Nowadays, mobile communication technology has become essential; thus, it is important to consider the effect of electromagnetic radiation from mobile terminals such as smartphones on the human body. In this study, we calculated the specific absorption rate (SAR) and temperature increase in pregnant women exposed to a smartphone’s radiation at 13, 18, and 26 weeks of gestation. The results indicate that the SARs were much lower in fetuses than in pregnant women under all of the calculation settings in this study. Moreover, the maximum temperature increases in fetuses were half of those in pregnant women.