The effect of maternal cocaine use on the fetus: changes in antepartum fetal heart rate tracings.

Fetal heart rate tracings of pregnancies complicated by cocaine use were analyzed to evaluate the effects of subacute maternal cocaine use on the fetus. Nonstress tests were performed twice weekly on patients from the perinatal substance abuse clinic with screening of maternal urine samples for cocaine, amphetamines, phencyclidine, and opiates at the time of each examination. Nonstress tests performed when the urine toxicology screen was positive for cocaine alone (positive cocaine nonstress tests) were paired with those from the same patient but performed when the screen was negative (negative cocaine nonstress tests). The nonstress tests were analyzed with the Lyons scoring system, which evaluates the baseline heart rate, the oscillatory amplitude of the baseline, the oscillatory frequency, decelerations, and accelerations. Twenty pairs of nonstress tests from 20 patients were analyzed. The total score was higher on the negative cocaine nonstress test in 70% of the pairs and equal in the remaining 30% (p less than 0.001). Significant differences occurred in the oscillatory amplitude (p less than 0.001), frequency (p = 0.002), and acceleration scores (p = 0.03) but not the fetal heart rate baseline or the deceleration scores. The observed changes may reflect alterations in fetal central nervous system neurotransmitters and fetal state regulation, which may affect the developing central nervous system of cocaine-exposed fetuses and in turn play a role in the developmental and behavioral abnormalities observed in cocaine-exposed infants.