Boelig RC, Kripalu V, Chen SL, et al. - A protocol for serial cervical length screening has been studied and recommended in women with a prior preterm birth, for identification and treatment of short cervix. Researchers here aimed at ascertaining the value of follow up cervical length screening in otherwise low risk singletons with a mid-trimester cervical length measurement of 26-29mm through evaluation of the rate of short cervix (≤ 25mm) on follow up ultrasound and subsequent delivery outcomes. At a single urban institution, they conducted a 3 year retrospective cohort study of pregnant singletons, with no prior spontaneous preterm birth, and an initial transvaginal ultrasound cervical length measurement of 26-29mm recognized during universal cervical length screening at time of anatomy ultrasound (18 0/7 -22 6/7 weeks). During the study period, a total of 2,801 singletons 18 0/7 – 22 6/7 weeks were identified with transvaginal cervical length ultrasound at time of anatomy scan; of these, they included 201 having a CL 26-29mm, and 184 (7%) with no prior spontaneous preterm birth. Findings suggest that cervical shortening ≤ 25mm prior to 24weeks is experienced by nearly 15% of low risk singletons with a mid-trimester cervical length measurement of 26-29mm. Significantly higher rate of spontaneous preterm birth (16%) was observed in women with an initial CL 26-29mm and subsequent shortening ≤ 25mm than would be expected for a cohort of singletons without a history of preterm birth. One early preterm birth < 34 weeks would be prevented by performing 111 additional follow up cervical length ultrasounds.