The first trimester screen looks at a couple of enzymes in the mum's blood and a measurement of the skin behind the baby's neck. One of the Mods (Flowerchild) wrote a good description earlier in this thread.
The results give a risk figure (e.g. 1 in 450) for trisomy 21 and a risk figure for trisomy 13/18.
I don't think that a y-chromosome deletion would show up on these tests. The Y-chromosome is quite small, and a deletion that has minimal effects is probably pretty small. The first trimester screen is picking up when there is a complete extra chromosome.
If you wanted to more information, you could ask to speak to a genetic counsellor. Most women's hospitals have a genetics unit and you should be able to get an appointment by ringing up.
Reply With Quote
Bookmarks