With new information available, authors of a Cochrane Systematic Review have revised their conclusions about the relative effectiveness of two different treatments used to help women become pregnant. They now conclude that giving women gonadotrophin-releasing hormone (GnRH) antagonists leads to similar live-birth rates compared with GnRH agonists. Previously they had concluded that women who used antagonists tended to have lower birth-rates than those using agonists.
This is important because the systematic review also showed that GnRH antagonists can halve the risk of over-stimulating the ovaries compared with GnRH agonists, as well as halving the number of women who have to pull out of a cycle of therapy.
To help women who are having difficulty becoming pregnant, doctors sometime treat them with hormone mimicking drugs that influence the way that eggs develop in their ovaries. One key danger of this is known as ovarian hyperstimulation syndrome (OHSS), which can be life-threatening for the woman. Previous advice was that women might like to consider using antagonists because they appeared to be safer, but should be counselled that their chance of becoming pregnant was lower.
In 2006, when the researchers reached their earlier conclusion, they were only able to draw data from 27 trials. Since then more research has been published, allowing them to consider the findings of 45 randomised controlled studies that involved a total of 7,511 women. "This increased amount of data lets us get a much better idea of how well the two approaches compare," says Dr Hesham Al-Inany, who was lead author of the research and works at Cairo University, Egypt. Dr Al-Inany led a multi-centre team, with researchers also based in the Netherlands and Canada.
"The reduction in ovarian hyperstimulation combined with a comparable live-birth rate mean justifies a move away from the standard GnRH agonist to using GnRH antagonists," says Dr Al-Inany.