Cervical length in pregnancy: when it’s normal and when it’s not

How big is the cervix during pregnancy? What is meant by cervical shortening? What are the risks and treatments for a shortened cervix in pregnancy? Here are all the answers!

The neck of the uterus , also called the cervix, is the end of the uterus that protrudes into the vagina.

Normally, before pregnancy , it is closed, rigid and at least 3 centimeters long .

As the body prepares for labor , however, the cervix shortens , becomes thinner and softer, and dilates up to 10 centimeters, so the baby can pass through the birth canal to be born.

If the cervix starts to open before 37 weeks, you run the risk of a  premature birth (also called preterm birth ) which could put your baby’s health at risk. In fact, the earlier the birth is, the more unprepared the fetus is to face life outside the womb.

For this reason, if you experience labor symptoms before 37 weeks (such as regular or frequent contractions or a dull ache in your lower back) it’s important to go to the emergency room right away to be evaluated.

During the visit, the doctor will evaluate whether the cervix has begun to open and may perform an ultrasound to measure the cervical length ( cervicometry ) or the  length of the cervix . This parameter, in fact, is an excellent indicator to understand how imminent the birth is up to about 34-35 weeks. Subsequently, the clinical evaluation remains more reliable.


Kathryn Barlow is an OB/GYN doctor, which is the medical specialty that deals with the care of women's reproductive health, including pregnancy and childbirth.

Obstetricians provide care to women during pregnancy, labor, and delivery, while gynecologists focus on the health of the female reproductive system, including the ovaries, uterus, vagina, and breasts. OB/GYN doctors are trained to provide medical and surgical care for a wide range of conditions related to women's reproductive health.

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