Heart rate patterns in fetuses exposed to cocaine.

Heart rate patterns of 42 fetuses exposed to cocaine near the time of delivery were compared with patterns in 42 controls. Decreased long-term variability and an increased frequency of contractions were observed more often in the cocaine group (P = .046 and P = .0306, respectively). There were no significant differences in the frequency of fetal tachycardia or decelerations. Although accelerations were less frequent in cocaine-exposed fetuses, the difference compared with controls was not statistically significant. We found no characteristic heart rate pattern in fetuses exposed to cocaine near delivery. The heart rate patterns likely represent the underlying state of fetal oxygenation. Frequent contractions in an unstimulated labor should raise suspicions of maternal cocaine use.