What do systematic reviews say?

Progesterone vs placebo/no treatment

Progesterone showed no clear difference in miscarriage rate per clinical pregnancy compared with placebo/no treatment (low certainty).

• Luteal phase support for women trying to conceive by intrauterine insemination or sexual intercourse 2022 · Cochrane Headline outcomes only
  RR 0.68 [0.24, 1.91]
  2 studies · 102 participants
  Low