To determine if discriminatory P or E2 concentrations can be established for early diagnosis of EP after IVF, 282 pregnancies were studied 11, 13, 15, and 17 days after ET. Receiver-operator characteristic analysis of P and E2 indicated no clinically useful threshold value for EP. No significant differences in P or E2 was seen when intrauterine and extrauterine pregnancies or viable and nonviable pregnancies were compared. All EPs had P < 50 ng/mL and E2 < 500 pg/mL at 11 days after ET. Serum P and E2 cannot differentiate EPs from intrauterine pregnancies nor viable from nonviable pregnancies resulting from IVF.