One of the key indicators of a nation’s health is how well it can care for its young. Despite many advances in medical care and improvements in access to care, infant mortality remains a significant concern worldwide. According to the World Health Organization , the leading cause of death among children under age 5 is preterm birth complications. With an estimated 15 million babies born prematurely (prior to 37 weeks’ gestation) globally each year, it is vital for ob.gyns. to uncover ways to predict, diagnose early, and treat the causes of preterm birth.

While the challenges to infant health could be considered more of an issue in developing countries, here in the United States, the Centers for Disease Control and Prevention estimates that 1 in 9 babies is born prematurely. Preterm birth-related causes of death (i.e., breathing and feeding problems and disabilities) accounted for 35% of all infant deaths in 2010.

Dr. E. Albert Reece

The World Health Organization (WHO) lists the United States as one of the top 10 countries with the greatest number of preterm births, despite the fact that we spend approximately 17.1% of our gross domestic product in total health care expenditures – the highest rate among our peer nations.

In the April 2014 edition of Master Class , we discussed one of the primary causes of preterm birth, bacterial infections, and specifically the need for ob.gyns. to rigorously screen patients for asymptomatic bacteriuria, which can lead to pyelonephritis. This month, we examine another biologic marker of preterm birth, cervical length.

Seminal studies of transvaginal sonography to measure cervical length during pregnancy and predict premature birth were published more than 2 decades ago. This work showed that a short cervix at 24 and 28 weeks’ gestation predicted preterm birth. Since then, clinical studies have demonstrated the utility of cervical length screening in women with prior preterm pregnancies. In the last decade, three large, randomized human trials have examined the usefulness of universal cervical length screening ( Am. J. Obstet. Gynecol. 2012;207:101-6 ). However, the results of these trials have given practitioners a confusing picture of the predictability of this biologic marker.

Given the complexity of the “to screen or not to screen” issue, we have devoted this Master Class to a discussion on the role of cervical length screening and the prediction of preterm birth. Our guest author this month is Dr. Erika Werner, an assistant professor in ob.gyn (maternal-fetal medicine) in the department of obstetrics and gynecology at Brown University, in Providence, R.I., and an expert in the area of preterm birth.

Dr. Reece, who specializes in maternal-fetal medicine, is vice president for medical affairs at the University of Maryland, Baltimore, as well as the John Z. and Akiko K. Bowers Distinguished Professor and dean of the school of medicine. Dr. Reece said he had no relevant financial disclosures. He is the medical editor of this column. Contact him at [email protected].