The selective reduction of embryos in multiple pregnancies poses numerous medical, technical, ethical and psycho-social problems. In a retrospective study, we analysed nine hundred and twenty-two pregnancies obtained using medically assisted procreation between May 1982 and May 1990. Among 922 successful pregnancies, 372 were singleton, 102 were twin and 13 were triplet. Data from this analysis and from a French multicentre study of 262 embryo reduction procedures demonstrated the value of an embryo quality score for minimizing the risk of multiple pregnancy and the existence of extremely infrequent, ethically acceptable indications for embryo reduction. These indications included ultrasound-proven malformations of one fetus, multiple pregnancies in patients with extensive uterine scarring, and multiple pregnancy despite the appropriate use of preventative measures which can be expected to make this technique unnecessary in the future.
PIP: This review of the medical and ethical indications and techniques of embryo reduction in multiple pregnancy induced by ovulation induction, in vitro fertilization, or embryo transfer, discusses incidence, consequences, and prevention of high-order multiple pregnancies. Also presented were an analysis of results of 922 pregnancies and a French multicentre study of 262 embryo reduction procedures where an embryo quality score was employed. The incidence of multiple pregnancies in ovarian stimulation ranges from 11 to 44%. In the authors' series of 922 pregnancies followed between May 1982 and May 1990 there were 20% twins and 3% triplets. Triplets were more common after cocyte donation and embryo transfer. Embryo reductions can be done transcervically, transabdominally, or transuterine under endovaginal echo control, which is the safest method. All selective embryo reductions reduce somewhat the risk of premature threatened labor, prematurity and perinatal mortality that would result in higher order multiple pregnancies. A retrospective study of 372 singleton, 102 twin, and 13 triplet pregnancies suggested that the only way to prevent multiple pregnancies is to control the dose of hCG used and the number of embryos transferred. Another approach is to use an embryo quality score based on anatomic uniformity of the embryos transferred. The optimum is to transfer 2 embryos with a total score of 16 or 3 with a score of 16-22. For ovarian stimulation, the number of follicles 10 mm or the estradiol level can be followed. A survey of embryo reduction procedures done in France found that most were done after ovulation induction and for 3, 4, or more fetuses. Other controversial indications for reduction procedures are chromosomal abnormalities and fetal malformations.