Comparison 1. Routine high‐dose calcium supplementation in pregnancy by baseline dietary calcium.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 High blood pressure (with or without proteinuria)	12	15470	Risk Ratio (M‐H, Random, 95% CI)	0.65 [0.53, 0.81]
1.1 Adequate calcium diet	4	5022	Risk Ratio (M‐H, Random, 95% CI)	0.90 [0.81, 0.99]
1.2 Low calcium diet	7	10418	Risk Ratio (M‐H, Random, 95% CI)	0.44 [0.28, 0.70]
1.3 Dietary calcium not specified	1	30	Risk Ratio (M‐H, Random, 95% CI)	0.91 [0.57, 1.45]
2 Pre‐eclampsia	13	15730	Risk Ratio (M‐H, Random, 95% CI)	0.45 [0.31, 0.65]
2.1 Adequate calcium diet	4	5022	Risk Ratio (M‐H, Random, 95% CI)	0.62 [0.32, 1.20]
2.2 Low calcium diet	8	10678	Risk Ratio (M‐H, Random, 95% CI)	0.36 [0.20, 0.65]
2.3 Dietary calcium not specified	1	30	Risk Ratio (M‐H, Random, 95% CI)	0.14 [0.02, 1.02]
3 Preterm birth	11	15275	Risk Ratio (M‐H, Random, 95% CI)	0.76 [0.60, 0.97]
3.1 Adequate calcium diet	4	5033	Risk Ratio (M‐H, Random, 95% CI)	0.59 [0.26, 1.33]
3.2 Low calcium diet	7	10242	Risk Ratio (M‐H, Random, 95% CI)	0.81 [0.64, 1.02]
4 Admission to neonatal intensive care unit	4	13406	Risk Ratio (M‐H, Fixed, 95% CI)	1.05 [0.94, 1.18]
4.1 Adequate calcium diet	1	4336	Risk Ratio (M‐H, Fixed, 95% CI)	1.09 [0.95, 1.26]
4.2 Low calcium diet	3	9070	Risk Ratio (M‐H, Fixed, 95% CI)	0.98 [0.81, 1.19]
5 Stillbirth or death before discharge from hospital	11	15665	Risk Ratio (M‐H, Fixed, 95% CI)	0.90 [0.74, 1.09]
5.1 Adequate calcium diet	4	5033	Risk Ratio (M‐H, Fixed, 95% CI)	1.12 [0.66, 1.90]
5.2 Low calcium diet	7	10632	Risk Ratio (M‐H, Fixed, 95% CI)	0.86 [0.70, 1.07]
6 Maternal death/serious morbidity	4	9732	Risk Ratio (M‐H, Fixed, 95% CI)	0.80 [0.66, 0.98]
6.1 Low calcium diet	4	9732	Risk Ratio (M‐H, Fixed, 95% CI)	0.80 [0.66, 0.98]
6.2 Adequate calcium diet	0	0	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
7 Placental abruption	5	14336	Risk Ratio (M‐H, Fixed, 95% CI)	0.86 [0.55, 1.34]
7.1 Adequate calcium diet	3	4830	Risk Ratio (M‐H, Fixed, 95% CI)	0.81 [0.39, 1.68]
7.2 Low calcium diet	2	9506	Risk Ratio (M‐H, Fixed, 95% CI)	0.89 [0.51, 1.55]
8 Caesarean section	8	15234	Risk Ratio (M‐H, Fixed, 95% CI)	0.95 [0.89, 1.02]
8.1 Adequate calcium diet	3	4981	Risk Ratio (M‐H, Fixed, 95% CI)	0.95 [0.84, 1.07]
8.2 Low calcium diet	5	10253	Risk Ratio (M‐H, Fixed, 95% CI)	0.96 [0.88, 1.04]
9 Proteinuria (gestational with no proteinuria)	1	8312	Risk Ratio (M‐H, Fixed, 95% CI)	1.04 [0.86, 1.26]
9.1 Adequate calcium diet	0	0	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
9.2 Low calcium diet	1	8312	Risk Ratio (M‐H, Fixed, 95% CI)	1.04 [0.86, 1.26]
10 Severe pre‐eclampsia	1	8302	Risk Ratio (M‐H, Fixed, 95% CI)	0.74 [0.48, 1.15]
10.1 Adequate calcium diet	0	0	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
10.2 Low calcium diet	1	8302	Risk Ratio (M‐H, Fixed, 95% CI)	0.74 [0.48, 1.15]
11 Eclampsia	3	13425	Risk Ratio (M‐H, Fixed, 95% CI)	0.73 [0.41, 1.27]
11.1 Adequate calcium diet	1	4589	Risk Ratio (M‐H, Fixed, 95% CI)	1.00 [0.25, 3.99]
11.2 Low calcium diet	2	8836	Risk Ratio (M‐H, Fixed, 95% CI)	0.68 [0.37, 1.26]
12 HELLP syndrome	2	12901	Risk Ratio (M‐H, Fixed, 95% CI)	2.67 [1.05, 6.82]
12.1 Adequate calcium diet	1	4589	Risk Ratio (M‐H, Fixed, 95% CI)	3.50 [0.73, 16.82]
12.2 Low calcium diet	1	8312	Risk Ratio (M‐H, Fixed, 95% CI)	2.26 [0.70, 7.32]
13 Intensive care unit admission	1	8312	Risk Ratio (M‐H, Fixed, 95% CI)	0.84 [0.66, 1.07]
13.1 Adequate calcium diet	0	0	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
13.2 Low calcium diet	1	8312	Risk Ratio (M‐H, Fixed, 95% CI)	0.84 [0.66, 1.07]
14 Maternal death	1	8312	Risk Ratio (M‐H, Fixed, 95% CI)	0.17 [0.02, 1.39]
14.1 Adequate calcium diet	0	0	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
14.2 Low calcium diet	1	8312	Risk Ratio (M‐H, Fixed, 95% CI)	0.17 [0.02, 1.39]
15 Low birthweight (birthweight < 2500 g)	9	14883	Risk Ratio (M‐H, Random, 95% CI)	0.85 [0.72, 1.01]
15.1 Adequate calcium diet	4	5033	Risk Ratio (M‐H, Random, 95% CI)	0.59 [0.31, 1.13]
15.2 Low calcium diet	5	9850	Risk Ratio (M‐H, Random, 95% CI)	0.95 [0.85, 1.05]
16 Neonate small‐for‐gestational age as defined by trial authors	4	13615	Risk Ratio (M‐H, Fixed, 95% CI)	1.05 [0.86, 1.29]
16.1 Adequate calcium diet	1	4589	Risk Ratio (M‐H, Fixed, 95% CI)	1.18 [0.92, 1.52]
16.2 Low calcium diet	3	9026	Risk Ratio (M‐H, Fixed, 95% CI)	0.85 [0.60, 1.21]
17 Systolic blood pressure > 95th percentile during childhood	1	514	Risk Ratio (M‐H, Fixed, 95% CI)	0.59 [0.39, 0.91]
17.1 Adequate calcium diet	0	0	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
17.2 Low calcium diet	1	514	Risk Ratio (M‐H, Fixed, 95% CI)	0.59 [0.39, 0.91]
18 Diastolic blood pressure > 95th percentile during childhood	1	514	Risk Ratio (M‐H, Fixed, 95% CI)	0.81 [0.50, 1.31]
18.1 Adequate calcium diet	0	0	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
18.2 Low calcium diet	1	514	Risk Ratio (M‐H, Fixed, 95% CI)	0.81 [0.50, 1.31]
19 Dental caries in childhood	1	195	Risk Ratio (M‐H, Fixed, 95% CI)	0.73 [0.62, 0.87]
19.1 Low calcium diet	1	195	Risk Ratio (M‐H, Fixed, 95% CI)	0.73 [0.62, 0.87]