QuestionThank you the prompt reply. My Amnio is scheduled for Tuesday, and I think I am going to go through with it, your miscarriage numbers are a lot lower than what was quoted by my doctor and in most publications (they mention 1 in 200). Where are those statistics published? Is this a new statistic?
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Followup To
Question -
I am 37 and 17 weeks pregnant, my due date is Feb 12, 2006. I had a negative screening
result in my Nuchal Translucency and blood test combination, the adjusted risk after the test for downs is 1 in 1561 but the risk for trisomy 18 has come back as 1 in 405.
I am worried about having a baby with a birth defect but I am even more worried about having an amnio due to the high rate of miscarriage (1 in 200).
This is my 2nd pregnancy and my first child is perfectly normal - he is 20 months old. I don't want to risk a miscarriage and since the risk of the amnio is higher than the results that the test brought back, my husband tells me to consider that as a factor for not having the amnio. Will my 20 week ultrasound tell me more to reassure me? I hope so. I have read that after 35, women should consider
having an amnio since the risk is of birth defects is higher than the risk of miscarriage, but after the screening test, my risk is lower. Should I count on these numbers?
Mary
Answer -
The risk of Down's syndrome at the age of 37 is 1 in 250 pregnancies. (The risk at 35 years of age is 1 in 350, and the risk at 30 years of age is 1 in 2700). You see that as you get closer to 40, the risk gets greater. At 40 the risk is 1 in 100. The risk of miscarriage from amniocentesis is 1 in 450. Therefore, when the risk of getting the disease is greater than the risk of miscarriage, we recommend the amniocentesis. At your age, the risk of the disease is greater than the risk of miscarriage from the procedure and you should have it done. On the other hand, since your nucahl translucency was good and the adjusted risk isdowns is low, you hae a good chance. Tris0my 18 is quite rare and your values are based on age risk. You risk appears to be low.
AnswerWe have always seen that the risk of miscarriage following an amniocentesis is 1 in 450. That is why, when the risk is greater than 450, we recommend amnio. At 35 years of age, since the risk for Down's is 1 in 350 (based on age alone) we recommend amniocentesis. I can't put my fingers on the exact reference, however there has not been much fluctuation in years.
