Hi Aru ,
Welcome to HCM.
Unless there are strong risk factors involved, you do not have to undergo amniocentesis
Your age is a risk factor but just for that you need not do the test.
Some obstetricians follow a certain procedure, and this may be part of their routine test in pregnant ladies over 34 yrs. of age.
Since this is your second pregnancy
you cannot be called elderly primi. In elderly Primi, such tests are warranted.