Extremely immature neonates are threatened during the first days after delivery by many conditions which are due to incomplete development. - A key role is played during the first days of extrauterine life by the incidence and degree of the respiratory distress syndrome (RDS). Its incidence in neonates born before the completed 32nd week of gestation is very common. Causal treatment of RDS is not known. To overcome it the neonatologist must use in the majority of infants invasive techniques of controlled ventilation which are associated with the risk of further complications such as barotrauma, retinopathy and later the development of bronchopul- monary dysplasia. Attempts to influence intrauterine maturation of the lungs were started in the fifties. As a routine procedure nowadays corticoids are administered antenatally. Their limited effect divert the attention of perinatologists to other substances which could enhance maturation of pulmonary tissue. In human medicine ambroxol was introduced, in animals opiates are tested as well as beta-mimetics, aminophylline. The greatest hopes were aroused by trials with the use of T-hormones. T-hormones have a maturating regulating function in the foetal organism. They have an affinity for pneumocytes and in animal experiments they have a positive effect on surfac- tant formation. Moreover they act synergically when combined with corticoids. Objective of study: a) to evaluate the safety of the method from the aspect of undesirable side-ef- fects of hormone administration to the mother

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