A new study from researchers at the Fundacion Instituto Valenciano de Infertilidad and Stanford University suggests infertile women who carry a child fertilized using a donor egg still impart an important genetic gift to their children. Molecules known as MicroRNAs that are secreted in the mother’s womb can change the genetic information of the child, the researchers say.

“The ‘Barker hypothesis’ suggests that ‘the womb may be more important than the home,’ emphasizing the concept that the maternal endometrium [or the mucus membrane of the womb] has a reprogramming effect on the embryo, fetus, and adult,” wrote the researchers, who believe their work supports this famous theory.

Baker Hypothesis... In Action

The heartbreak of infertility includes knowing you will never pass on your genes to your children. Nevertheless, many couples who cannot get pregnant spontaneously become parents through adoption or in vitro fertilization (using donor sperm or eggs). Rather than adopt, many infertile women choose to carry a baby fertilized with a donor egg, believing this will help them feel more connected to their future child.

Frequently these same mothers will say their donor-egg child shares some unexpected physical characteristic with them, said Dr. Felipe Vilella, a researcher the Spanish fertility clinic in a FIVI press release. Also it is believed many adult diseases originate from conditions occurring in the womb. There, endometrial fluid, which carries a variety of molecules from the mother (including microRNAs) serves as milk to a developing embryo.

Could the (pregnant) mother influence her developing baby's genetics, even though she used a donor egg?

Vilella along with Dr. Carlos Simón, FIVI’s scientific director, and their colleagues proposed microRNAs floating in a mother’s endometrial fluid might change the embryo. To investigate, the researchers examined 10 women at FIVI and measured the activity of genes within the fluid of her uterus. They found six of 27 specific, maternal miRNAs were expressed in the endometrial epithelium during the window of implantation and were released into the endometrial fluid.

Practically speaking, this means the mother’s DNA influences the way the baby develops. Her genetic material essentially helps to "decide" which of her baby's genes get turned on and off. Even more, it means the baby will acquire some DNA from the mother, even if the egg comes from another woman, as Dr. Nick Macklon, professor of obstetrics and gynecology at the University of Southampton, explained to Express.

No matter how she becomes pregnant, a woman performs an invaluable service by carrying the child. This new research suggests she also exerts a significant influence on her child's genetics, development, and lifelong health.

Source: Vilella F, Moreno-Moya JM, Balaguer N, et al. Hsa-miR-30d, Secreted by the human Endometrium, Is Taken up by the Pre-Implantation Embryo and Might Modify Its Transcriptome. Development. 2015.