Comparison 2. Supplementation with vitamin D + calcium versus placebo or no intervention (no vitamin or minerals).

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Pre‐eclampsia (ALL)	4	1174	Risk Ratio (M‐H, Random, 95% CI)	0.50 [0.32, 0.78]
2 Gestational diabetes (ALL)	1	54	Risk Ratio (M‐H, Random, 95% CI)	0.33 [0.01, 7.84]
3 Preterm birth (less than 37 weeks' gestation) (ALL)	5	942	Risk Ratio (M‐H, Random, 95% CI)	1.52 [1.01, 2.28]
4 Low birthweight (less than 2500 g) (ALL)	2	110	Risk Ratio (M‐H, Random, 95% CI)	0.68 [0.10, 4.55]
5 Caesarean section	2	146	Risk Ratio (M‐H, Random, 95% CI)	1.16 [0.87, 1.54]
6 Gestational hypertension	1	59	Risk Ratio (M‐H, Random, 95% CI)	0.26 [0.06, 1.12]
7 Maternal vitamin D concentration at term (25‐hydroxyvitamin D) (nmol/L) (ALL)	1	60	Mean Difference (IV, Random, 95% CI)	12.5 [3.80, 21.20]
8 Birth length (cm)	3	194	Mean Difference (IV, Random, 95% CI)	‐0.07 [‐0.67, 0.52]
9 Head circumference at birth (cm)	3	198	Mean Difference (IV, Random, 95% CI)	‐0.03 [‐0.39, 0.33]
10 Birthweight (g)	3	194	Mean Difference (IV, Random, 95% CI)	42.39 [‐86.96, 171.74]
11 Neonatal death	1	660	Risk Ratio (M‐H, Random, 95% CI)	0.2 [0.01, 4.15]