Fetal Rest-Activity Cycles and Chronic Exposure to Antiepileptic Drugs

Abstract

Rest-activity patterns were studied in fetuses exposed to antiepileptic drugs (AEDs) and in control fetuses at three intervals during pregnancy: 20, 32, and 38 weeks. At 20 weeks, periods of rest and activity were distinguished on the basis of fetal motility. Trunk, head, and arm movements were totaled. Periods of absence of movements for greater than 3 min were found in 20 of 31 recordings from AED-exposed fetuses compared with 11 of 20 recordings from controls (p greater than 0.05). The duration of these periods of inactivity did not differ significantly between the two groups. At 32 and 38 weeks, information on fetal motility and fetal heart rate (FHR) were combined to recognize rest-activity patterns according to the fetal behavioral state concept. At 32 weeks, three true fetal behavioral states were found for the study group, while there were none in the control group. Coincidence 1F through 4F occurred significantly less frequently at 32 weeks than at 38 weeks, regardless of whether fetuses were AED-exposed or not: 59% vs. 82% for the study group and 59% vs. 80% for the controls. At 38 weeks, true fetal behavioral states appeared in 20 of 34 fetuses exposed to AEDs and in 17 of 35 controls (p greater than 0.05). The sequence in which parameters changed within state transitions was found to follow the same preferred pattern in both groups. For transitions from behavioral state 1F (quiet sleep) into 2F (active sleep) the FHR pattern changed significantly earlier than fetal body or eye movements, while for the reverse transitions the FHR pattern changed significantly later (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)