Please can you explain this in genetic terms?
As I understood it, sex is determined by the presence, or absence, of a Y chromosome, at the 23rd pair.
While exceptions exist, they're incredibly rare genetic observations and I have never heard or read it referred to as a "spectrum".
Well, they can ...
Doctor's in the UK offer screening for Down's syndrome, Edwards' syndrome and Patau's syndrome at 10-14 weeks.