Is Down Syndrome on the Decline Due to Prenatal Testing?

A new prenatal blood test can tell pregnant women as early as ten weeks into pregnancy if their fetus may have Down Syndrome. 

The number of Down Syndrome babies has been shrinking over the past two decades, for various reasons.  At the same time, more services exist for children with Down Syndrome to grow up and lead relatively independent lives. 

What percentage of parents decide to abort their fetus if they learn that it has certain disorders through prenatal testing?  If abortion is not the reason for the decline in Down Syndrome babies, is it possible that those who have someone with Down Syndrome in their family decide not to have children?  The odds of having a baby with Down Syndrome increases as a woman gets older.  Pregnant women 35 years old and up are given prenatal exams not only to determine whether or not the fetus has Down Syndrome, but also to see whether or not the fetus is alive, as older women are more likely to have miscarriages. 

In some countries, pregnant women who go for prenatal exams are not told the sex of the fetus, for fear that they will abort one that is female.  It would be irresponsible for doctors not to tell potential mothers that their baby-to-be has a disorder that will require special care, as arrangements for services take time.  If a pregnant woman has no support network to help look after an infant with special needs, will she be more likely to abort the fetus?  As the number of single mothers increases, this may be something to investigate.