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To Test or Not to Test: Prenatal Screening

Updated: Nov 8, 2020

I was having some second thoughts on our up-coming IVF. My husband was 100% for testing the embryos before implantation. But I am feeling eager and anxious, and just want to get pregnant as soon as we can, so I went ahead and asked if my doctor could change the protocol to have a fresh transfer.

The difference between the fresh and frozen embryo transfer, as far as success goes these days, is that our fertility clinic has had a slightly higher success with frozen transfers. The problem with the fresh transfer is that if the fetus is abnormal it carries a higher risk of miscarriage. You can only do genetic testing of embryos that you freeze. From what I gather, the cells have to be sent to an external laboratory for DNA amplification and assessment of the chromosome numbers, taking about three weeks to get the results.

We are planning a big move in the near future hence I don’t want to be waiting to transfer an embryo, so where would that leave us? Potentially transferring an embryo that may not make it to term. The majority of miscarriages occur due to some sort of genetic abnormality. So, if we have a fresh transfer, then we cannot do preimplantation genetic testing for aneuploidy (PGT-A), at least on the fresh transferred embryo.

My husband does not want to take the risk having a baby that would not be born healthy. So we agreed that we would test in utero. There are a few different tests to screen for chromosomal abnormalities. The ones I have been reading about are non-invasive prenatal testing (NIPT), chorionic villus sampling (CVS), and amniocentesis.

When I had my phone consultation with our genetic counsellor, she had mentioned that most couples who have a PGT-A tested embryo do not do amniocentesis, but do NIPT. Ok, so what are these?

Non-invasive just means that they are taking a sample from your blood that can predict the genetic make up of the fetus, or at least somewhat. How does this work? So, we probably already know that the maternal endometrium meshes with the fetal placenta for the exchange of nutrients and waste from metabolism in the fetal cells, via the blood vessels within the blood placental barrier. During this exchange some of the fetal genetic materials are sent into the mother’s vascular system that doctors can access through a blood sample from the mother without damaging the fetus. Cool! Obviously, there are limitations of what information you can get from this, both false negative and false positive results, or no results at all. But, it is a simple test, so why wouldn’t you do this?

I guess regardless of these results, if you want to be prepared for a baby with a disability or if you wish to terminate a pregnancy that would result in poor quality of life, however you personally define that, then you may go on to doing CVS or amniocentesis. Many women elect not to test, because the love for your child is not diminished by their disability, however from the father’s perspective things would be different, and I respect that, hence why we have agreed to test.

This study compared CVS and amniocentesis demonstrating that there was no increase in miscarriage for CVS over amniocentesis - though previously it was more risky to sample during early pregnancy (prior to 15 weeks). An abortion of an abnormal embryo is legal in Canada, just a slight side note.

A friend of a friend was pregnant, visibly, then suddenly wasn’t. There is no one in their right mind that would dare to ask what happened, because you risk causing the mother anguish. You still wonder though. What happened?? I thought they were pregnant? Did they miscarry? How sad! Only those women who are brave will be open about the cause of their miscarriage or abortion. I am on enough of these social media groups to understand the social judgement that women place on other women.

Whatever your religious or social background is, it is your decision. In Canada, we are soooo fortunate that so many folks are pro-choice for the mother. It baffles me that still in 2020 the U.S. has state authority over whether a women can terminate a pregnancy!

Abortion Laws in the U.S.

I realize this is a complete aside, but I know that during the current U.S. presidential period, I would check which states were actually deemed illegal, a.k.a. a criminal offence where the mother can be charged or imprisoned. Yikes!

Canadians, consider yourself lucky.

In the early 1970’s, following the second wave of feminism or women's liberation, the U.S. Supreme Court decided during the conclusion of the Roe vs Wade trial that women in the U.S. have a right to choose whether or not to have an abortion, without excessive restrictions from their state government. Where the state gets involved is the rules by which a women can have an abortion.

Of course, with COVID-19, our politicians have been busy, but you can see what the restrictions are for each state here.

Interestingly enough, Harvard is offering a free course on the ethics of ART (assisted reproductive technologies). I'll keep you posted if I have time to take it!

Back to Canada

Saying back to Canada, is kind of like saying, ok, back to be logical and realistic. Oh I kid. Canada basically says that the woman has a right for personal freedom, and can terminate a pregnancy at any stage. So if the fetus is deemed genetically abnormal, i.e. trisomy 18 or 21, then a woman can elect to terminal the pregnancy, even after the first trimester has completed - would she want to? Well, that's up to her to decide.

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