Nuchal measurement

Anybody knows how accurate is it? Im going soon to check it out and my obgyn said it would be good no matter the results to get nipt test beacuse i had 3 miscarriages before this pregnancy at 6,7 weeks and now im almost 11 weeks on asprin and progesterone .. Nipt testing is quite expensive in my country and i would kinda have a little problem affording it..

Is it necessary or is it enough to have good results of nuchal measurement to be sure my baby doesnt have down syndrome and is developing corectly?