A safer means of stimulating ovulation in women undergoing in vitro fertilization (IVF) with hormones has been developed by scientists in the United Kingdom.

Already, a dozen babies have been born to mothers who received an injection of the natural hormone kisspeptin, rather than the hCG (human chorionic gonadotropin) normally used to stimulate eggs to maturity, researchers from Imperial College London and colleagues reported Saturday in the Journal of Clinical Investigation.

Scientists recently discovered kisspeptins as a class of naturally occurring hypothalamic peptides required for human fertilization. In some women, a genetic inactivation of the hormone’s signaling pathway prevents puberty and renders the body infertile, whereas those with genetic overactivation undergo early puberty. To treat fertility problems arising from too little of the hormone, IVF clinicians typically attempt to stimulate ovulation using hormone treatments. Yet, ovarian hyperstimulation syndrome (OHHS) affects about a third of women receiving the treatments, which may cause nausea and vomiting, while fewer than 10 percent experience more severe reactions potentially leading to kidney failure.

Now, researchers led by Waljit Dhillo think they’ve got an answer. "OHSS is a major medical problem,” he said in a statement. “It can be fatal in severe cases and it occurs in women undergoing IVF treatment who are otherwise very healthy. We really need more effective natural triggers for egg maturation during IVF treatment, and the results of this trial are very promising."

Thousands of women across the UK, U.S., and other developed countries seek IVF treatment every year, although infertility rates have actually declined among U.S. women according to the Centers for Disease Control and Prevention (CDC). Infertility among married women trying to conceive fell from 8.5 percent to 6 percent between 1982 and 2010, according to Georgetown University researcher Anjani Chandra, whose study was released by CDC last year. Yet, even as the U.S. infertility rate continues a decades-long decline, more women continue to seek IVF treatment after delaying motherhood past their prime childbearing years, well into their 30s and 40s.

In the London study, the new hormone treatment helped produce mature eggs in 51 of 53 women, with 49 women undergoing transplantation of one or two eggs to the uterus. "Our study has shown that kisspeptin can be used as a physiological trigger for egg maturation in IVF therapy," Dhillo said. "It's been a joy to see 12 healthy babies born using this approach. We will now be doing more studies to test whether kisspeptin reduces the risk of OHSS in women who are most prone to developing it, with a view to improving the safety of IVF therapy."

The research team now plans to conduct a second study in women with polycystic ovary syndrome, who have the highest risk of OHSS.

Source: Jayasena C, Abbara A, Comninos A, et al. Kisspeptin-54 triggers egg maturation in women undergoing in vitro fertilization. Journal of Clinical Investigation. 2014.