CATCH-UP GROWTH: TO BE OR NOT TO BE

Introduction

Growth is a hall mark of children. Any growth deviation is viewed with great concern and remedies undertaken to restore normalcy. Children: born small for gestational age (SGA), Protein Energy Malnutrition-primary or secondary or failure to thrive (FTT) experience inadequate growth and respond with a positive growth with appropriate intervention. This positive growth is regarded as Catch-Up Growth (CUG). Though the pathophysiological considerations put forward in this write-up can apply to the morbidities mentioned above, the focus in this write-up is on SGA.

SGA and CUG

What is SGA and CUG? SGA describes any infant whose birth weight and/and or birth length was less than the 3rd percentile adjusted for prematurity (gestational age), why in simple term, Catch-up Growth has been defined as a height velocity above the statistical limits of normality for age following a transient period of growth inhibition. 1There are other elaborate definitions which considers standard deviations and specifically link it to weight or height/length 2, 3.
Between 3 and 10 % of live births worldwide each year are diagnosed asSGA. The factors why an infant is born SGA can be quite complex. These include fetal, maternal, placental, and/or demographic factors. 85 % of SGA babies will achieve CUG by 2 years and usually by six months4.

Following the thrifty hypothesis proposed by Barker5, dozens of epidemiological studies have confirmed his programing hypothesis 6.

The thrifty phenotype hypothesis states that reduced fetal growth is strongly associated with a number of chronic conditions later in life. This increased susceptibility results from adaptations made by the fetus in an environment limited in its supply of nutrients. On the other hand CUG has similar long term health outcomes as occurs with SGA. The question then is should we promote CUG? 7

This questions cannot be answered directly. There are definite benefits for CUG (especially among those born preterm as well) particularly for sparing brain growth with its attendant benefits for cognition.However if this benefit is weighed against the long term development of metabolic syndrome of insulin insensitivity, coronary heart disease, and obesity etc., the answer to the question posed is still in the air.

It is known that if CUG is achieved gradually without accumulation of abdominal fat in the first two years, the incidence of the associated metabolic syndrome is not significant.

Conclusion.

While it is desirable for CUG to be attained in all children who have experienced negative growth particularly those born SGA, it is important to bear in mind that both SGA and CUG share some common long term deleterious health outcomes. This therefore calls to mind whether CUG should be promoted. Since there is literature evidence to suggest that it is the SGAs that experience accelerated CUG in the first 2 years thereby accumulate abdominal fat, efforts at ensuring growth monitoring while aiming for CUG should be quite useful. The other area of growth monitoring aimed at preventing metabolic syndrome in children is between 2 and 5 years. Children who have excessive store of fat at this ages tend to develop this syndrome. It must also be stated that since the causative factors for SGA are known, efforts should be made to prevent SGA and in so doing reduce the decision dilemma which this communication poses.

Key words: Catch –up Growth, Small for Gestational Age, Protein Energy Malnutrition, Failure to Thrive

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