Having one breast that produces significantly more milk than the other is a common experience for breastfeeding parents. This difference in output, known as supply asymmetry, is normal and rarely indicates a problem with overall milk production. The body’s milk-making tissue is not perfectly symmetrical, but solutions exist. While asymmetry can sometimes lead to discomfort or feeding challenges, it is a manageable situation that can often be resolved with simple, targeted adjustments.
Understanding Why Supply Imbalance Occurs
The primary reason for a difference in milk production relates to anatomical variations between the two breasts. Just as one hand is dominant, one breast may naturally contain more glandular tissue, which is responsible for milk synthesis. This natural difference means one side possesses a greater capacity for milk production, regardless of stimulation.
Behavioral factors, however, amplify this natural imbalance, as breast milk production operates on a supply-and-demand system. If an infant consistently latches more effectively on one side or a parent habitually offers one side first, that breast receives more vigorous and frequent stimulation. This increased demand signals the body to boost supply on that favored side, causing the output gap to widen over time. Differences in milk let-down speed or nipple shape can also cause a baby to develop a preference for one breast, leading to uneven supply.
Techniques for Boosting the Lower-Producing Side
To encourage the lower-producing breast to increase its output, the goal is to maximize stimulation and milk removal from that side. A primary strategy is to always begin the feeding session on the slower side. Infants nurse most vigorously and effectively at the start of a feed when their hunger is highest, providing the strongest signal to increase production on that breast.
You can also employ switch feeding, which involves moving the baby back and forth between the breasts multiple times during a single session. Once the milk flow slows on the lower-producing side, switch the baby to the fuller side until the flow slows again, then return to the less-productive breast. This repeated stimulation encourages multiple let-downs on the side you are trying to boost. Supplementing a feed with a short pumping session on the lower-producing side (five to ten minutes) further signals the body to increase demand and ensures more complete drainage.
Strategies for Managing the Overabundant Side
When one breast is producing too much milk, the focus shifts to reducing the signal for overproduction while maintaining comfort. A common method to regulate a high supply is called block feeding, where you offer only the fuller breast for a specific block of time, such as a three-hour period, even if the baby nurses multiple times. This technique ensures the overabundant side is not fully emptied at every feed, and the remaining milk signals the body to slow down production.
If the unused breast becomes uncomfortably full during a block feeding session, pump or hand express only enough milk to relieve the pressure (pumping for comfort). It is important to avoid fully emptying the breast, as this sends the opposite signal to produce more milk. Applying a cold compress, such as ice wrapped in a thin cloth, between feeds can also help manage engorgement by reducing swelling and signaling a decrease in milk production.
When to Consult a Lactation Professional
While managing supply asymmetry can often be done at home, certain signs indicate that expert help is necessary. If you experience persistent pain, or notice signs of infection such as redness, a fever, or a hard, painful lump that does not resolve, seek medical attention or consult a lactation professional. These symptoms can indicate mastitis or a blocked duct, which requires prompt care.
Consult an International Board Certified Lactation Consultant (IBCLC) if the imbalance is so pronounced that your baby refuses to latch on the slower side. An IBCLC can assess your baby’s latch and milk transfer efficiency, which is crucial if you are concerned about weight gain or overall milk intake. They can provide a personalized plan to safely rebalance your supply.