Armchair Chat: Prenatal Screening Advice from a Catholic OB/GYN

Prenatal screening testing has changed a lot since I began my OB/GYN residency in 2004. Initially, we only ordered a “triple screen”, a blood test drawn between 15-18 weeks gestation that looked at three different markers. The triple screen was not able to give a certain diagnosis, but only a probability based on the patient’s age, the gestational age of the pregnancy and the results of the blood test as to whether a certain genetic abnormality might exist. And really it only tested for three possibilities—Trisomy 21 (Down syndrome), Trisomy 13 (Patau’s syndrome) and Trisomy 18 (Edwards’ syndrome). If the pregnancy was dated incorrectly, the results of the triple screen could be listed as abnormal when in fact all was well. I have personal experience with this. A family member was told to abort their child based on the results of a triple screen using an incorrect gestational age. It was only at birth that it was discovered the child in fact did not have any of the health conditions screened for, or any other health issues for that matter.

A few years into my residency, we began using the “quad screen”, which was basically the triple screen with one additional marker. It is supposed to be a more precise probability than the triple screen. However, it is still only a probability and not a definitive diagnosis. Whenever a triple screen or quad screen returned with what was considered a high probability, the next step was always an amniocentesis. With amniocentesis, a needle was placed through the mother’s abdomen, through the uterus and into the water bag surrounding the baby. Fluid is then removed and cells in the fluid cultured to do genetic testing. This would then be considered definitive proof as to whether the baby did or did not have the suspected condition. Amniocentesis can lead to complications that result in the loss of the baby about 0.2-1% of the time.

By the end of my residency, first trimester screening in the form of blood tests done between 10-13 weeks gestation, coupled with an ultrasound measurement of the thickness of the skin at the back of the neck (nuchal translucency) was starting to gain traction. This was thought to give an earlier diagnosis of genetic abnormalities, although once again, it could only provide a probability and not a definitive diagnosis. The next recommendation for an abnormal first trimester screen would therefore be chorionic villous sampling, where a biopsy of the small portion of the early placenta was obtained in the late first trimester. The pregnancy loss rate from chorionic villous sampling was even higher than amniocentesis at ~2.1%.

The new kid on the block for prenatal screening is cell free DNA testing, which can be done as early as nine weeks gestation. With cell free DNA, a sample of the mother’s blood is drawn to assess for circulating fetal cells from the baby in the current pregnancy. This works because cells from the baby appear in the mother’s bloodstream very early in pregnancy, but cells from babies of prior pregnancies essentially clear from the mother’s bloodstream within a few days of delivery. Because the cells contain the baby’s DNA, this result is more exact than a probability but can still give false positive results for a variety of reasons.

Regardless of the method of prenatal screening, the question remains — What exactly is the goal of having an early diagnosis of a child with a genetic abnormality? Unfortunately, the answer in the medical field is so that abortion can be recommended to the mother at an earlier gestational age. Prenatal genetic testing is heavily linked to abortion, with more than 90% of babies diagnosed prenatally with Downs’ syndrome being aborted. In fact, patients may experience extreme pressure from their physicians to abort the baby if they hesitate in any way after the initial recommendation.

Does this mean there is no other role for prenatal screening or that prenatal screening is inherently evil? Not necessarily. Parents may wish to have advance warning of a child who may need special care after birth so that they can investigate resources prior to delivery that will give their baby the best quality of life possible. If the baby receives a diagnosis that is completely incompatible with life, it can allow time to bond with the baby during the limited amount of time they have and identify resources to help them with the grieving process when the baby naturally passes away. Finding these resources can be difficult, but a solid Catholic therapist/grief counselor can be invaluable. Certainly, reaching out to friends, family and faith community for prayers and support can help tremendously. In some locations, there may even be perinatal hospice services that are designed to walk alongside families pregnant with a child with a universally fatal diagnosis and provide them support along the way.

So, there can still be a good role for prenatal screening for the faithful Pro-life family who wants to honor the child that God has given them. They need to go into the screening with eyes wide open, however, because of the pressure that will be put on them by their prenatal care provider in the setting of an abnormal test. They need to be able to remain strong and protective of their child even with the medical community around them pressuring them otherwise. They also should know themselves well enough to determine if having this knowledge will be a blessing to them and their ability to prepare for what is to come, or if it will instead cause extreme anxiety. If the latter is the case, it may simply be better to decline screening. You are not a bad parent if you decide that prenatal screening is not the best choice for your family.

Regardless of the choice that you make regarding prenatal testing, in all things remain faithful to the Lord and He will bless you. I have never seen a family regret that they did not abort their child with a fatal diagnosis. Instead, they were all grateful for the brief time they had with them.