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Journalism of Courage
A first-trimester screening test can reliably identify foetuses likely to be born with Down Syndrome, providing crucial information much earlier than current testing allows. The study released a few days ago of more than 38,000 US women found that the method, which combines a blood test with ultrasound exam, can pinpoint many foetuses with the common genetic disorder 11 weeks after conception. That allows women to decide sooner whether to undergo the riskier confirmation test.
‘‘It’s going to have a big impact…throughout the world,’’ said Fergal Malone of the Royal College of Surgeons in Dublin, who led the study published in the November 10 issue of New England Journal of Medicine.
Screening before the second trimester allows those who might opt to terminate a pregnancy to make that decision when an abortion is safer and less traumatic. It also gives those who want to continue the pregnancy more time to prepare emotionally for their child’s condition, and provides earlier reassurance to those whose babies are healthy, avoiding weeks of anxiety, Malone and others said.
It is the most common major chromosomal abnormality, occurring in about 5,000 babies each year in US. It results when a baby has three, rather than two, copies of the 21st chromosome, causing developmental problems and an increased risk of health problems usually shortening life span.
Currently, women, especially those at high risk because of family history or age, are offered a blood test known as quadruple test about 16 weeks into pregnancy. Those who test positive can undergo amniocentesis to confirm the diagnosis. The newer regimen uses an ultrasound test called nuchal translucency to measure skin thickness on the back of a foetus’s neck and a blood test to measure levels of a protein called pregnancy-associated plasma protein A (PAPP-A) and a hormone, human chorionic gonadotropin (HCG).
The study involved 38,167 women at 15 US centers who underwent both procedures and then were followed to see which foetuses had Down Syndrome. The first-trimester approach identified 87 per cent of Down babies when used at 11 weeks, whereas the later quadruple test identified 81 per cent. The two tests together picked up 95 per cent of cases. Both produced false positives in about 5 per cent of cases.
Women who would opt to terminate a pregnancy based on the results can do so much earlier, when abortion is less risky and less traumatic, Malone said, adding, ‘‘By the time they are 20 weeks’ pregnant, most women feel foetal movement. We wouldn’t want to underestimate the psychological or emotional difficulty of undergoing termination that late.’’
Malone thought the approach would not result in more abortions overall. ‘‘Most women are probably going to make the same decision as before. If she decides to terminate pregnancy, this just makes it safer…,’’he said.
But Gene Rudd of the Christian Medical & Dental Associations said he was concerned that women are not always fully advised about risks of prenatal testing, and that screening could be used to eliminate babies with Down Syndrome. ‘‘What’s the goal… to rid society of Down babies? If it is, I really have to question the civility of that,’’ Rudd said. ‘‘The overwhelming number of people with Down will tell you their life is good.’’ Added Randall K. O’Bannon of the National Right to Life Committee: ‘‘These tests appear to be used only to select babies for abortion, including the 5 per cent who may not even have Down’s syndrome.
The Washington Post
