Using the tools of science to help people make healthy babies is called ART -- for assisted reproductive technology. Here are some of the terms of ART, and the related field of prenatal diagnosis.
AID: Artificial insemination by donor.
AIH: Artificial insemination by husband.
Alpha-fetoprotein screening (AFP): A blood test commonly administered between 16 and 18 weeks of pregnancy. Elevated levels of alpha-fetoprotein in the mother's blood can indicate a neural tube defect such as spina bifida (a spinal column deformity) or anencephaly, the absence of all or part of the brain. AFP screening is controversial because it produces a high rate of false positives: only one or two out of every 50 women with high AFP readings will eventually be shown to have an affected fetus. For this reason, a positive test requires follow-up in the form of amniocentesis or ultrasound.
Amniocentesis: A prenatal genetic test commonly recommended for pregnant women at higher-than-normal risk of having babies with birth defects, including those 35 or older and those with a family history of genetic disorders. Fluid in the amniotic sac surrounding the fetus is extracted and analyzed. The fluid is removed during the 15th or 16th week of pregnancy, and results are usually available within two to four weeks.
Blastomere analysis before implantation (BABI): A test for genetic diseases that involves removing one cell from an embryo and examining it for defective genes. Now used only with in vitro fertilization, BABI may soon be available more generally.
Chorionic villus sampling (CVS): A test for the same genetic defects revealed by amniocentesis that can be performed earlier in pregnancy -- between 9 and 12 weeks. CVS involves removing and analyzing cells from the chorionic villi, tiny hairlike strands of tissue in the placenta that carry the same genes as the fetus.
Fetoscopy: Insertion of a miniaturized photographic instrument into the uterus, usually after the 16th week of pregnancy. Still used only rarely, fetoscopy carries a 3 to 5 percent chance of miscarriage.
Gamete intrafallopian transfer (GIFT): Multiple eggs produced during a hormone-stimulated cycle are removed from the ovaries, mixed with sperm and surgically reinserted in the woman's fallopian tubes. This is the only assisted reproductive technology that has not been specifically condemned by the Roman Catholic Church. It also is one of the most promising of the new technologies, with some clinics reporting a “take-home baby” success rate of over 30 percent, approximately the same as that which occurs in the general population.
Genetic Testing: Determining whether and to what degree a person is at risk of developing or passing on a disease.
Gene Therapy: Repairing or replacing an abnormal gene.
Host uterus (also known as surrogate gestational mother): A woman has her eggs fertilized in a laboratory dish with her husband's sperm, and the resulting embryo is transferred to another woman who will carry the pregnancy to term and then give the baby to its genetic parents.
Intracytoplasmic sperm injection (ICSI): A form of in vitro fertilization that involves propelling a single sperm to the center of an egg.
In vitro fertilization (IVF): Eggs are removed from the ovaries and mixed with sperm in vitro (within glass) in the laboratory. Resulting embryos are transferred to the uterus. It is often but not always accompanied by hormone treatments to produce multiple eggs for fertilization.
Peritoneal ovum sperm transfer (POST): Process similar to GIFT (see above), except that the eggs and sperm are placed just outside the opening of the fallopian tube rather than inside.
Subzonal insertion (SUZI): A form of IVF in which a needle is used to puncture the outer shell of the egg and inject sperm.
Ultrasound or sonography: Through the use of sound waves, ultrasound provides a moving image of the fetus on a small black-and- white screen. It allows doctors to measure the fetus to determine fetal age, examine the position and condition of the placenta and determine the number of fetuses present. It is also used to insure the needle used to remove amniotic fluid for amniocentesis does not touch the fetus.
Zygote intrafallopian transfer (ZIFT): Eggs are removed from the ovaries and fertilized with sperm in a laboratory dish. Resulting embryos are surgically transferred to a woman's fallopian tubes. It differs from GIFT (see above) in that fertilization occurs in the lab, not in the fallopian tube, and from IVF (see above) in that embryos are transferred to the fallopian tubes rather than the uterus.