Awaiting cervical change for the diagnosis of preterm labor does not compromise the efficacy of ritodrine tocolysis

We retrospectively studied 209 patients treated with ritodrine hydrochloride to determine whether change in cervical effacement or dilatation during a period of observation before therapy would result in decreased efficacy of ritodrine, as measured by delivery delays of 48 hours, 1 week, or until ≥37 weeks' gestation; neonatal intensive care unit admission; and neonatal respiratory distress syndrome. Patients who were ≥3 cm dilated on admission were at high risk of therapy failure by all outcome measures compared with patients <3 cm dilated. For patients <3 cm dilated on admission, there was no difference in outcome when patients treated for contractions only were compared with those treated after change in effacement or dilatation had been documented. We conclude that awaiting change in cervical effacement or dilatation to be more certain of the diagnosis of preterm labor will not compromise the efficacy of ritodrine tocolysis.