Changes in fetal hemodynamics with terbutaline treatment and premature labor

The aim of this study was to examine the fetal hemodynamic effects of terbutaline treatment and premature labor. Image-directed pulsed and continuous wave Doppler ultrasound studies, using 3.3-MHz and 5-MHz transducers (GE PASII and ATL echocardiographic machines), were used to assess fetal cardiac blood velocities in three groups of pregnancies matched for menstrual age (MA). Group 1: 13 normal pregnancies, mean MA 31 weeks. Group 2: 7 women in premature labor prior to tocolytic therapy, mean MA 32 weeks. Group 3: 8 women treated with terbutaline, average dose 18.8 mg daily, for previous premature labor, mean MA 31 weeks. Heart rate averaged 150 bpm, 135 bpm, and 127 bpm in the terbutaline, premature labor, and normal groups, respectively, and each were significantly different from each other. Products of time velocity interval and heart rate at the aortic valves were 1603 cm +/- 140 cm, 1413 cm +/- 190 cm and 1238 cm +/- 200 cm, and at the mitral valves 1102 cm +/- 170 cm, 812 cm +/- 110 cm, and 878 cm +/- 150 cm in the terbutaline, premature labor, and the normal groups, respectively. Aortic and mitral blood velocity products of time velocity integrals and heart rates were significantly higher (p = 0.01) in the terbutaline group relative to the normal group. In addition, the terbutaline group was significantly higher than the labor group at the mitral valve (p = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)