Determinants of Infant Growth in a Birth Cohort in the Nepal Plains

This study aimed to identify the determinants of infant growth in terms of length-for-age z-score (LAZ) in a birth cohort (n = 602) in the plains of Nepal. Children were enrolled within 72 h of birth and followed-up every 28 days until they were 2 years. We fitted mixed-effects linear regression models controlling for multiple measurements within individuals to examine the impact of household and maternal factors, feeding practices and infection on infant LAZ. We conducted separate analyses for the age periods 0-6 months (exclusive breastfeeding period) and 7-24 months (complementary feeding period) to check whether the importance of determinants differed by child age. Maternal factors related to both the environment in-utero and in postnatal life were the most important determinants of infant growth. The overall most important determinant of growth was low birthweight. At birth, babies born with low birthweight had a -1.21 (-1.38, -1.05) lower LAZ compared to normal birthweight babies. The difference in LAZ between low birthweight and normal birthweight babies attenuated with age but low birthweight remained the factor with the largest effect size. The second largest factor was maternal education. Infants of mothers with any level of education had a 0.22 (0.07, 0.38) higher LAZ in the 7-24 months age-period than those whose mothers had never been to school. Other relevant determinants were adolescent pregnancy, minimum dietary diversity, symptoms of respiratory infection, household food insecurity, season and maternal absence. The importance of maternal factors for infant growth calls for public health interventions targeting girls and young women.