Uy, first thing, please talk to your OB right away about this result, ha? They need to explain what it means for your specific pregnancy, kasi bawat mama is different.
From what I understand, cervical length measurements during pregnancy are something your doctor monitors closely, especially early on, so don't stress alone, get clarity from them ASAP so you know what to do next. A few of us moms learned the hard way na hindi dapat maghintay with anything scan-related. Your OB will have the full picture of what's normal for you at 19 weeks, and they can guide you properly. Sending you good thoughts!