How important is the triple test?

Q: My wife is 32 years old and is into her 15th week of pregnancy. As of now she is doing quite well and her first trimester ultrasound report at 8 weeks showed a fetus of 1.56 cm CRL, heart rate 171 bpm, cervical length 4.1 cm and internal os closed. As of now she is quite comfortable and our doctor says things are progressing normally. However, now our doctor has asked us to go for a triple marker test for mental retardation. How important is this test? I understand that this test is usually done for women above 35 years of age. This will be our first child and we are very much worried.

A:Triple test is a screening test done between 16 and 18 weeks of pregnancy generally to help identify fetuses at risk of having Trisomy 21 (Down's syndrome), Trisomy 18, and neural tube defects. It does not identify all cases of mental retardation, but these 2 trisomies are the commonest. Triple test should be ideally done in all pregnant women (state, i.e. the government, cannot afford to do this on free basis) and not just those who are above 35 years of age. The reason for screening is that majority of Down’s babies are born to low risk women (including those below 35 years of age). Most women deliver babies before 35 years of age, hence more than 80% of Down’s babies are born to women less than 35 years of age.