Understanding a Positive AFP Test Result: What Does It Mean?

Question
I'm 35 years old.  I have one daughter, who just turned 1 in November.  Last menstrual date August 31, 2004.

I was just notified that my AFP test came back positive.  The nurse advised me that the "cut-off" for normal is 1 in 195 chance of Down's and mine came back 1 in 150 chance.  How concerned should I be?  Do the majority of these come back normal after further testing?

Thank you!
Susan

Answer
At the age of 35, the risk for Down's syndrome is 1 in 350 just based on your age. If the AFP showed a 1 in 150 chance it is significant and we must recommend amniocentesis to rule out the disease. Remember that you have a 149 in 150 chance of having a perfectly normal baby, so yes, the majority of these come back norml. However, that 1 in 150 is worrisome. An amniocentesis will be 100% accurate and you will then know for sure and will not worry.