It has made dreams come true for thousands of previously childless couples, and provides a lifeline of hope for many more. It is in-vitro fertilization, a process that has become commonplace within the last several decades.
Today, IVF is in the public eye mostly when multiple births -- such as quadruplets or quintuplets -- result. Still, confusion remains as to how the process works, how often it works and who stands to benefit the most from its possibilities.
For the answers to these questions, I consulted Dr. Anne Namnoum, director of Assisted Reproductive Technology at the Johns Hopkins School of Medicine.
Q: What is in-vitro fertilization?
A: IVF is the process of fertilizing a woman's egg in the laboratory with sperm, then transferring the pre-embryo back to the woman for normal development and eventual birth. Most of these procedures are performed with the assistance of fertility drugs, which can cause multiple eggs to develop simultaneously. Multiple fertilized eggs transferred inside the woman increase the chance that a successful pregnancy will "take."
The fertility drugs are injected in 10-day cycles during critical points in a woman's monthly cycle. The egg(s) then are retrieved from the ovaries and are fertilized. Within two to three days, the pre-embryos are loaded into a catheter and injected into the uterus, or, through laparoscopic or "keyhole" surgery, inserted into the fallopian tubes.
Another method, gamete intrafallopian transfer (GIFT), involves the transfer of both eggs and sperm into the fallopian tubes, where fertilization normally occurs.
Q: Who is a candidate for IVF?
A: Since IVF bypasses the fallopian tubes, the most common candidates are women whose tubes are damaged or obstructed by disease or other causes. Other candidates are women whose tubes may be functioning normally, but whose partners suffer from male-factor infertility -- meaning that sperm count and/or motility (movement) is low. IVF helps these cases by concentrating more sperm around the egg.
A variation of this, for the least motile sperm, is the micro-manipulation technique, in which a single sperm is injected into the egg.
IVF also can be tried in women with no apparent reason for infertility, in whom other, less aggressive therapy has been unsuccessful.
Q: What chance of success should a woman expect?
A: The two biggest factors in success rates are the reason for the procedure and the age of the patient. Generally, women older than age 40 experience less success, due to the declining quality (increased chromosomal problems) of their eggs. Overall, the procedure seems to work about 20 percent of the time per attempt.
Q: How often can the procedure be repeated?
A: The only real limits, provided the patient is in good physical health, are emotional and financial. Repeated disappointments no doubt exact an increasing emotional toll. The average cost of the procedure -- about $8,000 to $10,000 -- also takes a toll. Insurance coverage varies widely, with many insurers placing a limit on the number of IVF attempts they will cover. Some companies do not cover the procedure at all.
Q: Are there complications or risks from IVF?
A: The biggest risk from IVF, when fertility drugs are used, is multiple births (mostly twins), which account for about 30 percent of total births. Of course, the chances of this are reduced by the transfer of fewer fertilized embryos back to the woman. The challenge is to achieve the right "balance" in the number of embryos needed to maximize the chance of pregnancy while minimizing the chance of multiple births.
The intramuscular injection of fertility drugs can lead to temporarily sore hips and thighs. A rare but potentially much more serious condition is ovarian hyperstimulation, in which the ovaries become swollen and fluid can accumulate in the abdomen and lungs. In addition, studies are being conducted to help determine whether fertility drugs increase a woman's risk of ovarian cancer. Although no link has been established, women should be aware of the investigation in this area.
For some women, IVF may be the only way to achieve a much-desired pregnancy.
Future advances may improve the success rates and decrease the risks associated with this and other similar procedures.
Dr. Matanoski is a physician and epidemiologist at the Johns Hopkins School of Hygiene and Public Health. She is founding director of its Institute for Women's Health Research and Policy.