A 34-year-old breast cancer survivor has pulled off an incredible feat. With some help from French scientists, the woman recently gave birth to a baby conceived from lab matured eggs.

It’s the first time that’s ever been done, and it could open up a whole new world for women looking to preserve their fertility in the face of cancer.

Doctors used in vitro maturation + vitrification together for the first time

Before the unnamed woman started cancer treatment, doctors saw about 17 sacs containing immature eggs in her ovaries. But there was no time to wait for them to mature—doing so could have given her cancer time to spread. So the doctors went into action using a process called in vitro maturation (IVM) to retrieve those eggs and mature them in a lab. Then, they were frozen with a technique called vitrification. It was a risk, however, no cancer patient had ever had a successful pregnancy with an egg that underwent both of those procedures.

Four years after those eggs were retrieved, the patient was ready to have a baby. But after a year of trying on her own, she hadn’t had any luck. Her oncology team didn’t want her to try any new forms of ovarian stimulation so she turned to her frozen eggs. One was implanted and 9 months later, a healthy baby boy named Jules followed. He’s now a year and a half old.

A groundbreaking moment could pave ways for cancer patients to conceive

Professor Michael Grymberg, who worked with the woman from the time she was diagnosed with cancer, said in a statement that the birth was a groundbreaking moment. “We were delighted that the patient became pregnant without any difficulty and successfully delivered a healthy baby at term. My team and I trusted that IVM could work when ovarian stimulation was not feasible.”

Grymberg says he believes fertility preservation should always be offered to young cancer patients, especially now that there’s proof that IVM with vitrification can work. “Our success with Jules shows that this technique should be considered a viable option for female fertility preservation,” he said.

A cancer diagnosis is hard enough, without women having to worry about whether it’ll keep them from ever carrying a child. As scientists continue to break boundaries in the field of fertility—that worry may become less and less relevant.