Effects of Nifedipine Therapy for Preterm Labor on Placental and Fetal Doppler Parameters in the First 24 Hours

Objective: To assess the effects of nifedipine administration for 24 hours on placental and fetal cerebral blood flow as well as on fetal cardiac function. Subjects and Methods: This prospective observational study involved 30 pregnant women with a single fetus of 30- 34 weeks’ gestation undergoing tocolysis with nifedipine. We assessed pulsatility index (PI) of the umbilical artery, middle cerebral arteries (MCA) and ductus venosus (DV) twice, immediately before initial nifedipine dose and after 24 hours of therapy. Results: The mean age was 30.1±4.6 years. The pretreat-ment gestational age was 32.6±2.2 weeks. Hemodynamic studies proved non-significant change of maternal blood pressure and fetal heart rate and clinically insignificant drop of maternal heart rate. Treatment resulted in statistically non-significant change of PI of the umbilical artery and statistically significant decrease of PI of the MCA and ductus venosus. However, the decrease was within clinically acceptable levels. Conclusion: Nifedipine tocolytic therapy is safe on maternal cardiovascular system and fetal circulatory status up to 24 hours after starting therapy.