Fig. 1.

Receiver-operating characteristic curve of postovulatory day (POD) 12 and POD 14 serum hCG-β levels in order to distinguish between biochemical pregnancies and singleton clinical pregnancies in a fresh IVF-ET cycles and b frozen-thawed ET cycles, and either ended as biochemical pregnancies or early pregnancy loss and live birth in c fresh IVF-ET cycles and d frozen-thawed ET cycles. Blue line reflects POD 12 hCG-β levels; green line reflects POD 14 hCG-β levels; violet line reflects increase fold between POD 12 and POD 14 hCG-β levels