Genetic tests like MaterniT21 and Counsyl can be quite expensive. If you got pregnant through IVF and have transferred a PGD/PGS tested embryo, you may wonder if you need to take another genetic test.
I asked this question to my fertility doctor, maternal fetal medicine specialist, and OB. They all agreed that PGS/PGD and MaterniT21/Counsyl essentially test the same thing - genetic abnormalities - at different stages of pregnancy. Genetic information the embryo contained at the time of transfer does NOT change later in pregnancy. So, you do NOT need to take another genetic test later if you have taken a pre-implantation genetic test.
However, it is important that you know what chromosomes your pre-implantation test examined, and post-implantation tests you plan to take will examine. For instance, certain pre-implantation tests only examine a certain set of chromosomes, while other pre-implantation tests analyze all sets of chromosomes.
Similarly, MaterniT21/Counsyl can test only a part or all of the chromosomes. Normally what insurance companies cover is the most basic test, which tests only a part of the chromosomes.
If you have done a full, pre-implantation analysis of chromosomes, there really isn't a need for another genetic test later. However, none of these tests are 100% accurate (they are 95-99% accurate), so if you want to repeat the test for peace of mind, you can certainly do so (and I did).
On the other hand, if your pre-implantation test examined only a subset of chromosomes, it may not be a bad idea to run a fuller analysis of chromosomes later in pregnancy. You'd need to opt for a more advanced version of MaterniT21/Counsyl. Usually, insurance covers only the most basic version, however, if you have paid for a pre-implantation genetic test, you will find the cost of post-implantation tests much more affordable : )