Susiedotcom, I just wanted to add my story aswell and hope that it may help you a bit.
Exactly like you, this is our first and we had the nuchal scan. I asked the sonographer at the time if everything appeared Ok and she said that yes, the back of the neck measurement was only 1.9mm and there was a clearly visible nasal bone. Normally (although not guaranteed) at an early scan, the nasal bone isn't visible in a child with DS.
So we went away very happy, only to get a call two days later to say that our baby had come back as high risk for DS. We felt like our life was crumbling around us, we'd already lost one baby at 6 weeks PG and we really felt that everything was stacked against us.
Exactly the same as you, it was my low PAPP-A result that had changed our risk from 1:750 to 1:35.
We opted for the CVS, which was bearable. But then 24 hours later, they called to say that they hadn't got enough tissue and I needed to go back in and have another one. I refused due to the risk of miscarriage and I thought to have two CVS in 48 hours was a massive risk. So we opted to have an Amnio.
Well, I'm now coming up to 26 weeks PG with a perfectly healthy little girl. The risk of a low PAPP-A is that it can cause growth problems and may possibly mean a small baby, but at our 21 week scan, our little Jelly was bang on average size - right along the middle line. So, so far so good.
Please remember that the Nuchal Scan/Blood Test only gives you a "Risk" factor so please bear this in mind.
I'm praying that everything will be fine for you, as it was for us. I'm sure it will be and if you want to, you can then find out the gender. I was convinced that I was having a boy but was soooo thrilled to be having a girl. So far, virtually every item in Jelly's wardrobe is pink - poor child!!
I will come back to find out your result. In the meantime, you and DH be there for each other.
xxxx