The figure on the left is a midwife. In the background an angel announces the birth of Christ to the shepherds.
This was the central predella panel of an altarpiece by the Master of the Castello Nativity in Prato (Museo del Duomo). Two other predella panels of the altarpiece have been identified (Philadelphia, Johnson Collection). The altarpiece came from the church of SS Giusto e Clemente at Faltugnano
