Women often search for a cervical length chart in mm that includes the normal cervical length at 7 weeks, normal cervical length at 30 weeks etc but actually the only measurement to go by is the normal cervical length. What is a short cervical length? A cervix that is less than 25 mm is considered a short cervix. In obstetric and gynecological imaging, the cervical length is defined as the distance between the internal cervical os and the external cervical os. Radiographic assessment Ultrasound the cervical length is most accurately assessed on a transv... The normal cervical length in pregnancy typically ranges between 3 to 5 cm, which is considered ideal for a full-term birth. A shorter cervix may increase the risk of preterm labor, making it important to refer to a reliable cervix length chart during pregnancy for proper assessment. Learn why cervical length matters during pregnancy and how it is measured by trimester. Find out the normal and abnormal ranges, the risks of a short cervix, and the treatment options for high-risk pregnancies.