Foetal growth and increased urinary excretion of 5-oxoproline in Trinidadian infants

ABSTRACT

Size at birth is related to the risk of heart disease, hypertension and diabetes mellitus in later life. Glycine is a conditionally essential amino acid during the perinatal period. The urinary execretion of 5-1-oxoproline has been used as a marker for glycine sufficiency. In Jamaican infants, excretion increased progressively during the first weeks of life and by 6 weeks of age was two-to-three times that seen in infants in the UK. We measured the rate of excretion in 42 infants aged 4-to-6 weeks, delivered at Mount Hope Maternity Hospital (Indian, 17; African, 15; mixed, 10), compared with 22 Caucasian infants born in Southampton. There were no differences between the groups in maternal age, maternal haemoglobin, or parity. Trinidadian infants were statistically significantly lighter, with smaller head circumference than the infants in UK. The differences in weight were more marked for the Indian and mixed infants than for the African infants, although head circumference in the three groups was similar. There was a highly statistically significant increase in the excretion of 5-oxoproline in all groups of Trinidadian infants, compared with UK infants. Maternal haemoglobin related to newborn size. When maternal haemoglobin was controlled, there was a statistically significant inverse relationship between 5-oxoproline excretion and birthweight (r=-0.32, p=0.02) and head circumference (r=-0.27, p=0.05). Infants in Trinidad had levels of urinary 5-oxoproline similar to those found previously in Jamaica and about twice those seen in infants in the UK. These differences do not appear to be accounted for by infant feeding patterns, but may be directly related to aspects of maternal nutrition, and the shape and size of the infant at birth. The data suggest that the availability of glycine might be limiting for foetal growth in the Caribbean, and this could have important implications for the development of diabetes mellitus, hypertension and heart disease in later life (AU)