“They” say that the second year after a death is the hardest. I don’t know if that’s true or not. What is true is that you’ve gotten past all of the “firsts” – the birthdays, the holidays, the weird Hallmark holidays like Mother’s Day, Father’s Day, and Grandparent’s Day. So, this is my second Mother’s Day without my daughter Zoe. My second Mother’s Day without my step-daughter Emily.

The holidays were hard – so hard that I haven’t posted anything since then. The last couple of days I have noticed that I cry more easily, just like I did when I was first grieving. Perhaps it is because Mother’s Day is Sunday. I don’t know. I’ve never done this before: this second year grieving for an inexplicable loss. I do know that I am comforted by some research I became aware of a few years ago. If you are grieving this Mother’s Day like I am, I hope you find it as comforting as I do.

There is a process called fetal-maternal microchimerism, meaning both the mother and child have small pieces of each other on the cellular level. Fetal cells have been found in mothers’ brains. A study of women who had died in their 70s found that over half of the women had pieces from the Y chromosome in their brains, probably from when their sons were in the womb. A study of mice showed that fetal cells left in the mother’s body will go to the site of injury in a heart, turning into specialized heart cells that might start beating if needed.

Other studies have found fetal cells in a mother’s bones, liver, lungs, and other organs. Science writer Laura Sanders suggests this may be a way for a child to give back to the mother. That after taking nutrients and energy from the mother during pregnancy, after causing morning sickness, heartburn, and body aches, this is a way that the fetus can provide helpful cells. The fetal cells have the potential to turn into lots of different kind of cells that, according to the studies, can help repair a damaged heart, liver, or thyroid. There is a warning attached to this good news: the fetal cells can also cause damage, possibly playing a role in autoimmune disorders.

Sanders also points out that fetal cells may migrate early in pregnancy, meaning that even miscarriages and fetal demises can leave their cellular mark on a mother. This is heart mending news for those of us who have lost children too soon. Our mothers and our children do live on within us in ways we are just beginning to understand.

This comforts me. I am comforted by knowing that both my mother and my daughter continue to live on in me at the cellular level. I hope it comforts you, too.