BACKGROUND

Failure to thrive is a term which describes children who fail to grow at the expected rate, with various definitions, including 'infants and young children whose growth is substantially less than that of their peers' (4). One factor which all definitions have in common is that cases are defined by weight gain, so the term weight faltering is preferred as it avoids the prejoritive use of 'failure' . Anthropometric measures are used to identify cases, with the development of conditional standards (5-7) taking into consideration an infant's weight gain compared with the weight gain of other infants of the same sex and initial weight, and regression towards the mean.

Analysis of the epidemiology of growth faltering in the ALSPAC cohort has identified significant correlations with parental height, and found that the condition is more common not in poorer families as traditionally thought, but in larger families (1). The most important postnatal factors associated with growth faltering were found to be the type and efficiency of feeding (2). Further work has confirmed deficits in IQ at 8 years amongst the ALSPAC cohort of infants with weight faltering (3), in keeping with existing and extensive literative on adverse cognitive and developmental outcomes. One may predict that these adverse effects extend to emotional and psychological development, but such outcomes have been less widely investigated and these findings have not been confirmed in the existing, albeit limited literature.

The most relevant UK study followed up 89 cases of children who failed to thrive as infants and 91 controls at 12 years (8). Cases were significantly shorter and lighter at 12 and had significantly lower BMIs, but did not enter puberty any later. They were more likely to rate their appetite as lower than their best friend's, were more satisfied with their body shape and had significantly lower eating behaviour restraint scores. No significant difference existed in any measures of anxiety, depression and self esteem, and the authors concluded that failure to thrive in infancy is not associated with any adverse emotional development in childhood. Indeed, some of the outcomes could even be perceived as positive, such as greater satisfaction with body shape. However, other literature is suggestive of negative psychological sequalae of weight faltering, with Chung et al finding higher psychological distress scores in adults with a lower weight gain up to 7 years old (9), and Barker et al finding that men and women who commit suicide had low rates of weight gain in infancy, taking account of social class and infant feeding (10). A more recent study based in Jamaica reported early childhood stunting was associated with more anxiety, depression and hyperactive behaviour, and lower self-esteem in late adolescence (11). Although this study focussed on a more extreme form of weight faltering due to undernutrition in a developing country, it is feasible that the effect, albeit smaller, could be extrapolated to less severe weight faltering in the developed world. Evidence linking growth faltering with insecure attachment (12-14) also adds support to the hypothesis for adverse effects on later emotional development.

Historically, 'catch up growth' was encouraged in the management of weight faltering. However evidence now suggests that rapid weight gain in infancy is associated with later obesity and subsequent increased risk for cardiovascular disease and diabetes (15-16). Recommendations for the management of weight faltering therefore need re-evaluating, with a view to balancing the risks to the child (17). In order to do this we need a comprehensive picture of the consequences of weight faltering, including the psychological outcomes as well as the growth outcomes.

The conflicting and limited literature on this topic highlights the need for further research. Use of the ALSPAC dataset would address this need, and would comprise the largest group studied with respect to the psychological and emotional consequences of weight faltering.

METHODOLOGY

The project will be undertaken as part of an academic foundation programme and supervised by Professor Alan Emond. No extra funding is required. As existing data only will be used, generic ALSPAC ethical approval will apply.

Data analysis will be conducted using STATA and statistical support will be provided by Colin Steer and Peter Blair

Cases of weight faltering will be defined as the slowest gaining 5% of infants using a weight gain criterion conditional on initial weight from birth to 6-8 weeks, 6-8 weeks to 9 months, and birth to 9 months, as used in the existing studies on weight faltering in the ALSPAC. Cases of 'early' and 'late' weight faltering in infancy will be further stratified according to BMI at 8 years- ie whether growth had caught up or not. Associations between growth faltering and psychological outcomes will be adjusted for family socio-demographic factors, age of onset of puberty, and child's IQ

Statistical methods will include univariate analysis, multivariate modelling and missing data inputation.