Determinants of Underweight Among Children Under Five Years in The Sunyani Municipality, Ghana

Background Underweight refers to a condition where a child’s weight-for-age is below minus two standard deviations (< -2 SD) from the median of the world Health Organisation Child Growth Standards. Underweight in Ghana is impacted by a mix of social, maternal, and environmental factors. Despite the existence of policies such as the National Nutrition Policy (2016–2025) and community-based programmes like the Ghana School Feeding Programme, undernutrition remains. The study therefore assessed the important factors related to underweight among children under five years in the Sunyani Teaching Hospital. Methods This research utilized a descriptive cross-sectional design and a quantitative data collection method to fulfil its intended objectives. The targeted population for the study were all children under five years of age who attended the Child Welfare Clinic at the Sunyani Teaching Hospital during the study period, as well as their mothers or primary caregivers. A systematic random sampling technique was employed to select participants from the hospital’s child welfare attendance register. After computation, 293 participants made up the total sample for the study. Results The mean (SD) children in months were 30.30(± 17.19), height 81.22(± 18.97) and weight 11.32 (± 5.23) with females constituting the majority (65.53%). The prevalence of underweight was found to be 15.4% with the majority (84.6%) classified as having a normal weight. Significant associations were observed with maternal education (χ² = 36.248, p = 0.012), maternal nutritional status (χ² = 18.245, p = 0.003), knowledge of child feeding habits (χ² = 21.783, p = 0.013), and exclusive breastfeeding (χ² = 18.254, p = 0.025). Source of drinking water (χ² = 24.445, p = 0.015), waste disposal practices (χ² = 14.413, p = 0.033), handwashing (χ² = 9.115, p = 0.045), soap availability (χ² = 8.502, p = 0.048), recent illness (χ² = 16.321, p = 0.004), deworming (χ² = 10.121, p = 0.036), immunization (χ² = 12.352, p = 0.024), and meal frequency (χ² = 15.762, p = 0.031). Conclusion This study explored the factors linked to underweight children under five years old, focusing on maternal, environmental, and health-related determinants. It identified underweight as a significant public health issue influenced by a complex interaction of various factors. Key maternal characteristics, including education level, nutritional status, knowledge of child feeding, and exclusive breastfeeding practices, were strongly associated with child nutrition.