[Study on the association between different feeding methods during the first six months after birth and physical growth of children aged 3 to 5 years based on the Taicang and Wuqiang mother-child cohort study in China]

Objective: To explore the association between different feeding methods during the first six months after birth and the physical growth of children aged 3 to 5 years. Methods: Data were from the "Taicang and Wuqiang mother-child cohort study"(TAWS) in China. Children were enrolled at birth between November 2016 and September 2020 and followed up at 1, 2, 3, 6, 8, 12, 18, and 24 months, as well as at ages 3 to 5 years. Based on feeding methods within six months of age, children were categorized into an "exclusive breastfeeding group" and a "formula-feeding group". Birth-related information and feeding practices between 8 and 24 months were collected, alongside dietary habits, physical activity, and illness during preschool years. Height and weight of preschool children were measured to calculate height-for-age Z-score (HAZ), weight-for-age Z-score (WAZ), body mass index-for-age Z-score (BAZ), and the rates of stunting, underweight, wasting, overweight, and obesity. After adjusting for demographic factors, birth-related information, feeding practices between 8 to 24 months, preschool dietary habits, physical activity, and health status, multiple linear regression and logistic regression were adopted to analyze the influence of feeding methods within six months of age on the physical growth of children aged 3 to 5 years. Results: A total of 1 233 children were included, comprising 629 boys and 604 girls. The number of children aged 3, 4, and 5 years was 436, 406, and 391, respectively. About 754 children were categorized into the exclusive breastfeeding group and 479 into the formula-feeding group. Children who were introduced to formula milk within six months of age had higher HAZ (0.09±0.99), WAZ (0.24±1.07) and BAZ (0.26±1.11) scores at ages 3 to 5 compared to the exclusive breastfeeding group [HAZ, WAZ, and BAZ were (-0.04±0.92), (0.06±1.02) and (0.11±1.08), respectively]. After adjusting for confounding factors, multiple linear regression analysis showed that the β (95%CI) values for HAZ, WAZ and BAZ in the formula-feeding group were 0.16 (0.06-0.25), 0.17 (0.06-0.29) and 0.15 (0.02-0.27), respectively, compared to the exclusive breastfeeding group. After adjusting for confounding factors, the results of the multivariate logistic regression model indicated that there were no statistically significant differences in the risks of stunting, underweight, wasting, overweight, and obesity during the preschool years between the exclusive breastfeeding group and the formula-feeding group, with OR (95%CI) values of 1.04 (0.41-2.62), 0.99 (0.27-3.57), 1.63 (0.53-4.95), 1.08 (0.66-1.74), and 1.58 (0.70-3.60), respectively. Conclusion: Exclusive breastfeeding within six months of age does not increase the risk of undernutrition (including stunting, underweight or wasting) during preschool years. However, the introduction of formula feeding within six months of age significantly increases the physical growth level of the preschool stage.