A baby has been born through a new technique to "reawaken" the ovaries of women who had a very early menopause.
Doctors in the US and Japan developed the technique to remove the ovaries, activate them in the laboratory and re-implant fragments of ovarian tissue.
The findings have been described as early, but a "potential game-changer" by study lead Prof Aaron Hsueh from Stanford University.
The 27 women involved in the study became infertile around the age of 30 due to 'primary ovarian insufficiency'. The condition affects one in 100 women who essentially run out of eggs too young, leading to an early menopause.
Women have a fixed number of eggs at birth and those with the condition tend to use them up too quickly or are born with far fewer eggs in the first place.
Eggs in the ovaries are not fully formed; rather, they stay as follicles and some mature each month.
The teams at Stanford University, US, and St Marianna University School of Medicine, Japan, were trying to activate the last few remaining follicles, which may be present.
They removed the ovaries from the women and used a combination of two techniques to wake up the sleeping follicles. First they cut the ovaries into fragments, which has been used in the past as a fertility treatment. Then a chemical to "take the brakes off" egg development was applied.
The fragments were put back at the top of the fallopian tubes and the women were given hormone therapy.
Following the treatment, residual follicles started to develop in eight women. Eggs were taken for normal IVF and so far one couple has had a baby and another woman is pregnant.
Prof Hsueh did urge caution around the findings. "It has to be improved to figure out the best way to do it, but we estimate it could help 25 to 30% of the women," he said.
"We think it could help in two other forms of infertility. Cancer survivors after chemotherapy or radiotherapy; if there's any follicles left there's a chance this will help. And also women aged 40 to 45 with an irregular menstrual cycle."