Perhaps a mother can influence her child's biology even though she is pregnant with a donor egg

When women or couples have difficulty having children and have been through fertility treatment several times, they can resort to trying to conceive with the help of egg donation. In 2025, approximately 800 children were born in Denmark in this way.

This may increase in the future. Because from 1 January 2026, it became legal to freeze eggs, even if there is no use for them in advance.

»For most women, the last resort is to have an egg donated. They want to get some information about how much they can influence the child they are not genetically related to. Is there any way I can still influence that child while it is inside my womb? It also means something to the partner and the rest of the family,« says Line Hjort, Assistant Professor at the Department of Immunology and Microbiology (ISIM) at the University of Copenhagen.

She is heading a research project that, with support from Independent Research Fund Denmark, will investigate whether it is possible for a woman to influence a child's biological development, even if she is not genetically related to her child.

Transfer of cells between woman and child

The research focuses on two topics, epigenetics and microchimerism, respectively.

In Greek, epi means 'on top'. So, epigenetics is about small molecules sitting on top of our DNA and determining how much of our DNA is expressed and how much is shut off.

Epigenetics helps determine whether a cell should become a muscle cell, a fat cell or one of the other almost 200 different cell types we have in the body.

»You could say that your DNA is our hardware just like a computer, while epigenetics is the software that makes it play. We know that the environment, while you are in your mother's womb, means something to your epigenetics. But we don't know exactly how much,« Line Hjort elaborates.

Microchimerism is a word for cells migrating between mother and child. When a woman is pregnant, cells from the baby will pass through the placenta into the woman's blood circulation and into her tissues.

Conversely, the woman's immune cells in particular will be transferred to the child, where they can be found as living cells right up until the child turns 20.

»We know that microchimerism exists in humans, but we don't know much about the significance of the transferred cells. Therefore, we also want to measure whether there are any cells that are transferred from the mother to the child she has had with a donor egg,« explains Line Hjort.

The participants will continuously gain knowledge about the progress of the research

The research is being carried out in collaboration with the fertility clinics at Herlev Hospital and Rigshospitalet. The plan is to include up to 400 women who have become pregnant through egg donation, as well as a control group of women and families who undergo fertility treatment with their own eggs.

A blood sample must be taken from the umbilical cord immediately after birth, and again when the child is one year old. In this way, the researchers can see whether there are any epigenetic associations between woman and child, and whether they have become more or fewer during the child's first year of life.

»During the study, we will also conduct qualitative studies where we ask these women who are pregnant with donor eggs what the results will mean for them. And then we will continuously tell them what we find during the study. Then they can also help develop what kind of information you want when you consider egg donation,« says Line Hjort.

The project is expected to run for four years. Line Hjort hopes that the work can also shed light on some of the complications that occur more often in pregnancies with donor eggs than other pregnancies. For example, preeclampsia, reduced fetal growth and premature birth.

First and foremost, however, it is about what significance the mother can have for her child's development.

»With everything I know about epigenetics, I would be very surprised if we didn't see that you can influence the child you carry, even if you are not genetically related. But to what extent will be very exciting to find out. I hope that we can give these families the knowledge that no matter how you live, what you eat and how much exercise you do, it matters for which genes are expressed in the child. And then I hope that we can give a figure for how big that significance is,« concludes Line Hjort.