Question: is eeg safe during pregnancy?
Answer: EEG and MEG are known to be completely safe and non-invasive in general, so this would also apply to pregnant women and fetuses (in fact, off the top of my head I can think of at least 3 fetal MEG studies; see http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2830651/ for a review of the method in general).