Vitamin C and vitamin E showed no clear difference in any adverse effects of vitamin supplementation sufficient to stop… compared with placebo (moderate certainty).
Vitamin C and vitamin E showed no clear difference in total fetal loss compared with placebo (high certainty).
Vitamin C and vitamin E showed no clear difference in early or late miscarriage compared with placebo (moderate certainty).
Vitamin C and vitamin E showed no clear difference in stillbirth compared with placebo (moderate certainty).
It is very uncertain whether summary of findings table ‐ Vitamin B12 supplementation changes maternal vitamin B12 deficiency compared with placebo/no vitamin B12 supplementation (very low certainty).
Vitamin A plus iron plus folate showed no clear difference in total fetal loss (including miscarriages or combined miscarriages… compared with iron plus folate (low certainty).
Vitamin A plus iron plus folate showed no clear difference in early or late miscarriage ‐ Vitamin A + iron + folate versus iron +… compared with iron plus folate (low certainty).
Vitamin A plus iron plus folate showed no clear difference in stillbirth ‐ Vitamin A + iron + folate versus iron + folate compared with iron plus folate (low certainty).
Multivitamin plus iron plus folate showed no clear difference in early or late miscarriage ‐ Multivitamin + iron + folic acid versus… compared with iron plus folate (moderate certainty).
Multivitamin plus iron plus folate leads to lower stillbirth ‐ Multivitamin + iron + folic acid versus iron + folic acid compared with iron plus folate (high certainty).
Multivitamin plus iron plus folate showed no clear difference in total fetal loss (including miscarriages or combined miscarriages… compared with iron plus folate (high certainty).
Any vitamin E supplementation showed no clear difference in stillbirth compared with placebo, no placebo or other supplements (moderate certainty).
Any vitamin E supplementation showed no clear difference in preterm birth (less than 37 weeks' gestation) compared with placebo, no placebo or other supplements (high certainty).
Any vitamin E supplementation showed no clear difference in clinical pre‐eclampsia (random‐effects model) compared with placebo, no placebo or other supplements (moderate certainty).
Any vitamin E supplementation showed no clear difference in intrauterine growth restriction (various definitions) compared with placebo, no placebo or other supplements (high certainty).
Any vitamin E supplementation showed no clear difference in prelabour rupture of fetal membranes ‐ preterm compared with placebo, no placebo or other supplements (low certainty).
Any vitamin E supplementation leads to lower bleeding episodes (placental abruption) compared with placebo, no placebo or other supplements (high certainty).
It is very uncertain whether vitamin D + calcium + other vitamins and minerals changes gestational diabetes compared with calcium + other vitamins and minerals (but no vitamin D) (very low certainty).