What Does Thick Neck Skin In Fetus Indicate?

Hi I m 12 weeks pregnant n had bleeding so was hospitalised for two days n hv suggested complete bed rest. I also had a ultrasound dn to track the feotus cardiac activity, it s normal.but the doc say tAt my baby has a thick neck skin 4.5mm so can hv genetic disorder hav dn a blood test too to detect the same but reports wil cm after 3 days , I m worried wil my child hv some prob wil he b havin Down syndrome plz advice. I m takin pause500,sustain,dupastan, n folvite