Animal-source foods (ASFs) are a food group of interest for interventions aimed at reducing stunting and other inadequate growth measures in early childhood. The aim of this systematic review was to examine the relation between ASF consumption and stunting in children aged 6–60 mo in low- and middle-income countries (LMICs). The secondary aim was to examine the relation between ASF consumption and other indicators of growth and development (length/height, weight, head circumference, and anemia). A search of the peer-reviewed and grey literature published from January 1980 to June 2017 was conducted. Databases searched included CINAHL, Embase, Global Index Medicus, PubMed, and Web of Science. There were 14,783 records and 116 full text articles dual screened; 21 studies were included in the review and were dual evaluated for risk of bias (RoB). The relation between ASF and stunting (length- or height-for-age z-score←2) was examined in randomized-controlled trials [(RCTs), n = 3] and cross-sectional studies (n = 4) only; ASF reduced stunting in 1 RCT and was associated with reduced stunting in 1 cross-sectional study. We did not identify any longitudinal cohorts that examined this relation. The relation between ASF and secondary indicators length/height, weight, head circumference, and anemia were largely nonsignificant across study designs. The intervention/exposure, comparator, outcome measures, methods, and analyses were highly heterogeneous. Although we did not find a consistent relation between ASF consumption and our primary and secondary outcomes, this may have been a function of inconsistencies in study design. Foods in the whole diet, particularly combination dishes, are inherently difficult to assess. To quantitatively assess the relation between ASF and stunting and other indicators of growth and iron status in early childhood, future research should provide consistency in the definition and quantification of the exposure and outcomes allowing for interstudy quantitative comparisons.

BackgroundDespite considerable global efforts to reduce growth faltering in early childhood, rates of stunting remain high in many regions of the world. Current interventions primarily target nutrition-specific risk factors, but these have proven insufficient. The objective of this study was to synthesize the evidence on the relationship between active tobacco use during pregnancy and growth outcomes in children under five years of age.MethodsIn this systematic review and meta-analysis, six online databases were searched to identify studies published from January 1, 1980, through October 31, 2016, examining the association between active tobacco use during pregnancy and small-for-gestational age (SGA), length/height, and/or head circumference. Ecological studies were not included. A meta-analysis was conducted, and subgroup analyses were carried out to explore the effect of tobacco dosage.ResultsAmong 13,189 studies identified, 210 were eligible for inclusion in the systematic review, and 124 in the meta-analysis. Active tobacco use during pregnancy was associated with significantly higher rates of SGA (pooled adjusted odds ratio [AORs] = 1.95; 95% confidence interval [CI]: 1.76, 2.16), shorter length (pooled weighted mean difference [WMD] = 0.43; 95% CI: 0.41, 0.44), and smaller head circumference (pooled WMD = 0.27; 95% CI: 0.25, 0.29) at birth. In addition, a dose-response effect was evident for all growth outcomes.ConclusionTobacco use during pregnancy may represent a major preventable cause of impaired child growth and development.Electronic supplementary materialThe online version of this article (10.1186/s12889-018-6137-7) contains supplementary material, which is available to authorized users.

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