Comparison 4. Vitamin A alone versus placebo or no treatment (subgroups).

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Perinatal mortality (infant mortality level)	1	76176	Risk Ratio (M‐H, Fixed, 95% CI)	1.01 [0.95, 1.07]
1.1 Countries with low infant mortality	0	0	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
1.2 Countries with high infant mortality	1	76176	Risk Ratio (M‐H, Fixed, 95% CI)	1.01 [0.95, 1.07]
2 Maternal mortality (infant mortality level)	4		Risk Ratio (Random, 95% CI)	0.88 [0.65, 1.20]
2.1 Countries with low infant mortality	1		Risk Ratio (Random, 95% CI)	0.33 [0.01, 9.44]
2.2 Countries with high infant mortality	3		Risk Ratio (Random, 95% CI)	0.89 [0.64, 1.23]
3 Maternal mortality (maternal mortality level)	4	161240	Risk Ratio (M‐H, Fixed, 95% CI)	0.91 [0.76, 1.08]
3.1 Countries with low maternal mortality	1	550	Risk Ratio (M‐H, Fixed, 95% CI)	0.33 [0.01, 8.15]
3.2 Countries with high maternal mortality	3	160690	Risk Ratio (M‐H, Fixed, 95% CI)	0.91 [0.76, 1.08]
4 Perinatal mortality (maternal mortality level)	1	73743	Risk Ratio (M‐H, Fixed, 95% CI)	0.95 [0.88, 1.03]
4.1 Countries with low maternal mortality	0	0	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
4.2 Countries with high maternal mortality	1	73743	Risk Ratio (M‐H, Fixed, 95% CI)	0.95 [0.88, 1.03]
5 Maternal mortality (prevalence of vitamin A deficiency)	4	161240	Risk Ratio (M‐H, Random, 95% CI)	0.87 [0.64, 1.20]
5.1 Low prevalence of vitamin A deficiency	1	550	Risk Ratio (M‐H, Random, 95% CI)	0.33 [0.01, 8.15]
5.2 High prevalence of vitamin A deficiency	3	160690	Risk Ratio (M‐H, Random, 95% CI)	0.88 [0.63, 1.23]
6 Perinatal mortality (prevalence of vitamin A deficiency)	1	76176	Risk Ratio (M‐H, Fixed, 95% CI)	1.01 [0.95, 1.07]
6.1 Low prevalence of vitamin A deficiency	0	0	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
6.2 High prevalence of vitamin A deficiency	1	76176	Risk Ratio (M‐H, Fixed, 95% CI)	1.01 [0.95, 1.07]
7 Maternal mortality (prevalence of HIV in the general population)	4	161240	Risk Ratio (M‐H, Random, 95% CI)	0.87 [0.64, 1.20]
7.1 Countries with low HIV prevalence	4	161240	Risk Ratio (M‐H, Random, 95% CI)	0.87 [0.64, 1.20]
7.2 Countries with high HIV prevalence	0	0	Risk Ratio (M‐H, Random, 95% CI)	0.0 [0.0, 0.0]
8 Perinatal mortality (prevalence of HIV in the general population)	1	76176	Risk Ratio (M‐H, Fixed, 95% CI)	1.01 [0.95, 1.07]
8.1 Countries with low HIV prevalence	1	76176	Risk Ratio (M‐H, Fixed, 95% CI)	1.01 [0.95, 1.07]
8.2 Countries with high HIV prevalence	0	0	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
9 Maternal mortality (dose)	3	160690	Risk Ratio (M‐H, Random, 95% CI)	0.88 [0.63, 1.23]
9.1 Daily 10,000 IU	0	0	Risk Ratio (M‐H, Random, 95% CI)	0.0 [0.0, 0.0]
9.2 Others	3	160690	Risk Ratio (M‐H, Random, 95% CI)	0.88 [0.63, 1.23]
10 Perinatal mortality (dose)	1	76176	Risk Ratio (M‐H, Fixed, 95% CI)	1.01 [0.95, 1.07]
10.1 Daily 10,000 IU	0	0	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
10.2 Others	1	76176	Risk Ratio (M‐H, Fixed, 95% CI)	1.01 [0.95, 1.07]
11 Maternal mortality (regimen)	4	161240	Risk Ratio (M‐H, Random, 95% CI)	0.87 [0.64, 1.20]
11.1 Daily	1	550	Risk Ratio (M‐H, Random, 95% CI)	0.33 [0.01, 8.15]
11.2 Weekly	3	160690	Risk Ratio (M‐H, Random, 95% CI)	0.88 [0.63, 1.23]
11.3 Other regimen	0	0	Risk Ratio (M‐H, Random, 95% CI)	0.0 [0.0, 0.0]
12 Perinatal mortality (regimen)	1	76176	Risk Ratio (M‐H, Fixed, 95% CI)	1.01 [0.95, 1.07]
12.1 Daily	0	0	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
12.2 Weekly	1	76176	Risk Ratio (M‐H, Fixed, 95% CI)	1.01 [0.95, 1.07]
12.3 Other regimen	0	0	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
13 Maternal mortality (duration of intervention)	2	60216	Risk Ratio (M‐H, Fixed, 95% CI)	1.16 [0.82, 1.64]
13.1 One month or less	1	550	Risk Ratio (M‐H, Fixed, 95% CI)	0.33 [0.01, 8.15]
13.2 More than one month	1	59666	Risk Ratio (M‐H, Fixed, 95% CI)	1.18 [0.83, 1.68]
14 Perinatal mortality (duration of intervention)	0	0	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
15 Maternal mortality (trimester of pregnancy)	4	161240	Risk Ratio (M‐H, Random, 95% CI)	0.87 [0.64, 1.20]
15.1 Pre‐pregnancy	2	101024	Risk Ratio (M‐H, Random, 95% CI)	0.77 [0.50, 1.17]
15.2 First trimester	1	59666	Risk Ratio (M‐H, Random, 95% CI)	1.18 [0.83, 1.68]
15.3 Second trimester	0	0	Risk Ratio (M‐H, Random, 95% CI)	0.0 [0.0, 0.0]
15.4 Third trimester	1	550	Risk Ratio (M‐H, Random, 95% CI)	0.33 [0.01, 8.15]
15.5 Mixed	0	0	Risk Ratio (M‐H, Random, 95% CI)	0.0 [0.0, 0.0]
16 Perinatal mortality (trimester of pregnancy)	1	76176	Risk Ratio (M‐H, Fixed, 95% CI)	1.01 [0.95, 1.07]
16.1 Pre‐pregnancy	1	76176	Risk Ratio (M‐H, Fixed, 95% CI)	1.01 [0.95, 1.07]
16.2 First trimester	0	0	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
16.3 Second trimester	0	0	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
16.4 Third trimester	0	0	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
16.5 Mixed	0	0	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]
17 Maternal mortality (randomisation)	3	160690	Risk Ratio (M‐H, Random, 95% CI)	0.88 [0.63, 1.23]
17.1 Cluster‐randomised	3	160690	Risk Ratio (M‐H, Random, 95% CI)	0.88 [0.63, 1.23]
17.2 Individual‐randomised	0	0	Risk Ratio (M‐H, Random, 95% CI)	0.0 [0.0, 0.0]
18 Perinatal mortality (randomisation)	1	76176	Risk Ratio (M‐H, Fixed, 95% CI)	1.01 [0.95, 1.07]
18.1 Cluster‐randomised	1	76176	Risk Ratio (M‐H, Fixed, 95% CI)	1.01 [0.95, 1.07]
18.2 Individual‐randomised	0	0	Risk Ratio (M‐H, Fixed, 95% CI)	0.0 [0.0, 0.0]