(Breast) Size Doesn't MatterMyth #2: Women with small breasts produce less milk.
Fact: Breast size depends more on the amount of fatty tissue in the breast than the number of milk glands, and no direct link exists between pre-pregnancy breast size and daily milk production. Because breast size is related to the storage capacity of the breasts, women with smaller breasts may need to nurse or pump more often than large-busted women.
The breasts undergo remarkable development of the milk glands and ducts in pregnancy under the influence of estrogen and progesterone, with each breast nearly doubling in weight. The breasts enlarge still further when a mother's milk comes in, usually on the third postpartum day. Thus, most women with smaller breasts prior to pregnancy find their breasts have enlarged considerably by the time milk production begins. If breasts are still small at this point, it can be a cause for concern, and should be discussed with your health care practitioner.
Some breast variations can complicate nursing. Inverted nipples can make it more difficult for an infant to latch on properly, and may require extra instruction from a lactation consultant or certain breastfeeding techniques. (For example, using a breast pump before nursing can often make inverted nipples temporarily protrude.)
While nearly half of all women have a visible degree of breast asymmetry, a marked difference in breast size can be a warning sign of insufficient milk, especially when the smaller breast does not enlarge much in pregnancy or when the milk comes in. Cosmetic and diagnostic breast surgery, particularly procedures that involve a surgical incision at the margin of the areola -- can also put moms at an increased risk for an insufficient milk supply as these incisions may sever the milk ducts.
Every woman should have a prenatal breast exam by her obstetrical care practitioner, both to detect and diagnose breast lumps, as well as to screen for variations that may adversely affect breastfeeding. If risk factors are identified, your doctor can refer you to a lactation consultant for assistance. Fortunately, lactation is a very robust process, and most women are capable of producing more than enough milk to nourish their babies.