Neither 17α-hydroxyprogesterone caproate nor vaginal progesterone is useful for maintenance tocolysis in women with short cervix.

Intravaginal or Intramuscular progesterone used as maintenance therapy did not prolong pregnancy in women with arrested preterm labor and short cervix, reports a study published in July issue of Journal Obstetrics and Gynecology. 

   

This was a randomized, multi-center trial, conducted at five University hospitals  at University of Modena and Reggio Emilia, Italy across a period of 5 years. The researchers recruited 257 women between 22 0/7 and 31 6/7 weeks of gestation, who had a previous episode of preterm labor that responded well to tocolytics.

Other demographics were similar between the study participants.

All these women had short cervical length of 25 mm or less. The women were randomized to three groups to receive 200 mg of vaginal progesterone or 341 mg per week of intramuscular 17α-hydroxyprogesterone caproate or to an observation group.

The researchers were looking at number of preterm births averted due to use of vaginal or intramuscular progesterone.

Interim analysis was triggered after a specific percentage of preterm labor were observed, and the trial was stopped for futility. A P value of <.025 was defined as statistically significant.

After statistical analysis, it was found that progesterone was not efficient in prolonging pregnancy. 23% of women in 17α-hydroxyprogesterone caproate group had preterm births as compared to 22% in the control group (P=.949).

39% of women who was treated with vaginal progesterone underwent preterm labor as compared to 22% in the control group (P=.027).

The authors concluded that progesterone administered by either route did not prevent preterm labor in women with arrested incidence of preterm labor and short cervix.