12 week NT scan

I had the NT scan today where they measure the babies and check for down syndrome. I guess with twins the NT scan is only 70% accurate compared to a singleton is 90% accurate. the necks were 1.6 and 1.7. they were measuring 7.5 cm 7.6 cm in length. i took a bunch of blood tests but i have no intention of getting an amnio or cvs. we got to record a 20 min. video and they were moving a lot. One of the babies pushed against something and flew back an inch or so. It was so cute. He pulled up the 3d scan and they looked like two aliens with their funny skulls. my next u/s is in 4 weeks and they will start checking my cervix every 2 weeks.