First Trimester Screening

Just a heads up, I’ll be blogging about this pregnancy quite a bit. For one thing, it’s all I can think about these days, what with the pregnesia and all. And for another, information about pregnancies in my age group is pretty scarce, so I want to share as much as I can.

So last week I had what they call a first trimester screening. It’s a genetic test for Down syndrome as well as Trisomy 13 or 18. There are two parts to it, first an ultrasound technician does some very specific measurements at the nape of the baby’s neck. (No, I have no idea how they can see anything on those ultrasounds, but she IS a professional.) They also look at the bridge of the baby’s nose. They’re looking for specific markers that indicate Down syndrome. Then they do a blood test (fortunately only a finger prick this time) and send that off to a lab in New York. The combination of the two give you the likelihood of a chromosomal disorder.

It’s called a screening because unlike more invasive tests like amniocentesis it only gives you probabilities. If the first trimester screening comes back with increased likelihood of a chromosomal disorder then they refer you for amniocentesis. Because of my ADVANCED MATERNAL AGE, my numbers are heavily skewed on the onset, but miracles of miracles I did very well.

For a woman of 35 the chance of Down syndrome is 1 in 350. Prior to screening my risk was 1 in 16. Now it’s only 1 in 217. I still have to meet with the genetic counselor, but it’s much better than I expected. For a woman of 35 the chance of Trisomy 13 or 18 disorders the chance is 1 in 150. Prior to screening my risk was 1 in 29. Now my risk is 1 in 561, lower than a significantly younger woman. Bottom line is that my numbers are much better than could be expected. The perinatologist is very pleased.