Will this imbalance affect my baby’s nutrition?

Not usually. As long as your baby is gaining weight and having regular wet diapers, the total milk intake is likely adequate, even if it’s mostly from one breast.

Can this cause permanent asymmetry in my breasts?

Temporary size differences may occur during lactation, but they often balance out after weaning. Some asymmetry may remain, but it’s rarely noticeable or problematic.

Should I stop using the stronger side to balance things out?

No. Limiting the fuller side can lead to engorgement or mastitis. Instead, try increasing stimulation on the lower-producing side.

Is it okay to feed from one side only?

Yes, in some cases. If one breast is significantly under-producing and the baby refuses it, exclusive feeding from one breast is possible, with close monitoring.

One Breast Producing Less Milk? Causes, Tips & When to Worry

Even if you're doing everything right, nursing frequently, staying hydrated, and eating well, one breast might still seem to lag behind the other in milk production. Maybe your baby favours one side. Maybe you notice a visible size difference or more leaking from one side. This imbalance can feel unsettling, especially if you’re anxious about supply or worried about giving your baby enough milk.

But here’s the reassuring truth: it’s not just you. Almost all lactating individuals produce more milk from one side than the other. It's a normal, physiological variation rooted in anatomy, milk duct distribution, and even your baby’s preferences. Knowing the difference between what’s normal and what might need support can make breastfeeding less stressful and more intuitive.

It’s called asymmetrical milk production, when one breast makes noticeably more milk than the other.
This doesn't mean there's something wrong with your milk or your body. The size of your breasts, the number of milk ducts on each side, and how your baby feeds can all influence how much milk each breast produces.

Most people have one dominant breast, the “better producer,” and one that makes less. The difference can be mild or significant, but it rarely means your overall supply is insufficient.

Why It Matters: Supply, Comfort, and Confidence

Mild asymmetry doesn’t typically interfere with feeding. But when the difference becomes more pronounced, it can affect your experience in several ways:

Worry About Baby's Intake: You may wonder if your baby is getting enough milk, especially if they strongly prefer one breast or fuss at the slower-producing side.
Uneven Breast Size or Fullness: Visibly different fullness levels or leaking patterns can make you feel self-conscious or uncomfortable, particularly in public or tight clothing.
Blocked Ducts or Engorgement Risk: Overreliance on one breast can cause engorgement or plugged ducts in the fuller breast, while underuse of the other can risk supply reduction.
Breastfeeding Confidence: If you’re struggling with uneven output while pumping, it can shake your confidence in your ability to provide enough for your baby.

What Causes Uneven Milk Production?

Several normal and medical factors can influence how much milk each breast produces:

Baby’s Feeding Preference: Babies may latch more effectively or nurse longer on one side, stimulating more milk production there.
Milk Duct Distribution: The number of milk ducts varies naturally between breasts, and one side might simply be structurally more efficient.
Positioning and Latch Issues: Poor latch on one side can reduce stimulation and milk removal, leading to lower supply.
Previous Injury or Surgery: Biopsies, implants, or trauma can damage ducts or nerves in one breast, impacting milk output.
Mastitis or Inflammation: An infection or blocked duct in one breast can reduce supply temporarily or long-term.
Posture and Holding Habits: You might unconsciously prefer holding your baby a certain way, reinforcing one side's dominance.

How Is It Assessed?

There’s no formal test for milk supply imbalance unless symptoms raise concern. Assessment usually includes:

Observation of Baby's Feeding Behaviour: Does your baby feed equally well on both sides or fuss on one? How long are they nursing? Are they gaining weight appropriately?
Pumping Output Comparison: If you pump, note how much milk you express from each side. A small difference is normal, but a consistent 2:1 or greater difference may warrant guidance.
Visual and Physical Checks: Your lactation consultant or doctor may examine for blocked ducts, nipple shape variations, or breast tissue differences.
Ultrasound or Mammography (if needed): In rare cases, imaging is used to rule out structural issues or masses affecting milk flow in one breast. Always consult your doctor before pursuing this.

Ways to Balance Milk Supply Between Breasts

If the difference in output is mild, you may not need to change anything. But if it’s causing concern, here are some supportive options:

Start Feeds on the Lower-Producing Side: Babies feed more vigorously at the start of a session, which stimulates supply. Starting on the lower-producing side can help boost its output.
Pump After Feeds: Use a breast pump for 5–10 minutes after feeding on the lower-producing breast to stimulate more milk production.
Breast Compressions: Gently compress the breast during nursing or pumping to encourage flow and maintain the baby’s interest.
Improve Latch: Work with a lactation consultant to troubleshoot any latch or positioning issues that might be limiting milk transfer on one side.
Offer Both Breasts at Each Feed: Ensure the baby gets time on both sides, even if they seem satisfied with the first. Gentle encouragement can slowly shift preferences.

Never force-feed from the lower-producing breast if your baby is refusing strongly or if it causes distress. Gentle guidance and consistency work better than pressure.
Having one breast that produces less milk is a common occurrence. It’s usually harmless. With gentle support, smart strategies, and professional help when needed, you can navigate this imbalance without panic. Trust your body, watch your baby’s cues, and remember: breastfeeding isn’t about perfection, it’s about connection and care.

FAQs on One Breast Produces Less Milk Than the Other: Is That Normal?

Will this imbalance affect my baby’s nutrition?
Not usually. As long as your baby is gaining weight and having regular wet diapers, the total milk intake is likely adequate, even if it’s mostly from one breast.
Can this cause permanent asymmetry in my breasts?
Temporary size differences may occur during lactation, but they often balance out after weaning. Some asymmetry may remain, but it’s rarely noticeable or problematic.
Should I stop using the stronger side to balance things out?
No. Limiting the fuller side can lead to engorgement or mastitis. Instead, try increasing stimulation on the lower-producing side.
Is it okay to feed from one side only?
Yes, in some cases. If one breast is significantly under-producing and the baby refuses it, exclusive feeding from one breast is possible, with close monitoring.