Serial transvaginal cervical length measurements and quantitative vaginal fetal fibronectin concentrations did not predict spontaneous preterm birth in low-risk nulliparous women.

Commentary on: Esplin MS, Elovitz MA, Iams JD, et al . Predictive accuracy of serial transvaginal cervical lengths and quantitative vaginal fetal fibronectin levels for spontaneous preterm birth among nulliparous women. JAMA 2017;317:1047–1056. Approximately 10% of pregnancies in the USA are delivered preterm, with two-thirds being spontaneous.1 While the single greatest risk factor for preterm birth (PTB) is a history of PTB, about 40% of pregnancies occur in nulliparous women. Identifying nulliparas who are most at risk for spontaneous PTB would allow for new approaches to lower the PTB rate. Two strategies have been promoted to identify women at high risk for PTB, including serial cervical length (CL) measurements and quantitative fetal fibronectin (FFN) concentrations. A short cervix has been shown to place women with a prior PTB at high risk for subsequent PTB …