The impact of fetal size and length of gestation on 6-sulphatoxymelatonin excretion in adult life

Recent studies have shown that intrauterine growth retardation or fetal dis tress in human infants is associated with a pronounced reduction in melaton in secretion during the first 3 months of life. It is not known whether the se associations persist beyond infancy. We have therefore examined the rela tionship between birthsize and melatonin secretion in 159 men and women age d 10, born in Adelaide, South Australia. Melatonin secretion was estimated by analysing the overnight urinary excretion of 6-sulphatoxymelatonin. The overnight excretion ranged from 1.7 to 128.9 nmoles/subject, was higher in women than in men (46.5 vs 34.1 nmoles, P = 0.003) and was significantly ne gatively correlated with the body mass index (P = 0.006). Excretion correla ted with both birthweight and ponderal index at birth (P = 0.04 and P = 0.0 1 respectively after adjustment for gestational age) and also fell with inc reased duration of gestation (P = 0.007). The effects of adult body mass in dex added to that of low birthweight in predicting 6-sulphatoxymelatonin ex cretion. These data suggest that urinary 6-sulphatoxymelatonin excretion wa s impaired in adults who were growth restricted prenatally or were delivere d after 40 weeks gestation.