Doctors at a fertility clinic in Greece have pioneered a technique that might enable pregnancy after menopause.

The doctors have adapted a treatment currently popular in healing sports injuries that affect ligaments, tendons and joints and applied it to rejuvenating women’s reproductive systems. The method involves spinning a sample of a patient’s blood in a centrifuge in order to isolate platelet-rich plasma, which has high levels of the cell fragments related to healing and blood clotting. The clinic then injects this plasma into the ovaries and uterus.

Two women have become pregnant after undergoing this fertility treatment, one a German who previously underwent six unsuccessful IVF attempts and was advised to consider egg donation. After the treatment at the clinic, she tried IVF treatment for the seventh time and became pregnant. The other woman, from the Netherlands, had not menstruated in four years; following the treatment, she not only menstruated, but became pregnant as well. While unfortunately, she miscarried five months into her pregnancy, the menstruation and pregnancy are still encouraging signs, said Kostantinos Sfakianoudis, a gynaecologist with the clinic, speaking with New Scientist.

The technique is far from proven — only 11 of 27 menopausal or peri-menopausal women, aged 34 to 51, experienced a reversal of menopause, with hormone levels returning to their previous numbers, and menstrual cycles resuming – and the clinic is planning a clinical trial to determine if the treatment works by comparing its effects with the effects of placebos.

A clinical trial would also provide clarity around how the treatment works; experts are currently at odds over the theory behind it. While the treatment is based on the assumption that the plasma awakens ovarian stem cells, thus stimulating egg production, the scientific community is undecided whether ovarian stem cells actually exist. If they don’t, it’s possible that the plasma itself contains rejuvenating stem cells. Still other experts have posited that the mere act of injection may have stimulated the ovaries of the women.

Doctors are calling for more and more rigorous research, and ethicists are joining the conversation to discuss the ethics of age and new motherhood. While nothing is clear yet, if nothing else, the treatment has rejuvenated hope for women who may have written off motherhood after experiencing premature menopause.