Quantification of fetal magnetoencephalographic activity in low-risk fetuses using burst duration and interburst interval

•Examined fetal neurological maturation indices in normal pregnancies using magnetoencephalographic recordings.•Interburst interval (IBI) decreases with gestational age – a trend similar to EEG findings in premature neonates.•Tracking IBI in quiet sleep state could provide valuable insight into fetal neurological maturation.

ObjectiveTo identify quantitative MEG indices of spontaneous brain activity for fetal neurological maturation in normal pregnancies and examine the effect of fetal state on these indices.MethodsSpontaneous MEG brain activity was examined in 22 low-risk fetal recordings with gestational age (GA) ranging from 30 to 37 weeks. As major quantitative characteristics of spontaneous activity, burst duration (BD) and interburst interval (IBI) were studied in correlation with GA and fetal state.ResultsIBI showed a decrease with gestational age (−0.21 s/week, P = 0.0031). This trend was only maintained in the quiet-sleep state. With respect to BD, no significant trends were detected with GA and state.ConclusionIBI can be quantified as a fetal brain maturational parameter. The decrease in IBI over gestation was similar to the trend reported in the preterm neonatal EEG studies. Quiet sleep could be the optimal state to study such MEG maturational indices.SignificanceWith further investigation, indices extracted from spontaneous fetal brain activity may serve as an early warning for fetal neurological distress.