[Role of natural feeding in providing newborn infants with progesterone].

The role of breast milk in the provision of the newborn with the sex hormone progesterone was studied. The radioimmunoassay was used to estimate the hormone content in the breast milk during lactation (87 samples) and in the blood plasma of 59 newborns. It was found that during the early postnatal period the progesterone level in the newborn's blood was gradually lowered. The newborn are deprived of placental progesterone as a result of the break of the chain "mother-placenta-fetus" after delivery, that leads to the reduction of the blood progesterone level. At the same time, the high level of progesterone with the necessary amount of the hormone in the period of the postnatal adaptation. The progesterone level in the mature breast milk decreases, however, with the growth of the milk amount received by the newborn the daily progesterone level significantly rises.