with my last pregnancy I was diagnosed with a short cervix at 23 weeks...at 27 weeks my cervix measured 1.5 and I was dialated to 1cm. After that I was put on procardia daily, progesterone shots and strict bed rest. I made it to 37 weeks when I had my DD.
Follow Dr's orders, take it really easy, call for any cramping or anything that worries you. I know how scary it can be but know that you can stay dialated like that for a long term. I was basically told that I would be having DD early when they saw my measurments at 27 weeks but they couldn't say how early. With all of the meds and bed rest I was very happy to make it to full term exactly.