Yesterday I received a call from the perinatologist’s office with the results of our screening. Before I explain the final results, I should preface with a little bit more information about how they calculate it. Prior to the ultrasound, we spoke with a genetic counselor who reviewed the history of our last pregnancy and discussed our general risk of a chromosomal abnormality occurring again. There are baseline risk numbers for all women, which increase with maternal age. An average 26 year old woman generally has a 0.22% risk of having a child with a chromosomal abnormality. As a ratio, this is 1/455 (meaning out of 455 women, only 1 would have a child with a chromosomal abnormality). We were told that if a woman is under 30 and has a child with a chromosomal abnormality, her baseline risk is 8 times higher. Hence, for me this means my baseline risk would be 1.6% (this is before any testing). That is still very low and means I’d have a 98.4% chance of having a child with normal chromosomes. However, when you state it as a ratio, it’s roughly 1/60. That’s a little scarier to me.
The nurse told me that after the receiving the results of my blood draw, our result is negative, or low risk. I asked her if she could give me the exact ratios that were calculated. After factoring in my baseline risk, the ultrasound and blood results, my risks are as follows: 1/10,000 for Down’s Syndrome and 1/2,700 for Trisomy 13 & 18. We are very pleased with these, as they are significantly lower than my original risk without testing. Like I said before, this screening does not give a definite confirmation either way; it merely estimates the risk. But because over 90% of these conditions are typically detected, we’re feeling optimistic about our results.
So that’s where we are right now. Of course I will keep everyone updated as we go along, and I want to say thank you for the kind emails and messages that have been sent our way.