Down Syndrome Risk

by Jean
(South Africa)

What is the risk of a Down Syndrome baby when a pregnant mother is over 40?

I have a friend, age 44, who just discovered that she is expecting her second baby. She had the first one at age 40. She is fit and in good health.

What is the risk of Down Syndrome for her baby?

Answer

According to the National Association for Down Syndrome (USA), 80% of babies born with Down Syndrome are born to women under the age of 35 years.

They report that the risk of having a Down syndrome baby is 1 in 400 if the mother is between the ages 35-40 years old in the USA.

If the mother is over 40 years of age, then the risk of Down syndrome is 1 in 110.

At age 45 the statistics are 1 in 32 births and at age 49 it is 1 in 12 births.

BUT, looking at these figures more positively, at age 45, a woman has a 97% chance of having a baby without Down syndrome and even at age 49, she has a 92% chance of a baby without Down syndrome!


An nuchal scan is an ultrasound scan that may help identify higher RISKS of Down syndrome. It is performed between 11-13 weeks and measures the amount of fluid in the nuchal fold, which is behind the neck of the developing baby.

There are also other more invasive tests that may be performed, such as amniocentesis.

Apparently all the tests have about a 5% rate of FALSE positives.

More detailed info with references will be provided when we write a full page about Down syndrome in the pregnancy section of this site.