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The Effect of Zinc Supplementation during Pregnancy and Youth on Child Growth up to 5 Years: A Systematic Review and Meta‐Analysis
Author(s) -
Pimpin Laura,
Liu Enju,
Shulkin Masha,
Duggan Christopher,
Fawzi Wafaie,
Mozaffarian Dariush
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.671.7
Subject(s) - medicine , pregnancy , cochrane library , meta analysis , randomized controlled trial , anthropometry , placebo , pediatrics , lactation , publication bias , obstetrics , alternative medicine , pathology , biology , genetics
BACKGROUND Zinc supplementation promotes linear growth in children up to age 5 years. However, there has been no recent review of effects of both maternal and child supplementation trials on multiple anthropometric measure. OBJECTIVE To determine the effect of zinc supplementation during pregnancy, lactation and childhood on height (cm), height‐for‐age z‐score (HAZ) and birth weight (kg) up to age 5 years. METHODS We searched PubMed, EMBASE, the Cochrane Library, and Web of Science without restriction on publication year, setting, or language for randomized clinical trials examining effects of zinc supplementation lasting at least 3 months in pregnant or lactating women, or children under 5 on our outcomes of interest. Manuscript inclusions and data extractions were performed independently and in duplicate. Study quality was evaluated by the Cochrane Risk of Bias tool. Pooled weighted mean differences (MDs) were calculated by random and fixed effects meta‐analysis, with heterogeneity assessed by the I 2 statistic and publication bias by Egger's test. RESULTS We identified 66 trials including 16 of pregnancy, 0 of lactation, 50 of child supplementation including 24,498 unique participants. Mean (SD) age at supplementation was 24.4 (4.4) years for pregnant women and 9.6 (3.1) months for children. Mean supplementation duration was 6.5 (2.1) and 7.1 (3.1) months, and average dose was 27.1 (8.7) and 8.9 (SD 5.6) mg/day, in maternal and child supplementation, respectively. Control was most often placebo (59% of studies), followed by iron with or without folate (27%) and other micronutrients (14%). In pooled analyses, child zinc supplementation increased child height by 0.69 cm (N=36 trials; MD=0.69, 95%CI=0.14, 1.25, P=0.02) and HAZ by 0.09 units (N=38 trials; MD=0.09, 95%CI=0.07, 0.12, P=0.001). Maternal supplementation did not significantly increase child height (N=3 trials; MD=0.65 cm, 95%CI=0.25, 0.40; P=0.70),HAZ (N=3; MD=−0.151, 95%CI=−0.31, 0.01;P=0.06), or birth weight (N=14 trials; MD=0.07 kg, 95%CI=−0.16,0.29; P=0.554). Heterogeneity in these analyses was generally high (I 2 : 80 to 100%) and was not explained by differences in population stunting status, zinc dose, control type, duration of supplementation, or rural vs. urban residence (P‐interaction from 0.21 to 0.40). There was a suggestion of a decreasing effect size for studies with a longer follow‐up duration (P=0.09). Quality ratings were moderate to high for most (82%) studies. CONCLUSION Child but not maternal zinc supplementation increases height and HAZ in children up to 5 years; fewer trials during pregnancy may limit power to detect effects. These novel findings inform the design of evidence‐informed zinc supplementation policies to improve linear growth of children and reduce rates of stunting globally. Support or Funding Information Bill & Melinda Gates Foundation