Neonatal effects of nifedipine and ritodrine for preterm labor

Objective: We compared nifedipine and ritodrine for treatment of preterm la bor with respect to neonatal outcome. Methods: We conducted an open randomized multicenter study of neonatal outc ome in 185 women who received either oral nifedipine (n = 95) or intravenou s (IV) ritodrine (n = 90) for treatment of preterm labor. Secondary outcome measures included neonatal mortality and morbidity, especially neonatal in tensive care unit (NICU) admission, respiratory distress syndrome (RDS), an d intracranial bleeding. Results: There were no significant differences in umbilical artery pH value s and Apgar scores between groups. Nifedipine was associated with lower adm ission rates to the NICU (49% versus 66%; odds ratio 0.51, confidence inter val 0.28, 0.93) compared with ritodrine, and lower incidences of RDS (21% v ersus 37%; 0.46, 0.24, 0.89), intracranial bleeding (18% versus 31%; 0.48, 0.24, 0.96), and neonatal jaundice (52% versus 67%; 0.53, 0.29, 0.97). Logi stic regression analysis showed that even after correction for gestational age at birth, newborn risk of RDS, intracranial bleeding, or neonatal jaund ice was significantly lower in the nifedipine group than the ritodrine grou p. Conclusion: Nifedipine for treatment of preterm labor was associated with a lower incidence of neonatal morbidity than ritodrine. That difference appe ared to be partly because of the higher tocolytic efficacy of nifedipine an d partly because of an intrinsic beneficial effect of nifedipine, or the la ck of harmful effects when compared with ritodrine. (C) 2000 by The America n College of Obstetricians and Gynecologists.