In women with a multiple pregnancy, spontaneous pre‐term delivery is the leading cause of perinatal morbidity and mortality. Interventions to reduce pre‐term birth in these women have not been successful (at the time of writing). The Kaplan– Meier curves in Figure 25.9 are from a randomised controlled trial to assess whether a cervical pessary could effectively prevent poor perinatal outcomes. The women, with a multiple pregnancy between 12 and 20weeks’ gestation, were randomly assigned to pessary or control groups. The top curves are for women with a cervical length of less than 38mm, the bottom curves for women with a cervical length of at least 38mm. What does the log‐rank test indicate about the comparable survival experience of the women with shorter and longer cervixes?
