The Virgin Mary holds her first-born son. He is the second person of the Blessed Trinity and He indicates this with the pose of His hand. He is the first-born from the dead which makes all who follow Him into heaven, His brothers and sisters. Because we are Jesus' siblings, Mary is our mother also. We have been born anew as her spiritual children.
The Bible says that Mary gave birth to her first-born son (Lk 2:7). The Bible was not written to satisfy our curiosity about natural things but to give us theological truth; the chronological disparities in the Bible prove this. There are spiritual teachings hidden in areas we find hard to understand. Using the title first-born in reference to Jesus emphasizes His earthly rights and dignity, points to His eternal rights and glory; but it also implies that we are Mary's other children.
In this painting, I chose white and yellow for Mary's clothing because they are the Vatican colors; Mary, the Ever-Virgin Mother is the Mother of the Church.