cervical length

Miranda
I'm currently almost 25 weeks and have been having some pain and pressure down low for approximately one month.  I informed my OB and he thought it was most likely round ligament pain and would subside with time.  Well fast forward to one week ago and it's still just as bad, if not worse, so I let him know.  He scheduled me for an ultrasound this morning to check my cervical length.  The tech informed me that it is right at 3 but they really like to see it a bit more.  Has anyone had this happen and if so what was the outcome?