Today, in vitro fertilization (IVF) is practically a household word. But not so long ago, it was a mysterious procedure for infertility that produced what were then known as "test-tube babies." Louise Brown, born in England in 1978, was the first such baby to be conceived outside her mother's womb.
Unlike the simpler process of artificial insemination -- in which sperm is placed in the uterus and conception happens otherwise normally -- IVF involves combining eggs and sperm outside the body in a laboratory. Once an embryo or embryos form, they are then placed in the uterus. IVF is a complex and expensive procedure; only about 5% of couples with infertility seek it out. However, since its introduction in the U.S. in 1981, IVF and other similar techniques have resulted in more than 200,000 babies.
GIFT (gamete intrafallopian transfer) and ZIFT (zygote intrafallopian transfer) are modified versions of in vitro fertilization (IVF).
Like IVF, these procedures involve retrieving an egg from the woman, combining with sperm in a lab then transferring back to her body, but in GIFT and ZIFT the process goes more quickly. While in traditional IVF the embryos are observed and raised in a laboratory for 3 to 5 days, in ZIFT, the fertilized eggs -- at this stage called zygotes -- are placed in the fallopian...