Antepartum uterine activity characteristics differentiating true from threatened preterm labor.

Daily antepartum nursing contact and ambulatory uterine activity monitoring have been used for the early detection of preterm labor. However, it may be difficult to separate true labor from false labor. In this study, the uterine activity records of 110 women at risk for preterm birth with excessive contraction frequencies were evaluated by blinded reviewers. Maternal symptomatology and uterine activity characteristics such as low-amplitude high-frequency contractility, contraction amplitude, contraction duration, contraction interval, and contraction rhythmicity were assessed for their ability to differentiate true from threatened preterm labor. Neither maternal symptomatology nor any uterine activity characteristic other than contraction frequency could differentiate true from threatened preterm labor. Antepartum uterine activity monitoring should continue to rely on contraction frequency to identify the woman at risk for premature labor.