Figure 1.

The nomogram to predict the probability blastocyst formation in routine in-vitro fertilization (IVF) cycles. The nomogram can be applied by following procedures: draw a line perpendicular from the corresponding axis of each risk factor until it reaches the top line labeled “Points”; sum up the points for all risk factors and recorded as the total score; and draw a line descending from the axis labeled “Total points” until it intercepts the lower line to determine the probability of blastocyst formation. The optimal threshold point was calculated using receiver operating characteristic (ROC) curve.