Evaluation of adjunctive low-dose aspirin after non-prophylactic cerclage on the prevention of spontaneous preterm birth in singleton pregnancy: a nonrandomized controlled trial

Abstract

Background: Cervical cerclage cannot guarantee a full-term delivery. Recently, several studies have suggested that low-dose aspirin taken in pregnancy may reduce the likelihood of spontaneous preterm birth (sPTB). Our study aimed to evaluate whether adjunctive low-dose aspirin after non-prophylactic cerclage would reduce the rate of sPTB and improve pregnancy outcomes. Methods: A prospective clinical trial was conducted between September 2020 and July 2023 at two Tertiary A hospitals in Zhejiang Province, China. Singleton pregnancies with asymptomatic cervical dilation or cervical shortening and arranged non- prophylactic cerclage at 16–26 gestational weeks were included. Eligible women were assigned into either aspirin + regular therapy (Aspirin group) or only regular therapy group (No-aspirin group) based on their discretion. Propensity score matching was used to control confounding. The primary outcome was the incidence of sPTB at < 28 weeks of gestation. Results: A total of 230 women underwent cervical cerclage with extra aspirin therapy (n = 83) or regular therapy (n = 147) were identified. Overall, all participants were 1:1 propensity score-matched with 75 in Aspirin group and 75 in No-aspirin group. The rates of sPTB at < 28 and < 32 weeks were significantly lower in Aspirin group than in No-aspirin group. A greater proportion of pregnancies were prolonged at least 28 days and 56 days among women received additional aspirin than regular therapy. The overall perinatal mortality was significantly lower in Aspirin group (2.67%) than in No-aspirin group (17.33%) (p < 0.01). In ultrasound-indicated cerclage, the incidence of sPTB at < 32 weeks was significantly lower in Aspirin group, whereas in physical- indicated cerclage, it did not reach a significate difference. Conclusion: We indicated that the administration of low-dose aspirin in singleton pregnancies after non-prophylactic cerclage was associated with a significant decrease in extremely preterm birth. Trial registration: The study was registered in the Chinese Clinical Trial Registry with a registration number of ChiCTR2000034662 at 2020-07-13 (https://www.chictr.org.cn/).