Abstract
BACKGROUND: Child undernutrition remains a major public health concern. Although Ethiopia is committed to achieving the sustainable development goals of ending child hunger, longitudinal evidence on how infant feeding practices influence undernutrition is limited. This study examined the effect of infant feeding practices on stunting and wasting. METHODS: This study used longitudinal data conducted from 2015 to 2021 at Dabat research center, Northwest Ethiopia. All pregnant women during this period were enrolled. After birth, 878 mother-infant dyads were followed until their first birthday with five time points. Infant feeding practices were defined based on the World Health Organization recommendations. Data were analyzed using STATA/MP version 17.0 and WHO Anthro 2005. A generalized estimating equation model was used to examine the effect of infant feeding practices on stunting and wasting over time, respectively. RESULTS: A total of 602 (68.6%) of infants were exclusively breastfed for the first six months, while only 14% received a minimum acceptable diet. On multivariable analyses, after adjusting for background variables, exclusive breastfeeding (aRR = 0.85; 95% CI: 0.79, 0.99), receiving a minimum acceptable diet (aRR = 0.62; 95% CI: 0.51, 0.76), maternal employment (aRR = 1.25; 95% CI: 1.01, 1.56) and poor handwashing after toilet use (aRR = 1.15; 95% CI: 1.02, 1.30) were significantly associated with stunting. Similarly, exclusive breastfeeding (aRR = 0.49; 95% CI: 0.39, 0.61), maternal education (aRR = 0.71; 95% CI: 0.54, 0.94), lack of handwashing after toilet use (aRR = 1.31; 95% CI: 1.05, 1.63), and absence of postnatal care (aRR = 1.65; 95% CI: 1.09, 2.84) were significantly associated with wasting. CONCLUSION: The findings show that breastfeeding practice was almost consistent with the global target; however, only a small proportion of infants received complementary feeding that met the World Health Organization quality standards. Suboptimal feeding practices, maternal characteristics, and inadequate hand hygiene after toilet use were significantly associated with undernutrition. These findings underscore the need for health policymakers to intensify efforts to promote age-appropriate infant feeding practices, expand postnatal care utilization, and strengthen handwashing behaviors through targeted health education. In addition, advancing maternal education and improving employment opportunities through coordinated policies and programs will be essential for achieving sustained reductions in child undernutrition. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13690-026-01850-1.