Progesterone for prevention of preterm birth
Most studies of progesterone in prevention of preterm birth concerned 2 target groups:
1) pregnant women with previous preterm birth and
2) the women with short cervix during mid-trimester.
Most studies used either intramuscular or vaginal progesterone for the prevention of preterm birth.
Only few studies with small number of cases used oral progesterone.
So, we do not include oral progesterone in this review