Snopes.com, a website covering urban legends, internet rumours, e-mail forwards, and other stories of unknown or questionable origin, set out to investigate the claim this meme makes- that during pregnancy, if the mother suffers organ damage, the baby in the womb sends stem cells to repair the damaged organ. Despite some mean-spirited comments about the use of the term "baby" and whether it knows it is helping its mother, the author concludes that "the science behind the claim is actually fairly solid".
The transfer and incorporation of foetal stem cells into a mother's organs is referred to as fetomaternal microchimerism, and scientists have been generally aware of it for decades. A 1996 study in Proceedings of the National Academy of Sciences, for example, found that in humans, genetically distinct cells from a male fetus persisted in the mother's body as long as 27 years after birth.
A 2015 study published in the journal Circulation Research addressed the issue of fetal stem cells actually healing maternal organs. In this study, researchers tagged mice with a fluorescent protein that allowed the researchers to trace the flow of the fetus's stem cells from the mother's placenta into its heart while they induced cardiac injury to the mother. They found that fetal stem cells directly targeted the damaged cardiac cells and fully integrated themselves into the mother's heart.