Threatened preterm delivery remains a public health problem because of its human and economic consequences.Tocolysis is a treatment aiming to reduce or stop uterine contractions during the threat of premature delivery. This therapy aims to prolong the pregnancy in order to limit the consequences in terms of mortality and morbidity. It can delay delivery by about 48 hours, rarely by more than 7 days. Before performing tocolysis, it is necessary to eliminate any contraindication to this treatment, to confirm the diagnosis of threat of premature delivery, to evaluate its severity and to specify its origin (ultrasound, biological examinations). The therapeutic strategy to be implemented calls for rest, which is essential, and tocolysis.2 Beta mimetics (salbutamol) show short-term efficacy and a reduction in preterm delivery rates. However, their serious maternal adverse effects, essentially cardiac, pulmonary and metabolic, which can lead to maternal death, and the respect of their contra-indications, precautions for use and drug interactions, as well as the necessity.