What is Down Syndrome?
Down Syndrome is a genetic condition where an affected individual has an extra chromosome 21 (Trisomy 21). It is the most common cause of genetically abnormal births in humans. It is not the only condition to commonly affect human pregnancies. Patau and Edward Syndromes (Trisomy 13 and 18) also are common among the genetically affected pregnancies. In general Down's Syndrome occurs in 1 in 800 pregnancies. Most of affected pregnancies are miscarried as the body screens off the abnormal. But some do get past the test and grow on to be born as babies. Edward and Patau babies will not be able to live past the hours or days as they have severe brain heart and other abnormalities. These 2 conditions are generally considered life limiting conditions. Down Syndrome babies live on with over 95% being dependent on their parents forever.

These conditions are related with maternal age. At 25 the chance is 1 in 1500. This rises to 1 in 300 at 35, 1in 250 at 37 and 1% at 39. Every mother to be has a risk of this condition.

How do I Check for Down Syndrome?
With the introduction of ultrasound scans, especially with higher resolution machines, 30-50% of Down Syndrome babies can be diagnosed during pregnancy. 30% of babies with Down syndrome appear normal on ultrasound. This is the reason why many tests have been developed to increase the detection rate.

The First Trimester Screen (FTS) has revolutionized the screening of Down, Edward and Patau syndromes. This is a combined test. It calculates the individual risk of the baby using scan parameters and blood levels of certain hormones of pregnancy. It is called the combined test because of this. It is not merely a mathematical estimate. The detection rate is 85%. Combined with other features in the baby (expert scans) the accuracy can be up to 90%. This test has reduced the need for amniocentesis by ten-fold and doubling the detection rate.  FTS is performed from the 11th up to the 14th week of pregnancy.

The detailed scan is a structural survey of the baby. Only 50% of babies with down syndrome have structural defects and are detected by ultrasound at the 2nd trimester detailed scan.

The test with highest detection rate for down syndrome detects fetal DNA directly from a sample of mother's blood. It has many names - NICC, NIPT and NIPS. Various labs offer the test with various names but they utilize different techniques. But all detect Baby's DNA in mother's circulation detectable from the 8th weeks of pregnancy. Some are marginally better than others. They detect from 95% up to 99% of affected babies. These tests also can detect down to the 10 most common conditions affecting babies. They can be done from the 9th week of pregnancy and onwards with a simple blood test from the mom.

Who Should Have The Test?
Everyone should be offered screening for Down Syndrome in pregnancy. It is then up to the individual to opt for testing or not.
As Down Syndrome is thought to only affect 'older' women, most younger women do not have any tests offered for the condition. This fact is not true. All pregnancies of women of all ages can be affected by this group of condition. The chances are higher in older women but all women have a chance. Because only 'older' women have tests done, TODAY, most Down Syndrome babies are born to younger lower risk moms.

Why should I test?
This is a very personal question. And it invokes personal answers.

There was a time when testing was strongly associated with termination of pregnancy. 

Pregnancy with a Down syndrome fetus can have complications: structural fetal anomalies and growth abnormalities. Some structural anomalies are also associated with other syndromes. Down syndrome fetuses are smaller and may show growth abnormalities prior to birth. These may cause the obstetricians to take wrong decisions and give wrong information should the diagnosis not be confirmed.

Planning your life with a Downs child is important. Immediate surgery may be needed for problems in the brain, heart and bowels. Special parenting skills and schools is most probably needed. All this planning can begin from before the birth of the child.

​Medical care has improved. The care of Down Syndrome patients has improved. There is significant group of women who test to know early and begin research and planning. Some babies have structural problem that necessitate delivery in specialized units.

Ultimately to test or not remain the wish of the couples. Today more couples test to know and to prepare rather than to terminate the pregnancy. The stigma of testing is rapidly vanishing as our society becomes more informed and strife to be more informed.