New screening test can predict Down syndrome in first trimester

Nov 13 2005

According to new research, an early blood test has proven to be an accurate predictor for Down syndrome.

Researchers from Columbia University Medical Center working at NewYork-Presbyterian Hospital, checked more than 38,000 pregnant women at 15 U.S. centers using a non-invasive screening test for Down syndrome.

The blood test was done in the first trimester of pregnancy, at 11 weeks and appears to have a significant advantage over the current standard screening, a blood test performed in the second trimester of pregnancy.

Mary E. D'Alton, M.D., principal investigator of the study, says the results will undoubtedly change national practice and all pregnant women should have the option of early screening for Down syndrome in their first trimester.

D'Alton who is the head of the Department of Obstetrics and Gynecology at Columbia University College of Physicians and Surgeons, and Chief of Obstetrics and Gynecology at NewYork-Presbyterian Hospital, says that screening for Down syndrome which is based on either maternal age alone, or an ultrasound or sonogram alone, are no longer justifiable.

The study which is known as the FASTER trial (First and Second Trimester Evaluation of Risk), was funded by a $13 million grant from the National Institutes of Health and the National Institute of Child Health and Human Development and is one of the largest ever grants for an obstetrical study.

The new blood test analyzes the level of a protein and hormone in the mother's blood, combined with an ultrasound or sonogram picture of the thickness of skin on the back of the baby's neck, and the results are available within five days.

This combined approach determines the odds that the baby might have Down syndrome, allowing pregnant women the option of prenatal diagnosis for Down syndrome and other chromosomal abnormalities within the first trimester of pregnancy.

The researchers found a higher detection rate in the first trimester compared to the best second trimester screening method, this is a significant advantage over the current standard screening test.

The new test was performed on 38,167 patients and 117 were found to have a fetus with Down syndrome.

These woman were then given the option to have the finding confirmed with a diagnostic exam: chorionic villus sampling (CVS) or amniocentesis.

Both these tests carry risks of complication leading to miscarriage.

Down syndrome, one of the leading causes of mental retardation and birth defects, occurs in one in 660 pregnancies.

The condition has distinct physical features and certain birth defects and medical problems.

Any woman can have a baby with Down syndrome, regardless of her age, race, health, economic status or family history, and for this reason, most pregnant women undergo testing to determine their potential to have a baby with this syndrome.

Dr. D'Alton and the research team however believe that the new screening method should only be administered by qualified, trained physicians,and she and other experts have recently formed the Maternal Fetal Medicine Foundation to facilitate physician training and quality review for the screening.

So far 1,600 physicians and sonographers nationwide have undergone training, and more are scheduled.

Information about the training and quality review program can be found at http://www.MFMF.org.

Women seeking this early screening should seek healthcare professionals with appropriate ultrasound training and who participate in ongoing quality monitoring programs.

Programs should provide sufficient information and resources for counseling regarding the different screening options and limitations of these tests.

The services should also provide access to an appropriate diagnostic test when the screening test is positive.

The study is published in the current edition of the New England Journal of Medicine.