The researchers of the universities of Bristol and Glasgow, led by Andrew Smith, who They made after publication in the Journal of the American Medical Association (JAMA), according to the "New York Times", examined data on nearly 157,000 women, which together made more than 257,000 "circles" IVF. A "cycle" is considered the hormone hyperactivation of the ovaries to produce several eggs, IVF and subsequent embryo transfer to the uterus. Statistical analysis shows that successful delivery of the first process is achieved in 29.5% of cases. 20.5% of women give birth child with the fourth attempt, 17.4% the sixth and 15.7% in the ninth. Thus, at least two in three women (67.4% rate) become successful in vitro to their sixth attempt. Often women are disappointed after the third or fourth failed attempt, but new research -the largest of its kind until today It shows that there is still considerable success margins IVF, especially for women under 40 years, which need not be frustrated prematurely and turning to alternatives like eggs from another woman or teknothesia. The woman's age plays an important roll. Before the 40s, success at the first attempt is 32.3% of women and the sixth 17%. For women 40-42 years old, the respective success rates are 12% and 6.9%. But after the ninth attempt, chances are now very small. On the other hand, the repeated attempts (cycles) are a financial and emotional burden for many infertile couples, and without neglecting the potential medical risk because of the burden of the ovaries.