[Sex differences in the secretion of gonadotropins and sex hormones in newborns and infants].

In normal infants of both sexes pituitary gonadotropin secretion is higher during the first months of life than in the later prepubertal period. In addition, during infancy considerable sex differences can be observed in the secretion pattern of both gonadotropins. Plasma concentrations of LH are higher in boys than in girls until 6 months after birth, while plasma FSH is higher in girls than in boys during the first 2 years of life. The infants' gonads are stimulated by the increased endogenous gonadotropins and respond with elevated sex hormone production. Thus, a testosterone surge with peak values in the normal range of male adults occurs in healthy male infants during the first 6 months and elevated estradiol concentrations comparable to levels seen during advanced puberty can be observed in healthy female infants during the first 2 years of life.