Fig. 2. The typical electroencephalographic wave forms at 2.0, 1.5, 1.0, and 0.5% sevoflurane concentration in the pregnant (A ) and nonpregnant (B ) groups. The reduction in sevoflurane concentration from 2.0 to 0.5% changes electroencephalograms from a high-amplitude slow wave to a low-amplitude fast wave. BIS bispectral index; SEF95 = 95% spectral edge frequency.