Preterm labor tests: current status and future directions.

Preterm labor (PTL) is a severe issue of neonatal healthcare because its related to preterm birth (PTB) is the leading cause of neonatal mortality and the most common reason for antenatal hospitalizations. The PTB rate is about 11% globally and it is similar in the United States. PTB poses a significant economic burden on the healthcare system. Early diagnosis of PTL is the key to reducing PTB rate, neonatal mortality, and long-term neurological impairment in children. The diagnosis of PTL is usually based on clinical criteria, but the accuracy of the diagnosis is poor. To predict the risk of PTL more accurately, tests of biomarkers with variable clinical diagnostic performances have been developed and some of them have been applied clinically. In this article, we analyze the performance characteristics of these biomarkers, such as sensitivity, specificity, positive predictive value, and negative predictive value, as well as the clinical utility of current biomarkers so that clinical laboratorians and clinicians can better understand the limitations of these tests and utilize them wisely. We also summarize the current recommendations on clinical utilization of PTL biomarkers. Finally, we explore the prospects of future omics-based novel biomarkers, which may improve prediction of PTL in the future.