Peer-reviewed article

LONG-TERM ASSOCIATION BETWEEN BREASTFEEDING DURATION AND NUTRITIONAL STATUS IN SCHOOL-AGED CHILDREN: A SYSTEMATIC REVIEW

Galuh Indiradini, Rizki Meizikri · 29 Sept 2026

Abstract

Introduction: Breastfeeding is a double-duty action proposed to protect simultaneously against undernutrition and overnutrition, yet the shape of the duration–response relationship between breastfeeding and nutritional status in early childhood remains contested, particularly in settings experiencing the double burden of malnutrition. This review aimed to synthesise primary evidence published in the last five years on the association between breastfeeding duration (≤1, 3–5, 6, 6–11 and ≥12 months) and the full spectrum of nutritional status (stunting, underweight, normal weight, overweight and obesity) in children aged 2–6 years. Methods: The study strictly adhered to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) 2020 guidelines. Randomised controlled trials (RCT), prospective and retrospective cohort, case-control and cross-sectional studies were eligible; systematic reviews and meta-analyses were excluded from the evidence tables but used in the discussion. Risk of bias was appraised with a ROBINS-E-adapted domain tool and the Newcastle–Ottawa Scale (NOS) for observational studies and RoB 2 for randomised evidence. Where estimates were comparable, ratio measures were oriented as longer/any versus shorter/no breastfeeding and pooled using DerSimonian–Laird random-effects models, with subgroup, leave-one-out, cumulative, meta-regression and small-study analyses. Certainty was graded with GRADE. Results: 41 studies from 25 countries met eligibility (40 observational, one secondary analysis of a cluster-RCT), comprising more than 161,000 children in the 37 studies that reported sample size. Twenty-seven studies addressed over-nutrition and 13 under-nutrition. Longer or any breastfeeding was associated with lower odds of overweight/obesity (10 estimates from 9 studies; pooled ratio 0.71, 95% CI 0.63–0.80; I² = 60.8%; 95% prediction interval 0.50–1.01), robust to leave-one-out and trim-and-fill adjustment (0.73, 0.64–0.83). The association was stronger for exclusive breastfeeding (0.61, 0.53–0.71) than any/full breastfeeding (0.76, 0.66–0.86; P-between = 0.036) and for obesity (0.55, 0.43–0.71). All seven continuous estimates showed lower BMI z-scores with longer breastfeeding (−0.02 to −0.50). For stunting, pooling was dominated by extreme heterogeneity (0.49, 0.08–3.17; I² = 98.4%) driven by a national survey showing higher stunting with breastfeeding into the third year; after its exclusion the association was protective and homogeneous (0.27, 0.19–0.38; I² = 0%). Most observational studies had some concerns (65.0%) or high (35.0%) overall risk of bias, principally from confounding and recall-based exposure measurement. Discussion: The evidence is compatible with a protective, approximately monotonic association between longer (particularly exclusive) breastfeeding and overweight/obesity at 2–6 years, with benefit already apparent after 3–5 months and extending beyond 12 months. For linear growth, exclusive breastfeeding to 6 months and continued breastfeeding into the second year are associated with less stunting, whereas the apparent harm of breastfeeding beyond 24 months in food-insecure settings is most plausibly explained by reverse causation and inadequate complementary feeding rather than by breast milk itself. Conclusion: Longer breastfeeding is associated with a more favourable nutritional status in early childhood, particularly lower overweight and obesity, with low-certainty evidence; the association with stunting depends on complementary-feeding context and is of very low certainty. Programmes should protect exclusive breastfeeding for six months and continued breastfeeding with adequate complementary feeding, while future cohorts should use prospectively recorded duration categories and causal designs.