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Genetic Causes of Recurrent Pregnancy Loss
a blog by Joseph A. Hill, III, MD, Fertility Centers of New England, October 12, 2010
Today, there are more options for treating genetic causes of recurrent miscarriage.
There are therapeutic options to treat genetically inherited thrombophilias such as Factor V Leiden or other genetic mutations that increase blood clotting. These therapies include antithombotic medications such as:
- low dose aspirin and
- low molecular weight heparin.
These pregnancies are at high risk for complications later in pregnancy including intrauterine growth restriction and placental abruption. The pregnancies should be followed in consultation with a maternal-fetal medicine specialist as needed.
PGD and PGS for Chromosome Rearrangements
The best treatment for parental chromosome rearrangements such as a balanced translocation, (occurring in 3 percent of couples with recurrent pregnancy loss) is preimplantation genetic diagnosis (PGD).
PGD is a novel therapy that involves analysis of the specific chromosome rearrangement in question. Analysis is performed on a cell biopsied from an early embryo (Day 3 after fertilization) created through in vitro fertilization (IVF).
An alternative therapy for an inborn chromosome abnormality in one of the partners of the recurrent aborting couple would be to use either donor egg or sperm, depending on the affected partner.
Since the majority of early pregnancy losses are chromosomally abnormal, it could be argued that the use of preimplantation genetic screening (PGS) — in which IVF is performed followed by embryo biopsy on Day 3 following fertilization — may be of benefit. To date, there are no studies that have proven the effectiveness of PGS; however, these published studies have not been able to test for all 23 pairs of chromosomes. It is only within the past year that the technology to screen for all 23 pairs of chromosomes has been available.
Currently, it is also possible, should an abnormality be found in the embryo, to determine the origin of the abnormality — whether it is from the sperm, the egg, or de novo (from the embryo itself). A large multicenter trial is currently underway in Europe to determine how effective PGS is for couples suffering reproductive failure.