[Tocolysis: which are the benefits?].

Spontaneous preterm labor is still a major problem in perinatal medicine and it is associated to overwhelming risks of neonatal morbidity and mortality. Delaying delivery for hours, days or sometimes weeks may greatly reduce the short- and long-term perinatal morbidity improving fetal maturity of several organs and systems. Inhibition of uterine contractions may in fact allow to take advantage of the prenatal administration of glucocorticosteroids, which have been shown to reduce the incidence and severity of newborn respiratory distress syndrome. Moreover, delaying delivery may allow the transfer in utero to a maternity attached to a neonatal intensive care unit, therefore guaranteeing the best care for the preterm newborn. Every day gained between 22 and 28 weeks gestation increases survival by 3%. However, since most of preterm deliveries happened to be after 29 weeks, newborn survival is a secondary issue while the main aim of delaying labor in these cases is to improve the function of fetal systems and to try to understand if it is the case of prolonging pregnancy balancing risks of a hostile intrauterine environment towards the possible complications of a premature extrauterine life.