Our objective was to determine whether obstetric history affects the efficacy of therapeutic cerclage. Data were gathered prospectively on patients receiving therapeutic cerclage, defined as midtrimester presentation with a cervical length less than 2.5 cm and prior preterm delivery or cervical dilatation with visible membranes on sterile speculum exam. Delivery outcomes based on cerclage type were compared between women with (n = 31) vs without prior term birth (n = 33). Patients with a history of a term birth were older than those without such history (P = .05) but otherwise similar with regard to ethnicity, body mass index, prior preterm birth, genitourinary infection, prior cervical surgery, gestational age at cerclage placement, and cerclage indication. Women with a therapeutic cerclage and a history of a prior term delivery were significantly more likely to deliver after 35 weeks (90% vs 48%, P < .001) and their babies were significantly larger (2942 +/- 812 g vs 1966 +/- 1069 g, P < .001) than women with no prior term delivery. Patients who develop cervical insufficiency after a term delivery may have better perinatal outcomes following therapeutic cerclage than those without a history of term delivery.