If you were to survey 100 women, asking whether or not their breasts were symmetrical, more than half of them would respond with a resounding “No!” Most women have one breast that is bigger than the other, one breast that hangs lower than the other, or one that has a slightly different shape than the other. Uneven breasts are extremely common, especially during and after breastfeeding. Have you ever wondered what causes breast asymmetry?
Before we explore how breasts can become uneven, we must acknowledge the breast’s anatomy. The structure of the female breast is very complex—it is made up of connective tissue and fat, as well as ducts, lobules, and lobes. Each breast has several lobules that branch out from the nipple. These lobules are connected by a network of ducts. If you are breastfeeding, these ducts carry milk to the areola. From the areola, the ducts link to larger ducts at the nipple.
Between the lobules and ducts are fat, connective tissue, and ligaments. The size of your breasts is largely determined by the amount of fat they contain. The breast itself contains no muscle tissue. However, there is muscle tissue underneath the breasts, separating them from the ribs.
What Causes Breast Asymmetry?
For some women, breast asymmetry begins during puberty. An influx of hormones can cause one breast to start growing before the other, even if they stop growing at the same time. For other women, uneven breasts are simply anatomic variations. These normal growth variations occur for the same reasons we have may have uneven eyebrows or one arm that is slightly shorter than the other.
Having asymmetrical breasts does not immediately put you at a higher cancer risk. Still, if you have uneven breasts or twin breasts – or if you feel a sudden change in shape or size of one or both of your breasts – you should speak with a specialist. A sudden and noticeable difference may be due to the existence of a lump or cyst. Performing regular self-exams and paying close attention to differences within your breasts are extremely important in maintaining breast health.