The efficacy of UPA did not decrease significantly (P = 0.44) over time, with pregnancy rates at intervals between >48 and 72 hours at 2.3% (95% CI, 1.4%-3.8%), >72 and 96 hours at 2.1% (95% CI, 1.0%-4.1%), and >96 and 120 hours at 1.3% (95% CI, 0.1%-4.8%).