A new combination test can give much earlier warning that a fetus is likely to be born with Down syndrome, according to a new study published today in the New England Journal of Medicine.
A study involving more than 38,000 pregnant women showed that the combination test could detect 87% of Down cases as early as 11 weeks into the pregnancy. The blood test now used in the second trimester detects about 80% of cases.
The first-trimester test combines a blood test with an ultrasound exam. It can pinpoint fetusus with the common genetic disorder just eleven weeks after conception. But word of the study brought criticism from opponents of abortion and from those who object to its use to prevent the birth of children with Down syndrome.
"We believe every pregnant woman should have it," said Dr. Michael Y. Divon, chairman of obstetrics and gynecology at Lenox Hill Hospital in New York, according to The Los Angeles Times.
Screening women before the second trimester allows those who might opt to terminate a pregnancy to make that decision when doctors say 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, said Fergal D. Malone of the Royal College of Surgeons in Dublin, who led the study.
The American College of Obstetricians and Gynecologists said it will update its guidance to physicians to reflect the findings of the study, the largest of its kind ever conducted.
Down syndrome, which occurs in one of every 660 to 800 pregnancies, is one of the leading causes of mental retardation. Children born with the syndrome have distinctive facial features eyes that slant upwards; small ears, nose and mouth; and a flattened nasal bridge and other birth defects and medical problems.
The problem is most often associated with pregnancy in older women.
The current test -- known as the quadruple test -- is given about 16 weeks into a pregnancy. Women who test positive can then undergo a procedure called amniocentesis to confirm the diagnosis.
The newer regimen uses an ultrasound test to measure the thickness of the skin on the back of a fetus's neck and a blood test to measure levels of a protein called pregnancy-associated plasma protein A (PAPP-A) and a hormone known as human chorionic gonadotropin (HCG).
