Premature Birth: Managing Risk Factors
Normal cervical length mid-pregnancy is 30 to 40 millimeters. Women with a cervical length below 30 millimeters may require closer observation or testing because of their risk of spontaneous preterm delivery, although many women with a short cervix still deliver at term. Your health care professional can identify a shortened cervix by taking measurements during the second and third trimesters of pregnancy. The exact stage at which doctors conduct cervical measurements may vary, but they typically begin at some point in the second trimester, around 20 to 24 weeks of gestation. Ask your health care professional about measuring your cervix at least twice during your second trimester, because your cervix may become shortened as the pregnancy advances.
For many years, transvaginal ultrasound (TVU) was the standard method for cervical measurement. This involves inserting an ultrasound wand into the vaginal canal to reach the cervix, making it possible to measure its length. TVU requires a trained ultrasound technician and specialized equipment.
An obstetrician has designed a device that can be used by a physician or midwife to measure the cervix during an office visit. A speculum is inserted, followed by the device, which is then used to measure the vaginal cervix length. Studies have shown that this device, called CerviLenz, is accurate and may provide an easier and less expensive way of measuring the cervix.
If your health care professional finds that you have a shortened cervix, you will be observed more closely throughout your pregnancy, and there are several treatment options that may be recommended. Recent research has shown a decrease in premature births with the use of progesterone therapy in some women. Progesterone can be administered in a number of ways, including as a vaginal gel, capsule or suppository, or intramuscularly as a shot. One recent study of a vaginal progesterone gel found that treatment started before 24 weeks for women with a short cervix was associated with a 45 percent reduction in the rate of preterm birth before 33 weeks and with improved outcomes for the babies.
Cervical cerclage is another treatment that has shown significant reductions in preterm births and infant mortality. Cerclage is a surgical procedure that involves placing a stitch through the cervix, essentially sewing it shut to prevent it from opening too early.
If a woman is in preterm labor, steroids may be given to help mature the baby's lungs and reduce the risk of respiratory distress syndrome in premature babies.
