What do systematic reviews say?

Wheat flour or wheat flour products fortified with folic acid plus other vitamins and minerals vs unfortified wheat flours or wheat flour products (not containing folic acid nor any other vitamins and minerals)

It is very uncertain whether wheat flour or wheat flour products fortified with folic acid plus… changes anaemia compared with unfortified wheat flours or wheat flour products (not containing… (very low certainty).

• Fortification of wheat and maize flour with folic acid for population health outcomes 2019 · Cochrane Headline outcomes only
  RR 0.87 [0.68, 1.11]
  657 participants
  Very low

Wheat flour or wheat flour products fortified with folic acid plus other vitamins and minerals vs unfortified wheat flours or wheat flour products (not containing folic acid nor any other vitamins and minerals)

Wheat flour or wheat flour products fortified with folic acid plus… showed no clear difference in anaemia compared with unfortified wheat flours or wheat flour products (not containing… (low certainty).

• Fortification of wheat and maize flour with folic acid for population health outcomes 2019 · Cochrane Headline outcomes only
  RR 1.07 [0.74, 1.55]
  1 study · 334 participants
  Low

Any intermittent iron regimen (with or without other vitamins and minerals) vs daily regimen (with same vitamins and minerals)‐maternal outcomes

It is very uncertain whether any intermittent iron regimen (with or without other vitamins and… changes maternal anaemia at term (Hb less than 110 g/L at 37 weeks'… compared with daily regimen (with same vitamins and minerals)‐maternal outcomes (very low certainty).

• Intermittent oral iron supplementation during pregnancy 2015 · Cochrane Headline outcomes only
  RR 1.22 [0.84, 1.8]
  4 studies · 676 participants
  Very low

Any intermittent iron regimen (with or without other vitamins and minerals) vs daily regimen (with same vitamins and minerals)‐maternal outcomes

• Intermittent oral iron supplementation during pregnancy 2015 · Cochrane Headline outcomes only
  no estimate extracted
  6 studies · 1240 participants
  Very low

Any intermittent iron regimen (with or without other vitamins and minerals) vs daily regimen (with same vitamins and minerals)‐maternal outcomes

It is very uncertain whether any intermittent iron regimen (with or without other vitamins and… changes maternal iron‐deficiency anaemia at term (Hb less than 110 g/L and… compared with daily regimen (with same vitamins and minerals)‐maternal outcomes (very low certainty).

• Intermittent oral iron supplementation during pregnancy 2015 · Cochrane Headline outcomes only
  RR 0.71 [0.08, 6.63]
  1 study · 156 participants
  Very low

Provision of maize flour or maize flour products fortified with iron plus other vitamins and minerals vs unfortified maize flours or maize flour products

It is very uncertain whether provision of maize flour or maize flour products fortified with iron… changes anaemia (defined as haemoglobin (Hb) below WHO cut‐off, adjusted for… compared with unfortified maize flours or maize flour products (very low certainty).

• Fortification of maize flour with iron for controlling anaemia and iron deficiency in populations 2018 · Cochrane Headline outcomes only
  RR 0.9 [0.58, 1.4]
  2 studies · 1027 participants
  Very low