The effects of in utero cocaine-exposure on the heart rate and heart rate variability of near and full term infants following orthostatic stress

To understand the effects of in utero cocaine exposure on the developing fetus, we studied the heart rate and the heart rate variability in near and full term cocaine-exposed infants in quiet sleep supine and following orthostatic stress. We studied 21 cocaine-exposed and 23 control infants within 120 hours of birth. Two 30-minute segments of the electrocardiogram (ECG) were recorded and analyzed in the time and frequency domain; the first with the supine infant, horizontal followed by the infant in a 25° head-up tilt. The cocaine-exposed group, as compared with the control group, had a trend toward an increase in heart rate in the horizontal position and a significant increase in heart rate following the tilt in the cocaine-exposed group. The frequency components of the heart rate were lower in the horizontal position and increased following the orthostatic stress. These results are consistent with the known pharmacological actions of cocaine and demonstrate the dangers of cocaine abuse during pregnancy.