by Lori Arnold, MD
For the 6.1 million American women and their partners who are affected by infertility, the dream of having a successful pregnancy may seem unattainable.
Fortunately, fertility treatments have made baby dreams into realities for millions of people, and promising new advancements in reproductive medicine are paving the way for even higher success rates and lower risks.
With in vitro fertilization (IVF), embryos are grown outside of a woman’s body and implanted several days later into the uterus with the goal of achieving a successful pregnancy. Until the last decade or so, however, we had no way of knowing whether an embryo might have a defective chromosome that could lead to Down syndrome or another birth defect.
Preimplantation genetic diagnosis (PGD) enables us to identify potential problems with an embryo before it is implanted.
PGD involves taking a biopsy of the embryo on day 3 of its development and examining the chromosomes through a procedure known as fluorescent in situ hybridization (FISH), which utilizes fluorescently labeled DNA probes to identify abnormalities.
Though we are not yet able to apply FISH to all 22 chromosomes, we can look at those which are most often associated with a problem. By testing chromosome 21, for example, we can determine whether an embryo will develop Down Syndrome.
An abnormality in chromosome 18 may indicate Edward’s Syndrome, a serious disorder of the heart, lungs and digestive system. While PGD was first used as early as 1990 to detect cystic fibrosis, the technology has only recently been applied to the chromosomes, and now extends to more than 30 different types of genetic diseases, including Tay-Sachs disease, cystic fibrosis and muscular dystrophy.
PGD has been a significant breakthrough for reducing miscarriages, especially in women of advanced maternal age. We know that up to 70 percent of embryos in women over the age of 40 will have a genetic abnormality, and 25 to 40 percent of women in this age group will miscarry as a result.
PGD gives us the tools to screen for these abnormalities and implant only those embryos that are genetically normal, thus greatly decreasing the risk of miscarriage.
The older a woman is, the higher the risk that her eggs will develop genetic abnormalities. Egg freezing is a very new procedure that enables women to have their eggs frozen until they are ready to become pregnant, thus preserving the eggs before they can develop additional genetic defects.
The frozen eggs are thawed, fertilized with sperm and implanted. Egg freezing was first done successfully in Bologna, Italy in 1988 and has since resulted in approximately 100 healthy births worldwide; however, is still considered experimental.
In a natural pregnancy, the embryo travels down the fallopian tube into the uterus on about day 4 or 5 of its development. It becomes what is known as a blastocyst and implants into the uterus on day 6.
Reproductive technology has become so evolved that we can now grow embryos into the blastocyst stage and, using ultrasound, determine exactly where to transfer the embryo into the uterus. Since we began using this technology, our success rates have doubled.
Advancements in reproductive medicine have also enabled us to overcome physical complications once thought to make pregnancy impossible. In men, such obstacles may include vasectomies, very low sperm counts or blockages that prevent the release of sperm.
By surgically removing sperm from the testicular area and injecting it into the egg, we can create embryos which can then be implanted.
Similarly, women who have blocked fallopian tubes or tubal problems may produce a fluid that can be toxic to a developing fetus. We have found that removing these blocked tubes before proceeding with IVF can greatly improve the chances of both conceiving and avoiding miscarriage, and it is now the standard of care in such cases.
Clearly, this is an exciting time in reproductive medicine, and new developments in research and technology promise even more advancements in achieving safe, healthy pregnancies.
This Scripps Health and Wellness tip was provided by Dr. Lori Arnold, an OB/GYN with Scripps Memorial Hospital La Jolla.