The most common chromosomal abnormality can now be detected one month before the normal testing period, claim the authors of a study published in the New England Journal of Medicine.

For well over a decade, the official standard of care has been to perform the blood tests to screen for a possible chromosomal problem at about 15 or 16 weeks into the pregnancy. But in the past several years, Boston's major hospitals and other centers with advanced obstetric care have been offering earlier screens, combined with an early ultrasound scan that can also catch signs of trouble.

This way, in order to find out in time if the fetus is affected by the Down Syndrome, the future mothers will be able to take a test 11 months after the last menstrual period. When the results suggest a high risk of chromosome problems, the woman may choose to have an invasive test such as an amniocentesis, which carries a slight risk of miscarriage, to find out for sure.

Should the tests prove that the fetus is affected, women can choose to end the pregnancy with an abortion, being a well known fact that earlier abortions are far safer, or they can make preparations for a child who will require constant attention.

The Down Syndrome is a syndrome that causes slowed growth, abnormal facial features, and mental retardation. It is caused by the extra chromosome 21. Incidence of Down syndrome is estimated at 1 per 660 births.