We sought to estimate the effect of indomethacin on duration of pregnancy in women with dilated cervix between 140/7 to 256/7 weeks. Demographics, risk factors, and outcomes were compared in women 146/7 to 256/7 weeks with a dilated cervix >= 1 cm who received indomethacin versus no indomethacin therapy, stratified for cerclage. Primary outcome was interval from presentation until delivery. Of 222 singleton gestations, 68 (31%) received indomethacin. In unadjusted and adjusted analyses, no significant differences were observed in interval from presentation to delivery and preterm birth < 28, < 32, or < 35 weeks comparing the indomethacin and no indomethacin groups, even after stratification for cerclage. In multivariate logistic regression analysis limited to women receiving cerclage, preterm birth < 32 weeks (odds ratio 0.56, 95% confidence interval 0.26, 1.25) and < 35 weeks (odds ratio 0.52, 95% confidence interval 0.23, 1.14) suggested a possible but not significant benefit for indomethacin use. Indomethacin therapy in women with dilated cervix at 140/7 to 256/7 weeks, regardless of cerclage or not, had no effect on pregnancy outcomes.