Scientists believe that some cases of infertility might be treated by injections of a hormone.
One in nine couples experience fertility problems
A team at London's Hammersmith Hospital has shown that shots of the hormone kisspeptin stimulate the release of the hormones that control periods.
Kisspeptin has already been identified as the genetic switch that turns on puberty. Humans that lack the hormone remain sexually immature.
The findings are being presented to a Society for Endocrinology conference.
Production of kisspeptin is controlled by a single gene, dubbed KiSS-1, by researchers in Hershey, Pennsylvania, who named it after the town's most famous type of chocolate bar.
The Hammersmith Hospital team wanted to see what effect the hormone would have on a woman's ovulation.
To check its safety, they injected small doses into six healthy female volunteers and monitored its effect.
After the injection the volunteers showed a rise in their circulating concentrations of luteinising hormone (LH), a hormone which is needed to cause ovulation.
Kisspeptin increased LH concentrations at all stages of the menstrual cycle, but the effect was greatest in the pre-ovulation phase.
Dr Waljit Dhillo, who led the research, said: "Kisspeptin has previously been shown to potently stimulate hormone release in animals, but this is the first time that it has been shown to stimulate sex hormone release in women.
"We might now look at giving this hormone to women who have no periods, those with irregular cycles or who have a period but do not ovulate.
"One in nine couples are affected by infertility, and this could be one of the treatments."
Dr Simon Fishel, director of the Care Fertility Group, said: "This is not surprising, because of what we know about kisspeptin already, but it is interesting that they have found these results in women.
"It had to be tried first in healthy women to show it was tolerated, and that it works.
"Researchers will now have to see if it has future potential as a treatment."