Fetal cardiac function in response to long-term maternal terbutalin treatment

To evaluate whether long-term human fetal exposure to beta 2-adrenergic receptor agonists elicit alterations in the human fetal heart, a fetal echocardiographic examination was performed in 9 fetuses between the 24th and 35th week of gestation (median 28 weeks) and 9 age-matched controls. Examinations were performed during long-term tocolytic terbutalin treatment. Drug dosages varied between 7.5 and 20.0 mg/day (median 10.0 mg/day) and treatment durations prior to examination varied between 14 and 60 days (median 25 days). No significant differences were noted between the exposed fetuses and their controls as regards FHR, left ventricular dimensions, interventricular septal thickness, left ventricular contractility (fractional shortening) and the derived left ventricular stroke volume. Despite the limited number of subjects it is believed that long-term terbutalin exposure does not have any untoward major fetal left ventricular consequences.