The central rationale of tocolysis for preterm labor (PTL) is to delay delivery for at least 48 h to allow for transfer of the mother to a tertiary facility and for corticosteroids to induce surfactant production in fetal lungs. Beta-mimetics decrease the number of women in preterm labor giving birth within 48 h without reducing adverse neonatal outcomes. Calcium channel blockers inclusive of nifedipine decrease the adverse neonatal outcomes by significantly delaying delivery. Atosiban has the best maternal and fetal safety profile but does not seem to reduce neonatal complications. Magnesium sulfate is controversial as a tocolytic, but is valuable as a neuroprotective agent and for treatment of eclamptic seizures. Indomethacin may be a reasonable first choice for acute tocolytsis in gestational ages less than 32 weeks' gestation. Prolonged use (>48 h) should be avoided. Transdermal nitroglycerin can reduce neonatal morbidity and mortality as a result of decreased risk of birth before 28 weeks' gestation. Nifedipine may be a reasonable first choice because it is easy to administer and also of limited side effects relative to β2-mimetics. Tocolysis does not appear to significantly lengthen the gestational age beyond seven days.
Keywords: Atosiban; beta-mimetic; calcium channel blockers; indomethacin; magnesium sulfate; nitroglycerine; preterm delivery; tocolytics.