The Mexican bola or pregnancy chime is a pretty and original necklace for pregnant women. Inside the bola, a tiny sort of xylophone is welded, on which a little ball 'dances' around. From approximately twenty weeks into pregnancy, a baby can hear and recognise sounds in the womb. By wearing the ball regularly, low on the belly, the baby will grow familiar with the chiming sound of the bell. The baby will experience the special sound as soothing, both before and after birth.