Breasts appear on the left and right sides are not equal, the size is not the same, in the clinical among the general is due to the following several reasons: a situation may be due to the exercise habits of each person, the size of the breast is generally closely related to the posture of the exercise, the amount of exercise, such as the common right force hand people often use the process more, the right side of the chest muscle is more developed, it feels or from the surface can see relatively The right side of the mammary gland development is a little larger, the left side is relatively small. Another situation may be due to congenital factors, during embryonic development, one side of the mammary gland is abnormally developed, after birth, there will be bilateral mammary glands are not equal, the size of the situation is not the same. It is also common for some breastfeeding women to have asymmetrical size due to breastfeeding, mostly due to the habit of breastfeeding more on one side and less on the other, so after breastfeeding and weaning, the side that often breastfeeds has atrophied and has an unequal size, but this situation does not have any effect on women.