
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0045592
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2894651/  (Links to an external site.)
http://www.jimmunol.org/content/164/11/5545.short  (Links to an external site.)
http://www.theatlantic.com/health/archive/2014/10/your-babys-leftover-dna-is-making-you-stronger/381140/  (Links to an external site.)