Preterm premature rupture of membranes (PPROM) is a condition leading to an 
increased risk of maternal and neonatal morbidity and mortality in pregnant 
women. To prevent this complication, some studies have proposed using 
prophylactic progesterone. However, due to lack of sufficient relevant data, 
there is still need for further studies in this regard. This study was performed 
to determine the effect of rectal progesterone on the latent phase and maternal 
and neonatal outcome variables in females with PPROM. During the present 
randomized clinical trial study (IRCT201512077676N4), a total of 120 patients 
with PPROM at pregnancy ages between 26 and 32 weeks were randomly assigned to 2 
equal intervention and control groups. In the intervention group, progesterone 
suppositories (400 mg per night) were administered until delivery or completion 
of the 34th gestational week and was compared with placebo effect in control 
group. The latent phase and maternal and neonatal outcome variables were 
compared between the two groups. The mean age of patients was 29.56±5.66 (19-42) 
and 29.88±5.57 (17-40) years in the intervention and control group, 
respectively. The two groups were almost identical in the confounding factors. 
The median latent phase was 8.5 days in the intervention group vs. 5 days in the 
control group in the 28th-30th weeks of gestation, which was significantly 
higher in the intervention group (P=0.001). Among maternal and neonatal outcome 
variables, only the mean birth-weight was significantly higher in the 
intervention group than that in the controls (1609.92±417.28 gr vs. 
1452.03±342.35 gr, P=0.03). Administration of progesterone suppository in 
patients with PPROM at gestational ages of 28 to 30 weeks is effective in 
elongating the latent phase and increasing birth-weight with no significant 
complications.