Babies who are born prematurely are at very high risk of dying early or, if they survive, of having disabilities. So, for decades, doctors have used a particular procedure in women at risk of early delivery—encircling the cervix with a suture and pulling it tight. But it's not clear whether the procedure actually helps, and a new British study suggests there may be no point to it at all.

What they wanted to know: Does pulling the cervix tighter prevent premature delivery often enough to justify doing the procedure routinely?

What they did: The researchers are all based in London and Liverpool, but the women were seen at hospitals in the United Kingdom, Brazil, South Africa, Slovenia, Greece, and Chile. More than 45,000 women were screened, and women with a cervix 15 millimeters or shorter at 22 to 24 weeks were invited to join the study, because women with short cervices are much more likely to deliver prematurely. The 253 women who agreed were randomly assigned to have either cervical cerclage, as the procedure is called, or expectant management—close monitoring instead of immediate treatment. (Obviously, there was no way to hide from the women or doctors which group they'd been assigned to, as would happen in a placebo-controlled double-blind drug trial.)

What they found: Women who had the cervical cerclage were only slightly less likely to deliver prematurely, and their babies were no less likely to die or have health problems. The researchers concluded that this widely used procedure did not help enough to justify performing it routinely on women with short cervices.

What it means to you: Cervical cerclage may not be that helpful, but the researchers say that since premature delivery is so risky, even a slightly lower chance of premature delivery could make the procedure worthwhile.

Caveats: The study excluded women with major fetal abnormalities or regular, painful contractions, women whose cervices were dilated at the time of screening, and women who'd had cervical cerclage before, so the results may not apply to those women.

Find out more: The American College of Obstetricians and Gynecologists' press release on an earlier meta-analysis of studies on cervical cerclage for preventing early deliveries: http://www.acog.org/from_home/publications/press_releases/nr08-29-03-2.cfm

Read the article: To, M.S., Alfirevic, Z., Heath, V.C.F., Cicero, S., Cacho, A.M., Williamson, P.R., and K.H. Nicolaides, on behalf of the Fetal Medicine Foundation Second Trimester Screening Group. "Cervical Cerclage for Prevention of Preterm Delivery in Women With Short Cervix." The Lancet. June 5, 2004, Vol. 363, pp. 1849-1853.