The independent factors of hypothermia included ASA III (OR = 5.3, 95% CI (1.4 - 19.4), p = 0.013), duration of surgery > 2 h (OR = 3.1, 95% CI (1.2 - 8.1), p = 0.023), preoperative body temperature (OR = 0.2, 95% CI (0.1 - 0.4), p < 0.0001), ambient operating room temperature (OR = 0.6, 95% CI (0.4 - 0.9), p < 0.0001) and overweight (OR = 0.3, 95% CI (0.2 - 0.9), p = 0.038).