This could be avoided if, instead of using hormones to stimulate the person’s ovaries to release mature eggs, doctors could remove pieces of the ovaries themselves and somehow obtain mature eggs in the lab. This would mean taking immature eggs and coaxing them in their development to the stage where they can be fertilized by sperm.
This has already been achieved in some people who have survived cancer. Some cancer treatments are toxic, particularly to eggs and sperm. Adults are often advised to save healthy eggs or sperm before beginning these treatments. But that’s not an option for kids who haven’t hit puberty yet.
However, when children have parts of their ovaries removed, some clinics have been able to use that tissue to later create mature eggs and fertilize them with sperm, with the resulting embryo being reimplanted in the same people in adulthood. The technique appears to be working and healthy babies have been born. Last year, three US-based reproductive medicine societies issued a statement concluding that the technique should no longer be considered experimental.
The technique hasn’t yet been used to help transgender people have babies, but Christodoulaki and her colleagues think it may be. To find out, they tried the approach in ovaries donated by trans men.
The team started with ovaries donated by 14 transgender men, ages 18 to 24, who had had their organs removed as part of their gender-affirming treatment. All participants had been on testosterone therapy for an average of 26 months, and some were also taking medication to stop their menstrual cycle.
First, the team removed eggs that were days away from being released by the ovaries. The team repeated the process using similarly immature eggs donated by cis women. After 48 hours in a lab dish, the eggs appeared ready to be fertilized with sperm.
In both cases, about half of the immature eggs were successfully matured in the laboratory. But something seemed to go wrong when the team tried to fertilize the eggs with sperm. While 84% of cis women’s eggs could be fertilized, it was only about 45% for trans men.
By the time the embryos were five days old — when they would normally be transferred into a person’s uterus — only 2% of the embryos created from the eggs of trans men were alive, compared to 25% of the embryos from the Cis female eggs.