Girls, hi ? I had my second ultrasound yesterday. The doctor said tha…

Girls, hi ? I had my second ultrasound yesterday. The doctor said that "the cervix is good - 30 mm". This is a very good doctor with a name in gynecology. But, from the posts here I understood that 3 cm at 21 weeks is little?? Or is this only in post-Soviet space such standards? ? In short, who had a cervix of 30 at my due date, what did you say/were prescribed. I'm going to my doctor on December 13th, so I'm curious if I should be afraid and run to her already? ??‍♀️