A hormone made by a gene called "kiss" has the potential to restore fertility in some women, scientists have found.
Twice weekly injections of the natural drug lead to long-term increases in levels of sex hormones that control the menstrual cycle, a study showed.
The findings suggest a new way to treat women whose infertility is due to low sex hormones.
Kiss-1 is a gene that plays a key role in regulating reproduction. It produces the hormone kisspeptin, which helps humans and other animals go through puberty and become sexually mature.