Comparison 2.
Subgroup analysis for primary outcomes (MMN with iron and folic acid vs iron with or without folic acid))
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 1 Preterm births: mean maternal BMI | 15 | Risk Ratio (Random, 95% CI) | Subtotals only | |
| 1.1 BMI < 20 kg/m2 | 4 | Risk Ratio (Random, 95% CI) | 0.85 [0.80, 0.90] | |
| 1.2 BMI ≥ 20 kg/m2 | 11 | Risk Ratio (Random, 95% CI) | 1.02 [0.97, 1.07] | |
| 2 Preterm births: mean maternal height | 15 | Risk Ratio (Random, 95% CI) | Subtotals only | |
| 2.1 Maternal height < 154.9 cm | 8 | Risk Ratio (Random, 95% CI) | 0.94 [0.84, 1.06] | |
| 2.2 Maternal height ≥ 154.9 cm | 7 | Risk Ratio (Random, 95% CI) | 0.99 [0.93, 1.06] | |
| 3 Preterm births: timing of supplementation | 15 | Risk Ratio (Random, 95% CI) | Subtotals only | |
| 3.1 Supplementation started before 20 weeks | 11 | Risk Ratio (Random, 95% CI) | 0.94 [0.87, 1.01] | |
| 3.2 Supplementation after 20 weeks | 4 | Risk Ratio (Random, 95% CI) | 1.03 [0.96, 1.10] | |
| 4 Preterm births: dose of iron | 15 | Risk Ratio (Random, 95% CI) | Subtotals only | |
| 4.1 MMN with 30 mg iron vs. supplement with 60 mg iron | 6 | Risk Ratio (Random, 95% CI) | 1.05 [0.92, 1.19] | |
| 4.2 MMN with 60 mg iron vs. supplement with 60 mg iron | 4 | Risk Ratio (Random, 95% CI) | 0.95 [0.85, 1.06] | |
| 4.3 MMN with 30 mg iron vs. supplement with 30 mg iron | 5 | Risk Ratio (Random, 95% CI) | 0.93 [0.83, 1.05] | |
| 5 Small‐for‐gestational age: mean maternal BMI | 14 | Risk Ratio (Random, 95% CI) | Subtotals only | |
| 5.1 BMI < 20 kg/m2 | 4 | Risk Ratio (Random, 95% CI) | 1.00 [0.95, 1.05] | |
| 5.2 BMI ≥ 20 kg/m2 | 10 | Risk Ratio (Random, 95% CI) | 0.86 [0.81, 0.92] | |
| 6 Small‐for‐gestational age: dose of iron | 14 | Risk Ratio (Random, 95% CI) | Subtotals only | |
| 6.1 MMN with 30 mg iron vs. supplement with 60 mg iron | 6 | Risk Ratio (Random, 95% CI) | 0.88 [0.79, 0.98] | |
| 6.2 MMN with 60 mg iron vs. supplement with 60 mg iron | 4 | Risk Ratio (Random, 95% CI) | 0.89 [0.72, 1.11] | |
| 6.3 MMN with 30 mg iron vs. supplement with 30 mg iron | 4 | Risk Ratio (Random, 95% CI) | 0.99 [0.97, 1.01] | |
| 7 Small‐for‐gestational age: timing of supplementation | 14 | Risk Ratio (Random, 95% CI) | Subtotals only | |
| 7.1 Supplementation started before 20 weeks | 10 | Risk Ratio (Random, 95% CI) | 0.97 [0.93, 1.02] | |
| 7.2 Supplementation after 20 weeks | 4 | Risk Ratio (Random, 95% CI) | 0.85 [0.75, 0.98] | |
| 8 Small‐for‐gestational age: mean maternal height | 14 | Risk Ratio (Random, 95% CI) | Subtotals only | |
| 8.1 Maternal height < 154.9 cm | 8 | Risk Ratio (Random, 95% CI) | 0.99 [0.97, 1.01] | |
| 8.2 Maternal height ≥ 154.9 cm | 6 | Risk Ratio (Random, 95% CI) | 0.82 [0.76, 0.89] | |
| 9 Perinatal mortality: mean maternal BMI | 13 | Risk Ratio (Random, 95% CI) | Subtotals only | |
| 9.1 BMI < 20 kg/m² | 4 | Risk Ratio (Random, 95% CI) | 1.05 [0.85, 1.29] | |
| 9.2 BMI ≥ 20 kg/m² | 9 | Risk Ratio (Random, 95% CI) | 1.02 [0.87, 1.19] | |
| 10 Perinatal mortality: mean maternal height | 13 | Risk Ratio (Random, 95% CI) | Subtotals only | |
| 10.1 Maternal height < 154.9 cm | 8 | Risk Ratio (Random, 95% CI) | 1.01 [0.89, 1.14] | |
| 10.2 Maternal height ≥ 154.9 cm | 5 | Risk Ratio (Random, 95% CI) | 1.04 [0.81, 1.34] | |
| 11 Perinatal mortality: timing of supplementation | 13 | Risk Ratio (Random, 95% CI) | Subtotals only | |
| 11.1 Supplementation before 20 weeks | 10 | Risk Ratio (Random, 95% CI) | 1.13 [0.96, 1.33] | |
| 11.2 Supplementation after 20 weeks | 3 | Risk Ratio (Random, 95% CI) | 0.88 [0.80, 0.97] | |
| 12 Perinatal mortality: dose of iron | 13 | Risk Ratio (Random, 95% CI) | Subtotals only | |
| 12.1 MMN with 30 mg iron vs. supplement with 60 mg iron | 6 | Risk Ratio (Random, 95% CI) | 1.19 [0.95, 1.48] | |
| 12.2 MMN with 60 mg iron vs. supplement with 60 mg iron | 3 | Risk Ratio (Random, 95% CI) | 1.08 [0.71, 1.63] | |
| 12.3 MMN with 30 mg iron vs. supplement with 30 mg iron | 4 | Risk Ratio (Random, 95% CI) | 0.92 [0.87, 0.99] |