a Women with first or second consecutive threatened spontaneous abortion in the first trimester. Published in Bulgarian; additional details not available in English abstract.
b Women with single intrauterine pregnancy with live embryo at 6 to <9 weeks’ gestation and vaginal bleeding, with/without abdominal pain, with closed cervix, and no history of recurrent miscarriage.
c Women with single intrauterine pregnancy at 6–10 weeks’ gestational age and vaginal bleeding, and no history of recurrent miscarriage (≥ 3 consecutive miscarriages).
bd = twice daily; DYD = dydrogesterone; N = number; NMP = natural micronised progesterone; OL = open-label; N = number of subjects; RCT = randomised controlled trial; RET = retrospective.
Table 3. Studies evaluating oral natural micronised progesterone for prevention of preterm birth.