You didn't do anything wrong. You have what's called an "incompatent cervix" and it's just something that sometimes happens. Usually it doesn't become a problem until you are well into the second trimester because that's usually when the uterus becomes heavier and to enlarged for the cervix to handle in a women with an incompatent cervix.
Usually they will put a stich in the cervix that stays there to keep the cervix from dilatng and it's usually removed around the 37 week of pregnancy or later when it's safe to go into labor.
Also you will most likely have to have a cerclage (stiching of the cervix) in future pregnancies but since your HCP is aware that this is an issue for you now they will probably do it by 12 weeks in future pregnancies.
at 6:52 AM on Nov. 25, 2010