Today is my youngest child’s birthday. As my mother used to tell me, we always carry our children in our hearts. I know this is true emotionally. Apparently it’s also true on the physical level.

Sometimes science is filled with transcendent meaning more beautiful than any poem. To me, this new research shows the poetry packed in the people all around us.

It’s now known that cells from a developing fetus cross the placenta, allowing the baby’s DNA to become part of the mother’s body. These fetal cells persist in a woman’s body into her old age. (If she has been pregnant with a male child it’s likely she’ll have some Y-chromosomes drifting around for a few decades too). This is true even if the baby she carried didn’t live to be born. The cells of that child stay with her, resonating in ways that mothers have known intuitively throughout time.

Fetal cells you contributed to your own mother may be found in her blood, bone marrow, skin, kidney, and liver. These fetal cells appear to “treat” her when she is ill or injured. Researchers have noticed the presence of these cells in women diagnosed with illnesses such as thyroid disease and hepatitis C. In one case, a woman stopped treatment against medical advice. A liver biopsy showed “thousands of male cells” determined to be from a pregnancy terminated nearly 20 years earlier. These cells helped her body recover just as fetal cells you gave your mother rush to help repair her from within when she’s unwell.

Fetal cells may influence a woman’s autoimmunity, although it’s not yet known if they are always beneficial. According to fascinating accounts in Do Chocolate Lovers Have Sweeter Babies?: The Surprising Science of Pregnancy , the more fetal cells there are in a woman’s body, the less likely she is to have conditions such as multiple sclerosis and rheumatoid arthritis. That’s not always the case. It’s thought that sometimes a mother’s body may instead battle those cells, thus provoking autoimmune disorders. (Apparently family dynamics are complicated even at the cellular level.)

There’s evidence that fetal cells provide some protection against certain cancers. For example, they’re much more prevalent in the breast tissue of healthy women than in those with breast cancer. Fetal cells are less common in women who developed Alzheimer’s disease, suggesting they provide late-life protection. Fetal cells can contribute stem cells, generate new neurons in the mother’s brain, even help to heal her heart. Her heart!

Look around at your family. Any woman who has ever been pregnant, even if she miscarried so early she never knew she was with child, is likely to be a microchimera (a person who carries the cells of another person). Fetal cells have the imprint of her child’s father and his ancestry. Fetal cells can be shared from one pregnancy to another, meaning the cells of older siblings may float within younger siblings. These cells are another reminder of the ways we are connected in a holographic universe.

Overall, the presence of fetal cells in a woman’s body is associated with substantially improved longevity, with an overall mortality rate 60 percent lower than women whose bodies don’t contain such cells.

I’d like to think that my fetal cells helped my mother battle the congestive heart failure that eventually took her life. I like to consider that I carry within me my older sister’s fierce intelligence and that my talented younger brother benefits in some way from the cells of both his sisters. Knowing that I carry the cells of my four living children as well as babies I lost makes my heart ever more full on this special day.

We heal our mothers and our children heal us. Again poetry takes a back seat to nature’s awesome secrets.