What do systematic reviews say?

Metformin vs clomiphene

Metformin showed no clear difference in miscarriage rate per woman aParticipants with BMI < 30 kg/2 compared with clomiphene citrate (low certainty).

• Metformin for ovulation induction (excluding gonadotrophins) in women with polycystic ovary syndrome 2019 · Cochrane Headline outcomes only
  OR 1.51 [0.62, 3.71]
  4 studies · 281 participants
  Low