Postnatal factors associated with failure to thrive in term infants in the Avon Longitudinal Study of Parents and Children

Objectives: To assess the contribution of postnatal factors to failure to thrive (FTT) in infancy, defined as growth faltering up to 9 months of age. Design: A longitudinal study of term infants, using conditional weight gain and prospectively collected feeding data. Setting: A large cohort study, the Avon Longitudinal Study of Parents and Children (ALSPAC), representative of the British population. Participants: 11,718 infants born at 37-41 weeks gestation without major malformations and with a complete set of weight measurements in infancy (83% of original ALSPAC birth cohort). Demographic and feeding data were prospectively collected by questionnaires completed by the parents. Outcomes: Conditional weight gain was calculated for the periods birth to 8 weeks and 8 weeks to 9 months. Cases of growth faltering were defined as those infants with a conditional weight gain below the 5th centile, and these were compared with the rest of the cohort as the control group. Results: In multivariable analysis, maternal factors predicting poor infant growth were height 32 years. Growth faltering between birth and 8 weeks was associated with infant sucking problems regardless of the type of milk, and with infant illness. After 8 weeks of age, the most significant post-natal influences on growth were the efficiency of feeding, the ability to successfully take solids, and the duration of breastfeeding. Conclusions: The most important post-natal factors associated with growth faltering are the type and efficiency of feeding: no associations were found with markers of social deprivation and neglect. In the first eight weeks of life weak sucking is the most significant symptom for both breast and bottle fed babies. After 8 weeks, the duration of breastfeeding, the quantity of milk taken and difficulties in weaning are the most important influences.