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.