Girls’ breasts usually start to develop around the age of 9 to 11, with individual differences.
The development of breasts in girls is usually the first sign of puberty in women, and breast development is mainly caused by estrogen and progesterone hormones released by the ovaries. They can lead to the accumulation of fat in the breasts, which can cause them to enlarge.
The first sign of breast development is a slight swelling underneath the nipple, a stage known as the breast bud. When breasts first begin to develop, they may become soft and sore. A girl’s breasts are fully developed between the ages of 17 and 18, and some children may continue to grow beyond the age of 20.
If a girl experiences any discomfort during breast development or does not develop at a normal age, it is recommended that she should visit a hospital and be treated under a doctor’s supervision.