Assisted Reproductive Technology (ART): What Is It and When Is It Used?
Assisted reproductive technology refers to all treatments for infertility during which both sperm and eggs are handled. This is the definition of ART used by the Centers for Disease Control (CDC). It usually refers to procedures in which a woman’s ovaries are stimulated to produce eggs. The eggs are then surgically removed and sperm are combined with the eggs in a laboratory. If an egg is fertilized, an embryo can be introduced into a woman’s uterus.
There has been 20 years worth of experience with ART in the United States. It is estimated that approximately one percent of babies born in the U.S. today were conceived via ART.
In vitro fertilization (IVF) is the best-known procedure. In 1978 the first successful pregnancy following IVF occurred. Children conceived in this way were called “test tube babies.”
IVF is commonly use for female infertility. It can also be used to treat male infertility if the quality of the sperm is adequate. The ovaries are stimulated with injections of a number of hormones during a menstrual cycle so that many are available to be removed (see TREATMENT OF INFERTILITY: OVARIAN STIMULATION). The eggs are then removed through the vagina.
Cells surrounding each egg are removed and are prepared for fertilization. Semen is collected and the sperm are washed and prepared. This makes them more likely to be able to fertilize an egg. Sperm and egg are put together, not in a test tube but in a culture dish. There are usually approximately 75,000 sperm for each egg. In less than a day, the egg will hopefully be fertilized, and the beginning of two cells will be seen. This egg will then be put into another special solution. After growing for about two days, there will now be a tiny, early embryo of 6 to 8 cells. In some places, this size embryo will be used. However, in the United States and Canada, the embryo may grow in the culture medium a little longer, around 5 days. This age and size of embryo, called a blastocyst, can be transferred with a possibly higher rate of successful pregnancy.
There may be a number of eggs and then embryos from one ovarian cycle. The best embryos will be chosen. This is an area where there is active research and room for improvement. There is some genetic screening that can be done, but there is not yet the knowledge necessary to ensure that the embryo will develop into a normal fetus and eventually an infant. There are many factors involved with embryo selection. It depends on the woman’s health, what the reproductive problem is, her age, the doctor’s experience, and other criteria. There are not supposed to be too many embryos used at one time, because of the risk of multiple fetuses. There are regulations in many countries. It is up to the doctor how many embryos to transfer.
If you have been following the case of the Octomom, you know that she had eight children. It has been said that 12 embryos were implanted. This is very clearly in violation of the best medical practices and put both the mother and all the infants, who were born extremely prematurely, at risk. The stated goal of most reproductive specialists is to achieve a single pregnancy with IVF. That is the safest for the mother and the baby. However, at least two to three embryos are usually transferred because there is no guarantee that one will take. The whole process is both difficult and expensive. Time is also passing, which decreases a woman’s fertility. So the risk of multiple pregnancies has to be balanced against the risk of no successful pregnancy.
Carrying multiple fetuses increases the risk of pregnancy for the mother. Multiple fetuses are usually born prematurely and have many medical and developmental complications because of prematurity. Higher multiple pregnancies increase the risk; the more fetuses, the greater the risk. This is clearly a risk of IVF. It is also a risk when ovarian stimulation is used with IUI.
The embryos are usually placed into the uterus through the cervix. To be successful, the embryo must implant into the uterus and begin to grow. The pregnancy rate, in some studies of IVF, has been about 35%. The live birth rate, a better way to judge actual success, is about 27%. However, there is a much higher success rate in certain groups of women. For example, the live birth rate for young women (under age 35) who are having IVF with their own eggs can be as high as 41% per cycle.
There is another ART used specifically for male infertility, when the sperm quality may not be as good. It is called intracytoplasmic sperm injection (ICSI). In this procedure, under a microscope, a single sperm is injected into a single egg. The egg is placed in cell culture material and observed to see if fertilization has taken place, which would then lead to the development of an embryo. After that, the procedure is similar to IVF.
There are an increased number of genetic disorders in infants conceived by both IVF and ICSI. It is not known at the current time if that is because of the procedures themselves, or because of defects in the eggs or sperm that are related to a couple’s infertility.