Magnetoencephalographic Parameters of Fetal Brain Maturation (P3.338)

OBJECTIVE: To identify quantitative Magnetoencephalographic (MEG) indices of spontaneous brain activity for fetal neurological maturation in normal pregnancies, and examine the effect of fetal state on these indices. BACKGROUND: The fetal brain remains practically inaccessible to functional evaluation in utero. MEG, being non invasive and not dependent on intervening tissue impedances, may be uniquely suited to fill this gap by recording the magnetic fields generated in the fetal brain. Fetal MEG studies have been reported to show signals similar to delta brushes, sharp transients and the discontinuous patterns described in neonatal EEG. DESIGN/METHODS: MEG was performed using a 151 sensors system arranged in a concave array to accommodate the gravid maternal abdomen. Spontaneous MEG brain activity was examined in 22 low-risk fetal recordings with gestational age (GA) ranging from 30-37 weeks. Portions of the MEG data showing a “discontinuous pattern” were selected. Subsequently, Burst duration (BD) and interburst interval (IBI) were calculated and studied in correlation with GA and fetal behavioral state (active or quiet sleep). RESULTS: IBI showed a decrease with gestational age (-0.21 sec/week, P= 0.0031). The mean IBI at 30 weeks GA was 7.04±0.38 seconds, and decreased to 5.55±0.21 seconds at the 37th week of gestation. This trend was only maintained in the quiet-sleep state. With respect to BD, no significant trends were detected with GA and state. CONCLUSIONS: IBI can be quantified as a fetal brain maturational parameter using MEG. The decrease in IBI over the course of a normal pregnancy was similar to the trend reported in the preterm neonatal EEG studies. Quiet sleep could be the optimal state to study such fetal MEG maturational indices. Disclosure: Dr. Haddad has nothing to disclose. Dr. Eswaran has nothing to disclose. Dr. Siegel has nothing to disclose. Dr. Lowery has nothing to disclose. Dr. Govindan has nothing to disclose. Dr. Vairavan has nothing to disclose.