Mine was measured via U/S, I think they can tell checking internally too, because my doctor checked me once and said it's still long because I thought I was going into preterm labor. But measuring and dilating aren't the same thing, as you get closer to your due date your cervix will shorten, dilating is the opening of your cervix. Bacteria infections are common during pregnancy and easily treated with antibiotics. Usually they'll measure your cervix at about your halfway point in your U/S.