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We have often discussed the issues of pregnancy planning and conception. This is an extremely important stage in the life of a woman and a couple. Additionally, the period of pregnancy itself is also significant. A short cervix affects the course of pregnancy and requires increased attention from the obstetrician-gynecologist.
The cervix is an anatomical part of the uterus that should remain tightly closed throughout pregnancy and hold the fetus in the uterine cavity. During labor, the cervix first shortens and then dilates. Therefore, it is extremely important that the cervix does not shorten and remains tightly closed until the full-term pregnancy (37 weeks).
In a study involving 930 pregnant women, the average cervical length at 8 weeks of pregnancy was nearly 41 mm. (Reference range of the weekly uterine cervical length at 8 to 38 weeks of gestation Esmat Jafari-Dehkordi, Atoosa Adibi, Mehri Sirus; Medically reviewed by Valinda Riggins Nwadike, MD, MPH, OB/GYN — Written by Jessica Jondle on October 2, 2019)
As the pregnancy progresses, the cervix begins to shorten in preparation for labor. This shortening, dilation, effacement, and softening of the cervix are the changes that allow the baby to pass through the birth canal.
If a woman has a short cervix even before pregnancy or in early pregnancy, the physiological shortening that occurs during pregnancy may make it too short too early, which can lead to preterm birth.
A study found that women with a cervical length of 15 mm or less at 23 weeks of pregnancy accounted for the majority of spontaneous preterm births occurring at 32 weeks or earlier. (Cervical length at 23 weeks of gestation: prediction of spontaneous preterm delivery, V. C. F. Heath, T. R. Southall, A. P. Souka, A. Elisseou, Professor K. H. Nicolaides; Medically reviewed by Valinda Riggins Nwadike, MD, MPH, OB/GYN — Written by Jessica Jondle on October 2, 2019)
Premature cervical shortening before labor, especially before 24 weeks, is associated with a higher risk of spontaneous preterm birth. Detecting a short cervix is very important, as timely intervention can prolong the pregnancy compared to a watchful waiting approach.
Causes of a short cervix:
- Anatomically short cervix
- Previous procedures on the cervix (conization for dysplasia, radiofrequency or diathermocoagulation)
- Hormonal imbalances (progesterone deficiency during pregnancy)
- Inflammatory processes that irritate the cervix and may cause premature shortening
- Complicated birth history
- Multiple pregnancy
- History of preterm birth
How to assess and detect cervical shortening?
Since cervical shortening begins at the internal os, it can initially be detected during ultrasound before it becomes evident during a physical exam.
The international standard for assessing cervical length is cervicometry. From 16 to 24 weeks of pregnancy, it is recommended to perform cervicometry every 2 weeks.
Normal cervical length during pregnancy
Short cervix during pregnancy
Can cervical length be measured using a transabdominal probe?
This imaging method is not suitable for objectively assessing cervical length. A full bladder may create a false impression of cervical length. When the bladder is full, the cervix may appear longer than it actually is, which can influence pregnancy management decisions.
Symptoms and signs of cervical shortening
Unfortunately, there are no symptoms in a pregnant woman’s well-being that clearly indicate cervical shortening. The only way to detect it in time is by performing an ultrasound. If any symptoms appear (such as bloody discharge, lower abdominal pain, back pain, or changes in vaginal discharge), you should urgently consult your obstetrician-gynecologist.
Is it possible to carry a pregnancy with a short cervix?
Definitely yes. But it should be noted that managing such a pregnancy requires special attention and more frequent ultrasound monitoring.
During pregnancy, cervicometry is important — it is an ultrasound where the cervical length is measured using a transvaginal probe.
Also, when planning a pregnancy with a short cervix, it’s important to understand that physical activity, sexual intercourse, and sports are contraindicated.
What methods are available to support the cervix during pregnancy?
- First of all, careful ultrasound monitoring is necessary. The critical period is 18–25 weeks of pregnancy, as this is when the fetus gains weight rapidly, increasing pressure on the cervix.
- There are specific medications (usually progesterone-based) used vaginally to strengthen the cervix.
- Placement of an obstetric pessary — a silicone ring that supports and relieves the cervix, preventing it from shortening.
Cervical pessary in pregnant women with a short cervix (PECEP): an open-label randomised controlled trial
Maria Goya, MDa,b ∙ Laia Pratcorona, MDa ∙ Carme Merced, MDa ∙ Carlota Rodó, MDa ∙ Leonor Valle, PhDd ∙ Azahar Romero, MDd ∙ et al.
Obstet Gynecol Sci Obstet Gynecol Sci OGS Obstetrics & Gynecology Science 2287-8572 2287-8580 Korean Society of Obstetrics and Gynecology; Korean Society of Contraception and Reproductive Health; Korean Society of Gynecologic Endocrinology; Korean Society of Gynecologic Endoscopy and Minimal Invasive Surgery; Korean Society of Maternal Fetal Medicine; Korean Society of Ultrasound in Obstetrics and Gynecology
- Cervical cerclage — a surgical stitch on the cervix
Conclusions
Thus, cervical length is a good and fairly objective predictor of preterm birth. Beyond conception and carrying the pregnancy, it is extremely important for the pregnancy to reach full term and for delivery to occur at a safe time. That’s why identifying and monitoring a short cervix is key to preventing cervical insufficiency — early shortening and dilation of the cervix.
It is absolutely possible to carry a pregnancy with a short cervix, but it does require close monitoring and attentive management by an obstetrician-gynecologist. The most important thing is to stay under the supervision of your doctor and follow all recommendations — then your pregnancy will be safe and full-term delivery will be achieved.