Taking care of yourself during pregnancy, has always been a trusted form of prevention for preterm births, so avoiding habits such as smoking and overeating are recommended. Sometimes, even women who stay healthy deliver preterm with no reasonable explanation. However, studies show that there could be a very obvious and physical predictor as to whether or not you will deliver your baby preterm.
Although controversial, there have been new recommendations that the cervix should be measured (transvaginally) in the midtrimester of every pregnancy in order to assess the possibility of a preterm birth. Critics of universal screening have cited a concern that facilities for transvaginal ultrasound screening are not widely enough available. There also is concern about the potential misuse or overuse of technology, and concern that many women will undergo treatment unnecessarily.
A recent review was published by one of the investigators of the study promoting the use of a hormone gel (progesterone) intravaginally to treat such shortened cervices. This investigator was also a paid consultant for the company who manufactured the progesterone gel and therefore, had a serious conflict of interest in her recommendations. Nevertheless, there is mounting evidence that a cervical length measuring between 10-20 mm places the pregnancy at increased risk for early delivery. It has long been known that women with a shorter cervix are more likely to give birth preterm. However, the best management approach eluded clinicians until several studies demonstrated that women who had a history of preterm birth fared better when they were given weekly injections of progesterone (17a-OH progesterone caproate). In patients without a history of preterm birth, the treatment was not given; that is, until recent studies demonstrated shortened cervices, identified at midterm, had better outcomes when the patient was treated with a progesterone gel intravaginally.
Preterm labor, defined as birth before 37-weeks of pregnancy. Cervical insufficiency results when the cervix dilates (without labor contractions) leading to a preterm birth. Shortened cervices are more likely to have cervical insufficiency. With that said, ACOG (American College of Obstetricians and Gynecologists), a governing body for OB/GYNs) fell short of mandating routine transvaginal cervical length screening in women without prior preterm birth.
When you become pregnant, it will be up to your physician or midwife to request a midtrimester ultrasound, which looks at the cervix as well as the fetus for anomalies. If your cervix is abnormally short, you and your physician can be prepared for preterm labor and intravaginal progesterone can be offered. Another form of management also sounds good in the form of a cervical cerclage, or a stitching of the cervix to prevent labor before the 37th week. However, this plan of management remains controversial with several studies showing no improvement in outcomes for preterm fetuses. Also, the downside of a cervical cerclage is rupture of membranes and infection, which may ultimately lead to hysterectomy. With a shortened cervix, patients may be advised to take bed rest in your last trimester to prevent any unnecessary pressure on the birth canal.
A short cervix is probably not a feature you’ve ever included in a physical description of yourself, but when you become pregnant, it could become the difference between a preterm infant and a baby that has grown to term.
- Yvonne S. Thornton, M. D., M. P. H.
Alfirevic Z, Owen J, Carreras Moratonas E, Sharp AN, Szychowski JM, Goya M. Vaginal progesterone, cerclage or cervical pessary for preventing preterm birth in asymptomatic singleton pregnant women with history of preterm birth and a sonographic short cervix. Ultrasound Obstet Gynecol. 2012 Sep 18. doi: 10.1002/uog.12300. [Epub ahead of print]
Cerclage for the prevention of preterm birth in high risk women receiving intramuscular 17-α-hydroxyprogesterone caproate.Szychowski JM, Berghella V, Owen J, Hankins G, Iams JD, Sheffield JS, Perez-Delboy A, Wing DA, Guzman ER; for the Vaginal Ultrasound Trial Consortium.J Matern Fetal Neonatal Med. 2012 Aug 24.