What is breast ironing, harmful cultural practice affecting 3.8 million women in Africa?

Breast ironing is the process whereby young pubescent girls' breasts are ironed, massaged and/or pounded down through use of hard/heated objects in order for breasts to disappear or delay their development. It's believed that this act protects young girls from harassment, rape, abduction and early forced marriage. The harmful cultural practice affects about 3.8 million women in Africa.