There are various problems that are directly associated with in vitro fertilization in the process known as assisted reproduction, and these in turn, may be the result of a stimulation of ovaries, or pregnancy. Ovarian hyperstimulation syndrome, arises in the last phase of the menstrual cycle and refers to an abnormally high ovarian response to hormonal stimulation, and that furthermore remains persistent over a considerable period of time. This syndrome is a complication for ovarian stimulation in assisted reproduction hormone treatments. Multiple pregnancies on the other hand, occur in cycles where two embryos are transferred. In this way, the probability of having a twin pregnancy is 6%. In cycles where three embryos are transferred the probability of having a twin pregnancy is 12% while having a triple pregnancy is 3%.
A multiple pregnancy has significant health risks both for the mother and for hatchlings, and usually ends in a premature birth. As pregnancy risk highlights the natural abortion estimated that it occurs in approximately 20% of cases, while that pregnancy ectopic it may suffer from between 2 and 5 women undergoing in vitro fertilization 100..