What do systematic reviews say?

Metformin vs placebo

Metformin showed no clear difference in gestational hypertension compared with placebo (low certainty).

• Metformin for women who are overweight or obese during pregnancy for improving maternal and infant outcomes 2018 · Cochrane Headline outcomes only
  RR 1.02 [0.54, 1.94]
  3 studies · 1040 participants
  Low