Changes in basal body temperature and the onset of labor

The presence of change in basal body temperature (BBT) before onset of labor was tested by analyzing BBT charts. Wight-two women agreed to participate and were instructed in the proper measurement and recording of oral BBTs during the last five weeks of pregnancy. Comments were recorded daily for any factors affecting BBT existed. The data analysis was done on all valid charts returned, (25 of 28). Eight of the 25 charts showed isolated BBTs that dropped significantly (< 0.5° F) below the baseline, bur no pattern linked those charts. CUSM analysis showed no significant drop in the baseline BBT at any time during the final 21 days before labor. The findings suggest that BBT can not be used as a predictor of onset of labor in humans.