Figure 1.

Overview of investigated strategies for prevention of spontaneous preterm delivery (sPTD) in asymptomatic women with a singleton pregnancy, based on sonographic cervical length (CL) screening and vaginal progesterone treatment, when CL is measured by transvaginal ultrasound at: (a) 18 + 0 to 20 + 6 weeks, on the day of the routine fetal scan (Cx1); and (b) 21 + 0 to 23 + 6 weeks, at an additional appointment (Cx2). The decision analytic model was constructed as a combined decision‐tree model (screening year) and a Markov model with three health states (healthy, long‐term morbidity or death) conducted with annual cycles for a time horizon of 100 years.