Why does PGD not increase pregnancy rate and does not reduce miscarriages?
No one knows the exact answer, but it is most likely due to eliminating some good embryos through diagnostic errors, mosaicism, damage to the embryo and individual embryo culture. Diagnostic errors PGD for more than 3 chromosomes is not very accurate with one study reporting a 40% error rate using probes for 5 chromosomes. This means that 40% of good embryos could have been discarded due to the errors where an embryo appears to have a missing or extra chromosome, where they are in fact normal. This would reduce a patient’s chances to get pregnant. Most centers report smaller rates of false positive results. Yet, it would be true for every PGD laboratory that each additional chromosome included into the testing increases the chance of error thereby decreasing the chance of pregnancy. This is mainly because each chromosomal probe requires unique optimal conditions for FISH and this is not achievable when they are applied simultaneously. Also, increasing the number of probes results in mo
