I have read babies cry more in yellow rooms and tempers fly there as well. I always limit my use of yellow in a baby quilt. Studies have also shown babies like to look at high contrast of colors, which is why you see alot of black and white toys for infants. Black and white may be a boring quilt but you could use other dark to white contrasts. There are no rules though, use what you like or ask the Mother for her color preferences. To keep the quilt safe don't attach anything the baby can pluck out and put in its mouth, like buttons or attached ribbons.