We are focusing on two areas of developmental endocrinology and metabolism, the dynamics of pubescence and perinatal calcium metabolism. Having shown that urinary gonadotropins reflect monthly cyclic patterns in adult women, we have used the same methods and demonstrated similar patterns before menarche in the earliest stages of puberty. Urine specimens have been collected for 60 consecutive days in pubescent boys and girls and are being analyzed for gonadotropins and sex steroids. Using autoregression analysis techniques, the corresponding monthly cyclic patterns are being investigated for each of these hormones. Hypocalcemia is a common clinical problem in the newborn infant and probably results from the many perturbations caused by birth. Using newly developed instrumentation to measure ionized calcium we are studying its various plasma factors, such as albumin, whose binding characteristics in the fetus and newborn differ from those in the adult. The primate colony is being utilized to study calcium metabolism in the fetus near term including endocrine regulation of calcium and kinetics. Studies will be confirmed and extended in human subjects utilizing stable isotopes of calcium in the perinatal period and in infancy.