Does combination treatment with progesterone and vaginal cervical cerclage improve pregnancy outcomes in women at high risk of preterm birth? A retrospective, secondary analysis of the C-STICH suture thread for cerclage trial data

BackgroundVaginal cervical cerclage and progesterone are established treatments for prevention of pregnancy loss and prematurity. There is limited data to assess the effect of these treatments in combination. ObjectiveTo investigate the association between progesterone and no progesterone treatment on pregnancy outcomes in women at high risk of preterm birth who have received a vaginal cervical cerclage. Study DesignThis is a secondary analysis of women recruited to the CSTICH trial, which recruited in 75 obstetric units in the UK. The primary outcome was pregnancy loss, defined as miscarriage and perinatal mortality, including any stillbirth or neonatal death in the first week of life. Secondary maternal outcomes included miscarriage and previable neonatal death; stillbirth; gestational age at delivery; preterm pre labour rupture of membranes and sepsis. Secondary neonatal outcomes included early/late neonatal death and sepsis. For each outcome, regression models were fitted adjusting for pre-specified prognostic variables. Results1943 women had a vaginal cerclage placed, with available progesterone data. From the 2048 women recruited to CSTICH; 843 (43%) women received progesterone and 1109 (57%) did not receive progesterone. Pregnancy loss occurred in 49 (5.9%) of 832 women who received progesterone and 91 (8.3%) of 1103 women who did not receive progesterone (adjusted risk ratio 0.70, 95% confidence interval (CI): 0.50 to 0.99; adjusted risk difference - 0.02, 95% CI: -0.04 to -0.001). ConclusionThere appears to be an association with progesterone use in women who receive a vaginal cervical cerclage and a reduction in pregnancy loss. This combination therapy may be an important opportunity to further reduce the risk of pregnancy loss in this high risk cohort.