I had the same issue as you did. My family doctor told me that I did not need to do the amnio test unless my blood test was positive, but when I registered for the hospital, the nurse said that all women over 35 need to do the amniocentesis test. This is because 1) women over 35 are at more risk of Down syndrome or other chromosomal problems; 2) the result of the blood test is based on estimates and only amnio test can diagnose such abnormalities. I talked to my family doctor again and this time he said what the nurse said was true and the reason why he did not request me to do the amnio test was because he thought that I was 34! So double check with your doctor. It is possible he messes up your age just like what my doctor did.