ABSTRACT
Multiple pregnancies are the most significant, albeit avoidable, complication of in vitro fertilization (IVF). With increasing worldwide clinical experience, it became obvious that success rates, in terms of clinical pregnancies and ‘take-home’ babies, are highly dependent on the quality of oocytes as determined by maternal age. This reality led to the widespread use of controlled ovarian hyperstimulation to increase ovum pick-up rates, which in turn led to improved fertilization rates based upon a higher number of fertilized eggs-now termed embryos. Unfortunately, when more than a reasonable number of embryos are available for transfer, ethical as well as clinical problems may arise. One is then faced with the option of either discarding or freezing surplus embryos in order to avoid excess embryo transfer (ET) (see Chapter 19). Often, when the number of ETs causes a high-order (triplets or more) multiple pregnancy, multifetal pregnancy reduction (MFPR) is offered (see Chapter 63).
