What do systematic reviews say?

Any supplements containing iron vs same supplements without iron or no treatment/placebo (no iron or placebo)

• Daily oral iron supplementation during pregnancy 2015 · Cochrane Headline outcomes only
  no estimate extracted
  15 studies · 18590 participants
  Moderate

Any supplements containing iron and folic acid vs same supplements without iron nor folic acid (no iron nor folic acid or placebo)

• Daily oral iron supplementation during pregnancy 2015 · Cochrane Headline outcomes only
  no estimate extracted
  2 studies · 1365 participants
  Moderate

Any supplements containing iron vs same supplements without iron or no treatment/placebo (no iron or placebo)

(Infant outcomes) Any supplements containing iron showed no clear difference in low birthweight (less than 2500 g) (ALL) compared with same supplements without iron or no treatment/placebo (no iron or… (low certainty).

• Daily oral iron supplementation during pregnancy 2015 · Cochrane Headline outcomes only
  RR 0.84 [0.69, 1.03]
  11 studies · 17613 participants
  Low

Any supplements containing iron and folic acid vs same supplements without iron nor folic acid (no iron nor folic acid or placebo)

(Infant outcomes) Any supplements containing iron and folic acid showed no clear difference in low birthweight (less than 2500 g) (ALL) compared with same supplements without iron nor folic acid (no iron nor folic acid… (low certainty).

• Daily oral iron supplementation during pregnancy 2015 · Cochrane Headline outcomes only
  RR 1.07 [0.31, 3.74]
  2 studies · 1311 participants
  Low