questionnaire: average calling time per day based on bills, location of mobile phone when not in use (in handbags, clothing pockets, ≥ 60-70 cm away from the body), use of hands-free equipment, use of phones for other applications (to send messages, to listen to music, and to play games)
calculation: effective SAR calculated as average duration of calling time per day multiplied with SAR reported by the manufacturer
All data pertaining to mobile phone use such as average calling time per day, the location of the mobile phones when not in use, use of phones for other applications, SAR and the average of the calculated effective SAR, except the use of hands-free devices were different between the case group and the control group. A significant association between the calculated effective SAR and the risk of spontaneous abortions was observed (OR 1.11; CI 1.07-1.16). The results suggest that use of mobile phones could be related to the early spontaneous abortions.