Bulletin of the World Health Organization

Maternal multiple micronutrient supplementation and pregnancy outcomes in developing countries: meta-analysis and meta-regression

Kosuke Kawai, Donna Spiegelman, Anuraj H Shankar & Wafaie W Fawzi

Volume 89, Number 6, June 2011, 402-411B

Table 7. Results of subgroup analysis and meta-regression for the effect of maternal micronutrient supplementation on perinatal mortality in randomized controlled trials conducted in developing countries

Characteristic No. of trials Pooled RR (95% CI) Univariate meta-regression
P-value for test for heterogeneity by covariate Residual I2 after adjusting for covariate (P-value) Reduction in I2 after adjusting for covariate (%)
Average gestational age at initiation of supplements 0.003 0% (0.49) 100
< 20 wk 7 1.28 (1.10–1.49)
≥ 20 wk 4 0.88 (0.80–0.97)
No maternal education 0.009 17% (0.31) 71
< 50% 8 0.93 (0.82–1.06)
≥ 50% 3 1.41 (1.14–1.75)
Iron dose in treatment and control groups 0.19 47% (0.05) 19
Same 5 0.94 (0.79–1.12)
Different 6 1.18 (0.95–1.47)
Maternal underweighta 0.36 55% (0.01) 5
< 20% 8 1.00 (0.84–1.19)
≥ 20% 3 1.22 (0.97–1.54)
Average maternal height 0.90 58% (0.008) 0
< 155 cm 6 1.09 (0.89–1.34)
≥ 155 cm 5 1.00 (0.75–1.33)
Primiparas 0.91 58% (0.008) 0
< 35% 6 1.10 (0.85–1.44)
≥ 35% 5 0.97 (0.83–1.14)
Effect of supplementation on risk of LGA 0.86 56% (0.02) 0
< 10% (RR < 1.10) 4 1.19 (0.92–1.54)
≥ 10% (RR ≥ 1.10) 5 1.06 (0.81–1.38)
Effect of supplementation on birth weight (mean difference) 0.34 58% (0.008) 0
≥ 50 g 5 0.96 (0.76–1.22)
< 50 g 6 1.14 (0.90–1.44)

CI, confidence interval; LGA, large size for gestational age; RR, relative risk.

a Body mass index (weight in kg divided by square of height in metres) < 18.5.