Ovarian stimulation and monitoring
The best chance for a successful pregnancy is obtained when more than one embryo is placed in the uterus.
This is because so many early human embryos, normally fertilised, do not develop further. Consequently, one way of overcoming this is to put two or more embryos back during IVF. However, when two or three embryos are put back together, the risk of a multiple pregnancy such as twins is greater and is certainly higher than in natural conception. This is an issue that should be discussed with the couple before ivf treatment.
In order to obtain more than one embryo simultaneously, we obviously need more than one egg. This is why drugs are given to make the ovaries work harder than normally. Occasionally many eggs are obtained simultaneously but it is very uncommon for all of them to fertilize and make an embryo. Usually, about 60% of the eggs fertilise normally, and if ICSI is used, up to 90% of the mature oocytes are fertilised.
The drugs to make you ovulate will normally be given to you a few days after your period, at the start of the treatment cycle. We vary the dose and the length of time these drugs are given, depending on your individual response. This usually results in the ovaries responding more effectively to the treatment. More eggs seem to be produced, with a higher pregnancy rate in certain cases. The doctor co-coordinating your treatment will explain this fully.