August 19, 2011 — A growing body of evidence suggests that measuring women's cervical length during pregnancy could identify women who are likely to deliver prematurely and thus should receive treatment with the hormone progesterone, the Philadelphia Inquirer reports.
According to a recent study in the journal Ultrasound in Obstetrics & Gynecology, pregnant women with shortened cervixes who used a daily progesterone gel were 50% less likely to deliver before 28 weeks than women with the condition who did not use the gel. Further, the study found fewer preterm births at nearly all gestational ages, fewer newborns weighing less than 3.3 pounds and fewer cases of respiratory distress in infants born to women treated with progesterone.
Researchers involved in the study are calling on obstetrical groups to update their pregnancy guidelines to include cervical-length screening, which involves a five-minute vaginal ultrasound about halfway through pregnancy. The cervix is about 1.5 inches long in most women, according to the Inquirer. Research by Vincenzo Berghella, director of maternal-fetal medicine at Thomas Jefferson University, and colleagues found that a cervical length of 0.4 inches to 0.8 inches at 19 weeks to 24 weeks of pregnancy was optimal for progesterone therapy. The treatment was not effective in women with cervixes of shorter lengths.
Although cervical shortening is relatively rare -- studies show it affects about 2% of pregnancies -- doctors are eager to identify controllable factors that contribute to preterm birth. The preterm birth rate has been rising for 30 years, and many known risk factors -- including obesity, advanced age, carrying multiples and infertility treatment -- are difficult or impossible to treat.
Cervical-length screening also would be cost-effective. An analysis by Yale University researchers found that if physicians adopted screening and progesterone therapy, 10,000 fewer infants would be born before 34 weeks in the U.S. each year. The potential savings would be $19 million in hospital-care costs per 100,000 women screened, or about $760 million annually.
Berghella contributed to draft guidelines that would make cervical-length screening and progesterone therapy a standard part of obstetric care. The American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine are working on a final version, he said (McCullough, Philadelphia Inquirer, 8/18).