Science and A.R.T.
Sometimes it may be necessary or preferable to get pregnant without intercourse. A woman may choose to get pregnant with the sperm of someone who is not her partner. In some cases, a woman may not be able to become pregnant with her partner because his sexual problems make it impossible for him to ejaculate normally during sex, or because the sperm have to bypass the vagina if the vaginal mucus cannot support them, or for other reasons. In these cases, through artificial insemination, the semen is placed into the woman’s uterus or vaginal canal using a hollow, flexible tube called a catheter.
New, more complex assisted reproductive technologies, or ART, procedures, including in vitro fertilization (IVF), have been available since the birth 18 years ago of Louise Brown, the world’s first “test tube baby.” IVF makes it possible to combine sperm and eggs in a laboratory for a baby that is genetically related to one or both partners.
IVF is often used when a woman’s fallopian tubes are blocked. First, medication is given to stimulate the ovaries to produce multiple eggs. Once mature, the eggs are suctioned from the ovaries (1) and placed in a laboratory culture dish with the man’s sperm for fertilization (2). The dish is then placed in an incubator (3). About two days later, three to five embryos are transferred to the woman’s uterus (4). If the woman does not become pregnant, she may try again in the next cycle.
Other ART procedures, based on many of the same principles, include:
Gamete intrafallopian transfer, or GIFT: Similar to IVF, but used when the woman has at least one normal fallopian tube. Three to five eggs are placed in the fallopian tube, along with the man’s sperm, for fertilization inside the woman’s body.
Zygote intrafallopian transfer, or ZIFT (also called tubal embryo transfer): A hybrid of IVF and GIFT. The eggs retrieved from the woman’s ovaries are fertilized in the lab and replaced in the fallopian tubes rather than the uterus.
Donor egg IVF: For women who, for example, have impaired ovaries or carry a genetic disease that can be transferred to the offspring. Eggs are donated by another healthy woman and fertilized in the lab with the male partner’s sperm before being transferred to the female partner’s uterus.
Frozen embryos: Excess embryos are frozen, to be thawed in the future if the woman doesn’t get pregnant on the first cycle or wants another baby in the future.
New treatments for male factors are fast-evolving. Intracytoplasmic sperm injection is one of the most exciting new procedures, according to Benjamin Younger, M.D., executive director of the American Society for Reproductive Medicine. A single egg is injected with a single sperm to produce an embryo that can implant and grow in the uterus.
About two-thirds of births from ART procedures are single births. Of the rest, almost all are twins, with about 6 percent resulting in the birth of triplets or more.