Vitamin D supplementation probably leads to lower low birthweight (less than 2500 g) compared with placebo or no intervention (moderate certainty).
Vitamin D + calcium supplementation probably leads to lower pre‐eclampsia compared with placebo or no intervention (moderate certainty).
It is very uncertain whether vitamin D + calcium supplementation changes gestational diabetes compared with placebo or no intervention (very low certainty).
Calcium supplementation showed no clear difference in pre‐eclampsia compared with placebo (maternal outcomes) commencing before or early (low certainty).
Calcium supplementation showed no clear difference in pre‐eclampsia, or pregnancy loss, or stillbirth (or combination) at… compared with placebo (maternal outcomes) commencing before or early (low certainty).
Calcium supplementation showed no clear difference in severe maternal morbidity and mortality index compared with placebo (maternal outcomes) commencing before or early (low certainty).
Calcium supplementation showed no clear difference in pregnancy loss or stillbirth at any gestational age compared with placebo (maternal outcomes) commencing before or early (low certainty).
Calcium supplementation showed no clear difference in caesarean section compared with placebo (maternal outcomes) commencing before or early (low certainty).
Calcium showed no clear difference in birthweight < 2500 g compared with placebo (offspring outcomes) commencing before or early (low certainty).
It is very uncertain whether calcium changes apgar < 7 at 5 minutes compared with placebo (offspring outcomes) commencing before or early (very low certainty).
Calcium showed no clear difference in perinatal death, or NICU admission for > 24 hours (or both) compared with placebo (offspring outcomes) commencing before or early (low certainty).
Calcium showed no clear difference in pregnancy loss, stillbirth or NND before discharge compared with placebo (offspring outcomes) commencing before or early (low certainty).
Intramuscular (IM) progesterone showed no clear difference in perinatal death compared with no treatment or placebo (low certainty).
Vaginal progesterone showed no clear difference in infant birthweight less than 2500 g compared with no treatment or placebo (moderate certainty).
Vaginal progesterone showed no clear difference in preterm birth less than 37 weeks compared with no treatment or placebo (moderate certainty).
Vaginal progesterone showed no clear difference in preterm birth less than 28 weeks compared with no treatment or placebo (low certainty).
Intramuscular (IM) progesterone may leads to higher preterm birth less than 34 weeks compared with no treatment or placebo (low certainty).
Intramuscular (IM) progesterone showed no clear difference in infant birthweight less than 2500 g compared with no treatment or placebo (moderate certainty).
Intramuscular (IM) progesterone showed no clear difference in preterm birth less than 28 weeks compared with no treatment or placebo (moderate certainty).