Girls, at 19 weeks and 3 days, the cervix length was 33mm, is that nor…

Girls, at 19 weeks and 3 days, the cervix length was 33mm, is that normal? Although the clinic wrote 41mm, and in private clinic 33mm? Just one story I know, a girl came for ultrasound at 27 weeks and her cervix had already opened up by 16mm That's why I'm worried now.