Saade GR, et al. - This study is designed to determine whether the presence of cervical funneling or intra-amniotic debris identified in the second trimester is associated with higher rates of preterm birth (PTB) in asymptomatic nulliparous women with a midtrimester cervical length (CL) less than 30 mm (i.e., less than the 10th percentile). It was observed that the presence of intra-amniotic debris, but not a cervical funnel, is associated with increased risk of PTB < 34 weeks of gestation among asymptomatic nulliparous women with a midtrimester cervical length less than 30 mm. This association was independent of the CL.