The major source of human embryonic stem cells to date has been excess IVF embryos that are donated by couples who have completed their treatment for infertility. In cases in which female patients cannot produce their own eggs, these embryos are made using donated eggs from other women. If stem cells are to be made by IVF purely for research, however, and not as a part of infertility treatment, this would necessarily require the donation of eggs. To make stem cells by nuclear transfer would also require the donation of eggs. So research on human embryonic stem cells may eventually demand a supply of eggs that are donated by women for research purposes.
Over the past two decades, millions of women have had oocytes collected for the purpose of assisted reproduction. Most of those women were IVF patients whose eggs were viable but who were unable to achieve a pregnancy for some other reason, such as blocked fallopian tubes or a partner with a low sperm count. But a significant minority of the women having their eggs harvested were not themselves trying to get pregnant but rather were donating their eggs to help another woman get pregnant.
In 2003, the latest year for which statistics are available, the Society for Assisted Reproductive Technology reported that there were 115,392 assisted reproduction cycles, or attempts, at 428 clinics around the United States. Of those, nearly 12 percent—or about 13,000 assisted reproduction cycles—involved oocytes provided by egg donors.
Whether a woman’s eggs are to be harvested for her own infertility treatment or for donation to another woman—or for research—the donation process is the same. The woman self-injects hormones (gonadotropins) to stimulate the growth of ovarian follicles, plus a gonadotropin-releasing hormone (GnRH) agonist to block the normal surge of luteinizing hormone (LH), which could cause the woman to ovulate before the physician retrieves the eggs. In many instances, GnRH agonists are administered a week before stimulation to control the stimulation cycle and avoid a spontaneous LH surge. A woman subsequently self-injects the hormone human chorionic gonadotropin (hCG, similar to LH) to effect egg maturation. When the eggs are ready, the woman is brought into surgery, where she receives intravenous sedation, after which a transvaginal probe is placed in her vagina. A hollow needle emerges from the probe,