Some fertility drugs substantially increase the probability of multiple births. [ACOG Technical Bulletin 120. Medical Induction of Ovulation. September 1988.] In vitro fertilization techniques can also result in multiple gestations if more than one embryo is introduced, with a rate of twins of 15% to 18% and of triplets of 1% to 2% with four preembryos. [ACOG Technical Bulletin 140. New Reproductive Technologies. March 1990. [ACOG Technical Bulletin 140. New Reproductive Technologies. March 1990.] Multiple gestation poses grave risks to both the fetuses and the mother. [ACOG Technical Bulletin 120. Medical Induction of Ovulation. September 1988.] These risks should be explained in detail. The woman must understand that the risk is not that she will have twins or triplets (or more) but that one or more of the babies may be severely disabled and that she may suffer medical complications. The physician should also discuss the possibility of pregnancy reduction and selective fetal termination. A woman with multiple gestation must be informed of her options:

1. Abort all fetuses

2. Attempt to carry all fetuses to term

3. Terminate some of the fetuses [ACOG Committee on Ethics, Committee Opinion 94. Multifetal Pregnancy Reduction and Selective Fetal Termination. April 1991.]

The introduction of multiple preembryos is intended to increase the success rate of in vitro fertilization. This benefits the patients by reducing the cost and medical risks of multiple procedures, but it is also critical to the success of the fertility center’s marketing. Few persons would be willing to undergo the risk and expense of in vitro fertilization if the success rate were only 3% to 4%. Physicians have a duty to ensure that patients understand this trade-off between success and the attendant risk of multiple births.

The physician should also discuss the possibility of amniocentesis on the individual fetuses and the termination of those with genetic diseases. This is a dangerous process, however, because it is usually done later in the term, and retained fetal tissue can cause disseminated intravascular coagulation, with fatal consequences for the mother. [Novick LF, et al. New York State HIV Seroprevalence Project, Chapter II Newborn Seroprevalence study: methods and results. Am J Pub Health Supp. 1991;81:15–21.]