At the age of 31 years, the risk of occurrence of Down's syndrome (DS) is about the same as in the general population (i.e. 1 in 800). It increases in women above the age of 35 years. The risk will increase as the age will advance.
With the previous birth of child with Down's syndrome, the risk of recurrence is taken as 1 in 100 i.e. out of 100 women with the birth of Down's syndrome in the previous pregnancy, one woman may have recurrence of the Down's syndrome in subsequent pregnancy. It is advisable that such women shall consider the possibility of antenatal diagnosis of DS in the subsequent pregnancy - where
a piece of Chorion villus (a piece of placenta) is taken out at 11th week of pregnancy under ultrasound guidance for direct chromosomal studies. The accuracy of diagnosis is greater than 95 -98%. And the risk of loss of pregnancy (abortion) is less than 3%.
No other test is required either in the wife or the husband.
There is no utility of triple test during pregnancy for such women who already have the risk of recurrence of 1 in 100.
The only way to exclude the diagnosis of DS in the fetus is by direct chromosomal examination.
The facilities for this test are available at Delhi, Lucknow, Bombay and other Metros.