“…The results of previous epidemiological studies suggest a possible relationship between IF and adverse pregnancy outcomes [Lindbohm et al, 1992;Juutilainen et al, 1993]. Previous results from laboratory animal studies suggest that IF disturbed the development of animal embryos [Berman et al, 1990;Farrell et al, 1997;Youbicier-Simo et al, 1997]; however, the results have been inconsistent [Juutilainen, 1991;Chernoff et al, 1992;Brent et al, 1993;Huuskonen et al, 1998a] and most studies conducted in mammals reported no or only slight effects on fetus [Tribukait et al, 1987;Stuchly et al, the fetal development of pregnant mice, regardless of gestational age. Consequently, for our current study, we increased the peak intensity of 20 kHz EMF to 30 mT, which is the limit standard for occupational population at 20 kHz in Korea [Yoo, 2002;Kim et al, 2004].…”