17-alpha-hydroxyprogesterone caproate versus vaginal progesterone suppository for the prevention of preterm birth in women with a sonographically short cervix: A randomized controlled trial.

Aim: The aim of this study was to compare 17-alpha-hydroxyprogesterone caproate (17OHP-C) with vaginal progesterone suppository for the prevention of preterm birth in women with a sonographically short cervix and to evaluate the changes of the cervical length (CL) over time.

Methods: In this prospective randomized controlled trial, eligible patients were asymptomatic pregnant women with a sonographically short cervix. The participants in group 1 (n = 147) received vaginal progesterone suppositories at a dose of 400 mg daily and the women in group 2 (n = 150) received an i.m. dose of 250 mg 17OHP-C once a week. Transvaginal sonography was repeated every 3 weeks until 36 gestational weeks or the occurrence of preterm labor.

Results: A total of 304 singleton pregnant women between 16 and 24 gestational weeks with CL < 25 mm were enrolled in our study. The rates of preterm birth were 10.4% in the progesterone group and 14% in the 17OHP-C group: a difference that was not statistically significant (P = 0.416). Moreover, 264 participants underwent ultrasound examination five times and CL changes were studied for 15 weeks. The results showed that the CL changes over 15 weeks were statistically significant (P < 0.001), but the method of intervention (progesterone/17OHP-C) had no significant effect on CL change (P = 0.64).

Conclusion: Our findings showed that vaginal progesterone and 17OHP-C had the same effect on the risk of preterm labor in asymptomatic women with a sonographically short cervix. We detected no significant difference between the effect of 17OHP-C and vaginal progesterone on CL changes over time.