The opening of the cervix(cervical os) that dilates during birth closes over 2 to 6 weeks. If this is a first birth, then the cervical size and shape does not ever quite return to the never pregnant configuration. In brief: Return to normal? The opening of the cervix(cervical os) that dilates during birth closes over 2 to 6 weeks. If this is a first birth, then the cervical size and shape does not ever quite return to the never pregnant configuration. Would you like to video or text chat with me?