Pituitary-gonadal relations in infancy. I. Patterns of serum gonadotropin concentrations from birth to four years of age in man and chimpanzee.

Mixed cord sera (27 male, 28 female) and sera from 105 male and 93 female children aged 5 days to 4 yr were assayed for FSH, LH and hCG. Cord hCG was similar in both sexes (median 58 mIU/ml; range 20-9000), and fell to less than 5 mIU/ml by 5 days of life, a value which is below the limit of detectable cross reactivity in the LH radioimmunoassay. Cord FSH was less than 5.5 mug LER-907/100 ml in both sexes. In boys there was a rapid rise of FSH in early postnatal life, with peak levels up to 55 mug/100 ml between 1 week and 3 months, followed by a decline by 4 months reaching the low values seen in older prepubertal subjects. This postnatal FSH rise was both more marked in females with peak values at 2-3 months up to 169 mug/100 ml, and also more sustained with levels staying above those of older prepubertal children until 4 yr of age. Serum LH levels in the boys were in the adolescent range by 1 week of age, peaked at 1 month and then declined to the usual childhood range by 4 months. A similar pattern, though with lower peak LH values, was seen in the female infants. A longitudinal study of serum FSH and LH values in one male and one female chimpanzee from 17 to 456 days of age showed patterns in serum gonadotropins which paralleled those seen in the human cross-sectional study.