As a girl grows into a woman, she'll usually experience a development in the size and shape of her breasts. For each girl, this will happen at a different time, and the majority of the growth will usually be initiated, so to speak, by her very first period. Since it is relatively obvious when the breast begin to grow, especially for the girl herself, there would logically be a point when development will cease. So, when does this happen?
The age at which breasts stop growing is all dependent on the individual. Generally, girls will start growing breasts anywhere between the ages of 7 and 13. When growth begins is determined on your own body and when the level of female hormones escalates to the needed amount. Girls will typically find that their breasts will stop growing around the ages of 17 or 18, though some experts believe that a woman's breasts will reach their final size once they've had a child. But since not all women decide to have children, the average age that a woman will experience a stop in growth is in her late teens.
Starting from the very first spurt in growth to the end of puberty, a girl will go through a total of five stages, for lack of a better word, in the growth of her breasts. The first is basically where she starts as a child prior to puberty. This is then followed by the "bud" stage where nipples distend, and the area will become somewhat tender to the touch and sometimes even painful. The third stage is usually accompanied by her first period, and she'll see the most growth in her breast tissue. The fourth stage will generally usher in the shape and contour of her breasts, and she'll rarely see an increase in size, though some girls will experience minor growth. The final stage is when the breasts cease to enlarge, which is usually right around her 17th or 18th birthday.
Usually, a girl can figure out when her breasts will stop growing based on the size of her female relatives, as heredity plays a role in a woman's breast size. However, this doesn't mean that a girl will end up having the same breast size as her mother, since her father's genetics will also play a part in determining the growth. Just look at pictures to see what the predominant size of the women's breasts are in your family to get a general idea of the most likely size of a girl's breasts.
As mentioned before, many experts believe that a woman's breasts are never completely grown until they've given birth. It is during this time in life when you'll encounter any other growth (other than weight gain). Obviously, the growth is due to the production of milk, and after breastfeeding is complete, a woman may find that her breasts are smaller or larger than they were before. This is another time when genetics come into play in the size and shape of a woman's breasts.
Generally, a girl will experience growth of her breast tissue for approximately four years from the time of her very first period. And since no two people are alike, each girl will have her first period at a different age. This event is by and large a good gauge of when a girl's breasts will truly start and stop growing.