Two screening tests often used to predict preterm delivery in first-time pregnancies have been found to have low accuracy and do not appear suitable for widespread screening, a new study suggested Tuesday.
The study, published in the Journal of the American Medical Association, showed that neither transvaginal cervical measurement nor fetal fibronectin test, used separately or together, adequately predicts which pregnant women are likely to deliver prematurely.
"These methods of assessing women in their first pregnancy do not identify most of those who will later go on to have a spontaneous preterm delivery," senior author Uma Reddy of the U.S. National Institutes of Health, said in a statement.
"There is a need to develop better screening tests that can be performed early in pregnancy."
Preterm birth, defined as a birth before 37 weeks of pregnancy, is the leading cause of neonatal death or long-term disability.
Currently, two screening tests are often used to try to predict expectant mothers who are at high risk for preterm birth, which is hard to predict until it begins.
One involved routine ultrasound examination of the uterine cervix, the lower part of the uterus that shortens and opens during labor. Previous studies have indicated that a short cervix early in pregnancy could be a warning sign of impending preterm birth.
Another evaluated fetal fibronectin, a glue-like protein that secures the amniotic sac to the inside of the uterus. Some studies have suggested that the presence of fetal fibronectin in the vagina early in pregnancy could signal early labor.
After screening more than 9,000 women who hadn't previously given birth, each test identified only a small proportion of the women who would eventually deliver preterm, the researchers said.
"What we found is that neither of these tests is very accurate," said lead author Sean Esplin, maternal-fetal medicine specialist at Intermountain Medical Center in Salt Lake City and professor of obstetrics-gynecology at the University of Utah School of Medicine.
"In a low-risk population, if we rely only on these tests to identify women who are highest risk, we're going to miss the vast majority."