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.