Do Early Infant Feeding Practices and Modifiable Household Behaviors Contribute to Age-Specific Interindividual Variations in Infant Linear Growth? Evidence from a Birth Cohort in Dhaka, Bangladesh.

Background Causes of infant linear growth faltering in low-income settings remain poorly understood. Identifying age-specific risk factors in observational studies might be influenced by statistical model selection. Objectives To estimate associations of selected household factors and infant feeding behaviors within discrete age intervals with interval-specific changes in length-for-age z-scores (LAZs) or attained LAZ, using 5 statistical approaches. Methods Data from a birth cohort in Dhaka, Bangladesh (n = 1157) were analyzed. Multivariable-adjusted associations of infant feeding patterns or household factors with conditional LAZ (cLAZ) were estimated for 5 intervals in infancy. Two alternative approaches were used to estimate differences in interval changes in LAZ, and differences in end-interval attained LAZ and RRs of stunting (LAZ < -2) were estimated. Results LAZ was symmetrically distributed with mean ± SD = -0.95 ± 1.02 at birth and -1.00 ± 1.04 at 12 mo. Compared with exclusively breastfed infants, partial breastfeeding (difference in cLAZ: -0.11; 95% CI: -0.20, -0.02) or no breastfeeding (-0.30; 95% CI: -0.54, -0.07) were associated with slower growth from 0 to 3 mo. However, associations were not sustained beyond 6 mo. Modifiable household factors (smoking, water treatment, soap at handwashing station) were not associated with infant growth, attained size, or stunting. Alternative statistical approaches yielded mostly similar results as conditional growth models. Conclusions The entire infant LAZ distribution was shifted down, indicating that length deficits were mostly caused by ubiquitous or community-level factors. Early-infant feeding practices explained minimal variation in early growth, and associations were not sustained to 12 mo of age. Statistical model choice did not substantially alter the conclusions. Modifications of household hygiene, smoking, or early infant feeding practices would be unlikely to improve infant linear growth in Bangladesh or other settings where growth faltering is widespread.