Preimplantation genetic screening-PGS- tests embryos for normal chromosome numbers. Does this testing improve IVF success rates and if so, who is this testing for?
The answer is "yes" it does improve IVF success rates and we feel PGS should be offered to all couples undergoing advanced reproductive technologies!
Mistakenly, PGS is thought to be only for those couples where the woman is of advanced reproductive age or who has undergone multiple pregnancy losses or who has had repeated IVF failures. Why limit the offering to just those groups? There is no reason! PGS is now more affordable than ever with genetic labs offering "a la carte" pricing when limited numbers of embryos are tested.
Did you know that 80 % of Down's syndrome babies are born to women under the age of 35? Of course, that is because younger women have more births than women over the age of 35. At age 30, the risk of having a baby born with a Down Syndrome is 1/900, by age 35 the risk is 1/350, but by age 40, that risk is 1/100!
Some may consider PGS an extreme for the younger patient and contend that prenatal genetic testing by cell-free DNA test is a better option BUT that information is AFTER the fact- the pregnancy is now a reality. How accurate is the test? What can it detect? Does it detect all pregnancies with Down syndrome? Cell- free DNA is thought to detect 99% of all Down syndrome pregnancies (trisomy 21), greater than 98% of all trisomy 18 pregnancies, and about 65% of all trisomy 13 pregnancies. When the test result indicates a high risk, further diagnostics such as CVS (chorionic villi sampling) or amniocentesis is used to confirm. If results are validated, the patient then must face whether to continue or terminate the pregnancy. Many obstetricians will not perform terminations and will refer out to "abortion clinics". Not the first choice for most patients. Consider that PGS would have eliminated this scenario altogether!
Studies have shown that up to 50% of embryos from IVF that are screened are chromosomally abnormal. This rate is largely affected by the age of the female. It is fact that the eggs of older women are more prone to chromosomal abnormalities, and although the exact reason is unknown, research has shown that the meiotic spindle that is critical in organizing chromosome pairs, is abnormal in older women. PGS affords the advanced reproductive age patient the advantage of screening embryos before implanted, dramatically reducing the risk of early pregnancy loss.
We have talked a lot about the screening process identifying abnormal embryos but the key factor is that PGS affords us a very high pregnancy rate by implanting a single, genetically tested embryo. Single blastocyst transfer of a normal tested embryo is virtually eliminating multiple births, dramatically reducing obstetrical complications associated with multiples, and will reduce NICU need down to all time lows.