What are the advantages of preimplantation genetic diagnosis?
An alternative to prenatal diagnostic testing: Couples avoid the distress associated with diagnosis, particularly if late in an established pregnancy.
An alternative to termination of pregnancy: If prenatal testing (through amniocentesis or chorionic villus tests reveals a genetic abnormality, the options available to parents are to have a child with a genetic condition or to undergo a pregnancy termination. This is a difficult and often traumatic decision. However, PGD is performed before pregnancy begins, thus eliminating this difficult decision.
The opportunity to conceive a pregnancy that is biologically the parents’ own and yet unaffected by a genetic condition in the family: couples for whom the option of prenatal testing and termination is not an acceptable choice may not want to take the risk of a child having a genetic condition. In the past, potential parents with a genetic condition or those who know that they are carriers frequently chose adoption, embryo donation, or surrogacy or chose not to have children in order to avoid the risk of passing on the condition. PGD now allows these couples the opportunity to have a child free of the condition.
Are there risks involved in preimplantation genetic diagnosis?
Risks of treatment
Most of the risks involved in PGD treatment are similar to those for conventional IVF:
- Fertility drug reaction: mild reactions may involve hot flushes, feeling down or irritable, headaches and restlessness; symptoms usually disappear after a short time.
- Multiple pregnancy: risk of complications is higher in a pregnancy with twins or multiples (although some centres reduce this risk by only transferring one embryo).
- Ovarian Hyperstimulation Syndrome (OHSS): Symptoms include abdominal pain and swelling, shortness of breath, nausea, vomiting, and a reduction in urine output; can result in mineral imbalances in the blood and clotting problems.
- Pelvic infection.
- Miscarriage: risk of a miscarriage after IVF is no higher or lower than after a natural conception.
- Ectopic pregnancy: pregnancy development in the fallopian tubes instead of the womb. This would not result in an ongoing pregnancy.
Risks to babies born following PGD
No strong evidence currently exists to suggest that babies conceived through this process are at any greater risk of abnormality than babies conceived through other forms of assisted reproduction.
Several studies have concluded that there do not appear to be any major side-effects to the PGD treatment. However, there is evidence that babies conceived through IVF are more likely to:
- be born prematurely
- weigh less than naturally conceived babies born at the same age
Follow-up data remains limited and long-term outcomes are unknown. It is important to continue to monitor the progress of children born following PGD, to gather information about the potential impact of the treatment.