TABLE 4.

Description of 4 randomized studies with oral progesterone in preterm birth prevention that were excluded from metaanalysis

	Randomized trial
Characteristic	Noblot et al, 199122	Ndoni et al, 201020	Choudhary et al, 201421	Pustotina, 201823
Methods	Double blind randomized controlled trial	Randomized control study	Double blind randomized controlled trial	Randomized trial, open label with crossover after 1 week of therapy in randomized assignment
Location	France	Albania	India	Russia
Sample size	44	121	90	95
Inclusion criteria	Pregnant patients (including multiples) underwent tocolytic therapy for threated preterm labor; patients with preterm premature rupture of membranes at <32 wks gestation or previous tocolytic therapy excluded	Pregnant patients hospitalized at high risk for preterm delivery	Singletons at 24–34 wks Singleton gestation, cervical length ≤25 mm with or without symptoms of preterm labor/miscarriage (60 symptomatic at randomization)
Oral progesterone dose	400 mg every 6 hrs for 24 hrs, every 8 hrs for 24 hrs, 300 mg every 8 hrs daily; micronized progesterone (Utrogestan)	Dose not specified, micronized oral progesterone (Utrogestan)	200 mg micronized progesterone daily	Oral progesterone 400 mg daily
Comparator	Placebo	Daily 17 hydroxy-progesterone caproate and placebo	Placebo	17OHP 250 mg intramuscularly weekly OR vaginal progesterone 400 mg daily OR dydrogesterone 30 mg daily
Gestational age range at randomization	<35 Wks	15–22 Wks	24–64 Wks	15–24 Wks
Primary outcome	Latency to delivery: not different between groups	Not specified (abstract only), preterm labor and perinatal outcomes reported as improved in 17OHPC and oral progesterone vs placebo, but not compared with each other	Latency to delivery: improved in oral progesterone vs placebo	Not specified; oral progesterone not directly compared with other formulations