There is no guarantee for the treatment to be successful. Sometimes, when the egg cells are maturing, the organism sends its own hormones out against them, and the therapy must be interrupted in the cycle. There is also the rare possibility that there are no egg cells at all at the oocyte pickup. The fertilization process itself cannot be influenced. Sometimes egg and sperm cells just don’t unite. The embryo can’t be forced into embedding itself into the uterus lining, even after medication has been given to enhance the chances.
The success rates of in vitro fertilization and embryo transfer are to be judged individually. When the hormone and sperm tests are normal and the procedure is carried out in a professional centre, applied to all patients (with in vitro fertilization indication, respectively ICSI, diseased Fallopian tubes or poor sperm tests), and with the customary culture technique up to day 2 – max. day 3 after the pickup - the success rate is between 25% and 37% per pickup. (P. Vanderzwalmen, H Zech et.al: Human Reproduction. 12:1203, 1997; H. Zech, A.Stecher et.al: Journal for Fertility and Reproduction. 7:15, 1997).
Completely different success rates must be taken into consideration when the criteria vary (age of the woman, reason for therapy and culture technique up to the blastocyst stage). The women with the best chances are those under 30yrs. of age with a good reaction to the follicle stimulation (more than 10 egg cells per pick up) and transfer from blastocysts--in these cases 70% of the pregnancy tests are positive.
The situation becomes more difficult, the older the woman gets: respectively over 40yrs. With optimal preparation and good follicle development, there is only a 5% chance that a woman between 43yrs. and 45yrs. will have an intact pregnancy.
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