Does Intramuscular Progesterone Help Women With Prior Preterm Birth Screened for Ultrasound-Indicated Cerclage? [25K

Abstract

INTRODUCTION: Weekly intramuscular 17α-hydroxyprogesterone caproate (17P) is endorsed by the American College of Obstetricians and Gynecologists for recurrent preterm birth (PTB) prevention. Cerclage is indicated in patients with prior PTB and a midtrimester cervical length (CL) less than 25 mm. We aimed to assess if these two preventive strategies, when combined, confer additive benefit in prolonging gestation. METHODS: Retrospective cohort of all singletons delivered at a single center that underwent CL screening from 2011 to 2016 for prior PTB. Exposure was any 17P use. Primary outcome was gestational age (GA) at delivery. Secondary outcomes included cerclage, preterm labor (PTL) admission, and preterm premature rupture of membranes (PPROM). ANCOVA was used to assess the relationship between 17P and delivery GA, controlling for cerclage, initial CL, number of prior PTB, and GA of earliest prior PTB. RESULTS: Of 409 patients who underwent CL screening, 293 received 17P (group 17P), and 116 did not. Groups did not differ by age, race, BMI, payer, number of prior PTB, or initial CL. GA of earliest prior PTB was lower in group 17P (27.4 vs 29.9 weeks; P < .001). Delivery GA occurred earlier in group 17P (35.7 vs 37.2 weeks; P=.002). Group 17P also had higher rates of PPROM (22.2% vs 11.2%; P=.011), PTL admission (42% vs 25%; P=.001), and cerclage (18.1% vs 5.2%; P < .001). After controlling for confounders, delivery GA remained significantly lower in group 17P (34.9 vs 35.9 weeks; P=.027). CONCLUSION: In a population with prior PTB followed with CL screening and ultrasound-indicated cerclage, 17P did not prolong gestation.