Ask The Experts - Does PGD Improve My Chances?
Q: I am 40 years old and have been experiencing unexplained infertility for about 2 years. I have been reading that PGD may help to improve my chances of success with IVF. Is this true? A: PGD, or Pre-implantation Genetic Diagnosis is a technique, when used in combination with IVF, that can help to determine if the embryos have what it takes to successfully establish a pregnancy. As women get older, there are more errors in the chromosomal make-up of eggs. The most well-known of these defects is Down Syndrome or Trisomy 21, a condition in which the fetus or baby has an extra chromosome number 21. Having a missing or an extra chromosome may make the embryo unable to develop much past a few days of life or may result in a first trimester miscarriage. PGD uses a DNA-binding technique to determine if there are a correct number of chromosomes in the embryo. To do this, embryos on Day 3 of culture (5-10 cells) undergo a biopsy to remove a single cell. The rest of the embryo remains in culture in the IVF laboratory. The biopsy cell is analyzed for the correct number of chromosomes. Currently, PFC with its cytogenetic partner, St. Barnabas Medical Center, tests for 9 chromosome pairs which represent the most common abnormalities seen and some of the most serious in terms of a potential birth defect. As this technology continues to evolve, we expect to be able to assess all 23 pairs. IVF with PGD cannot correct defects in chromosomes. It can only diagnose whether an embryo is abnormal for these 9 chromosomes. The embryo could still be abnormal for one of the other 14 pairs. PGD may decrease the possibility of a miscarriage due to abnormal chromosomes. It may allow for the selection of the embryos most likely to implant and cause a normal pregnancy. If a woman has a good number of fertilized eggs to work with, it may eliminate having an excess number of embryos returned to the uterus at any one time and may eliminate having frozen embryos that really are not genetically normal. Because the embryos will have been screened for some of the major chromosomal abnormalities, theoretically, the remaining embryos should provide a patient who is older a better chance at a viable pregnancy. Some studies have shown that the implantation rates (chance that any one embryo will successfully implant) can be doubled with IVF/PGD. Also, miscarriage rates have been reduced by one-half and the delivered pregnancy rate is increased. Women or couples interested in this procedure should discuss it with their Reproductive Endocrinologist. At PFC, we also refer our PGD patients for a special genetic counseling session in preparation for this process.