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In Vitro Fertilization

Laboratory procedure in which an egg is fertilized by sperm in a specimen dish outside the woman's body.

In vitro fertilization (IVF) is a medical procedure that combines a human egg (ovum) and sperm in a laboratory dish to increase the possibility of conception. Two days after successful fertilization, the fertilized egg or embryo is placed in the woman's uterus, where it remains for a normal pregnancy and birth. Louise Brown became the first "test-tube baby" conceived using this procedure when she was born in England on July 25, 1978. Since then about 100,000 successful births have resulted from in vitro fertilization, but the procedure still has a relatively low success rate. When measured by the number of pregnancies achieved by the number of egg retrieval attempts, the overall IVF success in the United States is about 18%. (In other words, 18 pregnancies can be expected from 100 attempted egg retrievals.)

The procedure

In vitro fertilization consists of four distinct steps. In the first step, the woman receives daily injected doses of hormones to stimulate the ovaries to produce multiple eggs. The effect of the hormone doses on maturation of the eggs is monitored closely for about two weeks by the fertility clinic through blood tests and ultrasound tests of the ovaries. If the woman's body has responded by producing several mature eggs, she and her partner prepare for the next step: removal of the eggs from the ovary. (Research has shown that the success rate of in vitro fertilization can be improved by fertilizing three or four eggs. A woman's normal monthly cycle produces just one egg.)

Exactly 36 hours before egg retrieval, the woman receives an injection of the hormone human chorionic gonadotropin (HCG) to prepare her body for pregnancy. Following egg retrieval, she will receive daily injections of progesterone for about two weeks to further prepare her uterus for pregnancy. The egg retrieval takes place in the clinic. Ultrasound is used to guide a thin, hollow needle into the vagina, through the vaginal wall, and into the ovary. The eggs are sucked, one by one, into the needle.

The next step in the IVF process is fertilization of the eggs in the laboratory. A few hours before egg retrieval, the woman's partner provides the lab with a semen sample. The sperm and eggs are placed together in a laboratory dish.

The final step is the transfer of embyos into the woman's uterus. Two days after retrieval, the eggs are checked for evidence of fertilization. Three or four embryos are transferred into the woman's uterus. Although it is unlikely that all the embryos will survive, twins and triplets occur in about one-third of in vitro fertilization pregnancies. If more than that number of eggs have been successfully fertilized, the couple, together with their doctor, must decide whether to freeze the extra embryos, discard them, make them available for research, or donate them to another infertile couple. Most couples elect to freeze their embryos with the intention of using them in future pregnancy attempts.

In two weeks, a pregnancy test will show whether IVF has been successful. If it has, the couple prepares for a pregnancy that is subject to the same risks of miscarriage and birth defects as any pregnancy. If IVF has failed, the couple may choose to repeat the procedure. Most clinics discourage repeating IVF more than four times.

Couples electing IVF know that the odds are against them, and that the procedure is costly, both financially and emotionally. In the mid-1990s, the cost of an IVF procedure was estimated to be $7,500 to $10,000. In many cases, health insurance will not cover this procedure. Physically, the woman must be prepared for some discomfort and the possibility of serious side effects from the massive hormone doses. Both the woman and the man can expect to have their ordinary work and home lives disrupted by the IVF regimen. To help couples cope psychologically, many clinics have therapists on staff. Despite these challenges, about 40,000 infertile couples invest millions of dollars in IVF each year.

Ethical issues

Since 1978, IVF has gained acceptance among physicians, the public, and all major religious groups, and is no longer considered an experimental medical procedure. Troubling ethical issues arise, however, when multiple embryos are produced.

Almost all couples elect to freeze extra embryos. As of the mid-1990s, tens of thousands of frozen embryos existed in the United States alone. Ideally, the couple decides in advance what to do with the embryos in the event of death or divorce. In a few well-publicized cases, however, couples have fought for "custody" of the embryos. The existence of frozen embryos is also troubling for those who believe that these tiny beings deserve some consideration as potential humans. Additionally, it is not uncommon for the couple who elected to store the embryos to lose contact with the clinic once they have completed their fertility treatment. In 1991, a law was passed in the United Kingdom placing a five-year time limit on storage of frozen embyos. Under this law, 3,300 fertilized human eggs were disposed of, having reached their time limit in August 1996.

Multiple embryos transferred into a woman's body, if most or all survive, also force a difficult decision. Carrying more than twins greatly increases the odds of a difficult pregnancy and premature birth. To prevent such outcomes, physicians encourage women carrying three or more fetuses to consider fetal reduction, also known as selective termination. In this procedure, excess fetuses are aborted with a chemical injection. Fetal reduction is usually done prior to the third month of pregnancy.

New scientific breakthroughs involving IVF continue to pose ethical questions. It is possible for an egg donated by one woman to be fertilized by an infertile woman's husband's sperm and implanted into the infertile woman. This procedure challenges common notions of motherhood. Is the mother the woman who gave birth or the woman who contributed the egg? Couples and the health care community will continue to struggle to balance the couple's desire for parenthood with the developing technologies, costs, and ethical issues of fertility treatments.

For Further Study

Books

Silber, Sherman J. How to Get Pregnant with the New Technology. New York: Warner Books, 1991.

Periodicals

Adler, Jerry. "Clone Hype." Newsweek, November 8, 1993, p. 60.

Gibbs, Wayt, and Tim Beardsley. "Fertile Ground: IVF Researchers Pioneer the Bioethical Frontier." Scientific American, February 1994, p. 26.

Grady, Denise. "How to Coax New Life." Time Special Issue: Frontiers of Medicine 148, no. 14, Fall 1996, p. 36.

Hopkins, Ellen. "Tales From the Baby Factory." New York Times Magazine, March 15, 1992, p. 40.

Lemonick, Michael D. "Sorry, Your Time Is Up: A Controversial British Law Targets 3,000 Human Embryos for Disposal." Time 148, no. 8, August 12, 1996, p. 4L