comparison of risk of preterm labor between vaginal progesterone and17-alpha-hydroxy-progesterone caproate in women with threatened abortion: a randomized clinical trial

objective: threatened miscarriage is a common complication in pregnancy that leads to adverse pregnancy outcomes such as preterm labor. this study aimed to compare the vaginal progesterone (cyclogest) versus 17-alpha-hydroxyprogesterone caproate (proluton) on preventing preterm labor in pregnant women with threatened abortion at less than 34 weeks’ gestational age. materials and methods: this balanced randomized, double-blind, single-center controlled clinical trial included 190 women with threatened abortion. they were then randomly allocated into cyclogest (n=95) and 17-alpha-hydroxyprogesterone caproate (proluton, n=95) groups. interested outcome was preterm labor less than 34 weeks. the pearson chi-square and student’s t test were used to compare two groups. the data were analyzed by stata software version 13. results: the risks of preterm labor less than 34 weeks in proluton and cyclogest groups were 8.6 and 6.52%, respectively. there was no significant difference for risk of preterm labor less than 34 weeks [relative ratio (rr): 1.31, 95% confidence interval (ci): 0.47- 3.66, p=0.59] between two groups. conclusion: risk of preterm labor in the vaginal progesterone group and 17-alpha-hydroxyprogesterone caproate group in pregnant women with threatened abortion is the same (registration number: irct2014123120504n1).