Preterm labor: current tocolytic options for the treatment of preterm labor.

While tocolytic therapy may not be indicated in all cases of spontaneous preterm labor (SPTL), the evidence that they are superior to placebo is robust. The perfect tocolytic that is 100% efficacious and 100% safe does not exist and efforts should continue to develop and introduce safer and more effective agents. A reduction in the rate of neonatal mortality and morbidity using tocolysis has not been shown but no tocolytic study has been powered by numbers sufficient to demonstrate such an effect. Tocolytics can delay delivery long enough to administer a course of antepartum glucocorticoids and arrange in utero transfer to a center with neonatal intensive care facilities, both of which reduce neonatal mortality and morbidity. Few tocolytics (β₂-agonists and atosiban) are licensed for use as tocolytics and only one was developed specifically to treat preterm labor (atosiban). Accordingly, most tocolytics have multi-organ adverse effects. Currently, based on the evidence of safety and efficacy, atosiban should be the first-choice tocolytic for the treatment of SPTL to prevent or delay preterm birth.