Under normal circumstances, the length of the cervical canal, which should be more than three centimeters, is within the normal range. A woman’s cervix should be greater than three centimeters to be considered normal. Usually in early pregnancy, the cervical canal does not change much and should be more than three centimeters in length. In 22 weeks to 24 weeks of pregnancy, a cervical examination is done and if the length of the cervix is less than three centimeters, this condition indicates that the cervix is relatively short and prone to symptoms such as miscarriage. Therefore, in the middle of pregnancy, the cervical length is within the normal range, which can reduce the miscarriage situation. Usually at the end of pregnancy, near the time of delivery, the cervical canal basically disappears. It is also a normal physiological phenomenon. Therefore, after pregnancy, in the middle of pregnancy, it is better to visit the obstetrician and gynecologist regularly and have a cervical examination to see if the length of the cervical canal is normal at the same time as the pregnancy test. In general, if the cervix is less than 2.5 cm in the middle of pregnancy, you need to have regular obstetric checkups and pay more attention to see if there is vaginal bleeding and so on. Usually you need to take more rest, try to avoid excessive exercise and strain, avoid doing some weight-bearing and abdominal pressure work, and avoid intercourse to avoid premature birth. In short, if the cervical canal is less than 2.5 cm in the middle of pregnancy, it is easy to deliver prematurely.