What Is ‘Breast Milk Storage Capacity,’ And Can I Increase Mine?

Breastfeeding is a complex process that every parent experiences differently. One’s breastfeeding journey can change over time and vary from one baby to the next.

And to make matters more confusing, there’s a lot of unfamiliar jargon in the breastfeeding space. One term that often crops up is “breast milk storage capacity” or “breast storage capacity.”

To help demystify this phrase, we asked breastfeeding experts to break it down for nursing parents and parents-to-be.

What is breast storage capacity?

“Breast storage capacity is how much milk is available when breasts are the fullest,” said Dr. Emily Huffstetler, a board-certified OB-GYN and adviser for Share the Drop. “It has nothing to do with breast size, but rather the room in the glandular tissue ― where milk is produced.”

Because breast storage capacity has nothing to do with the size of one’s breasts, a mother with small breasts could actually have a higher capacity than one with larger breasts.

“Women vary dramatically in their breast storage capacity,” said Carole Kramer Arsenault, a registered nurse and founder of Boston Baby Nurse & Nanny. She noted that two studies found mothers to have a breast storage capacity range of 74 grams to 660 grams, or 2.6 ounces to 23.3 ounces.

It’s possible to have breasts with two different storage capacities as well.

“It also has nothing to do with the total amount of milk being produced, commonly called ‘supply,’” noted Susan Mocsny Thomas, a registered nurse and professional liaison department administrator with La Leche League Alliance. “Breast storage capacity is the amount of milk in the breast at the beginning of each feeding. If your breast capacity is on the lower side, your baby may need to breastfeed more frequently. The amount of milk needed will still be produced, but since there is not as much storage room, your breasts will fill more frequently, and baby may want more frequent feedings.”

If your storage capacity is larger, your breasts may not reach that “full” stage as quickly, and your baby may require less frequent feedings, she added.

It’s important to note that not everyone in the breastfeeding community is on board with the idea of “breast storage capacity.”

“I would emphasize that ‘breast storage capacity’ is not a medical or scientific term,” said Dr. Sheela Rath Geraghty, co-director of the Cincinnati Children’s Center for Breastfeeding Medicine and medical director of the Cincinnati Children’s Breastfeeding Medicine Clinic.

She explained that all babies drink different amounts of milk from the breast at each feeding. The idea that babies should always consume the same amount of milk is based on bottle feeding and is “not physiologically normal.”

“There is no way to say that a mother will ever get the same out of the breasts each time that they have milk extracted from their body, whether by a pump or a baby,” Geraghty said. “We as people eat different amounts each time we eat. Breastfed babies extract different amounts of milk from the breast every time that they eat as well.”

Can breast storage capacity be increased?

“It’s not possible to increase your storage capacity since it is physical, but again, it does not have to do with the amount of milk you produce,” Thomas said.

Interestingly, multiple experts noted that there is some anecdotal evidence of storage capacity increasing in subsequent pregnancies. But that has not been adequately studied and would be outside a parent’s control anyway.

“Some women notice a slight increase in milk capacity with additional pregnancies,” Arsenault said. “If a mom is diagnosed with insufficient glandular tissue, it is still possible to breastfeed, but she will likely have to get creative and augment the feedings.”

Should nursing parents even think about this?

Breast storage capacity “does not need to be a concern of breastfeeding parents,” Thomas said. “If anything, it’s an incidental finding, where you might think, ‘Hm. My baby seems to breastfeed on the frequent side. Maybe my breast storage capacity is on the smaller side,’ or, ‘Huh. My baby is gaining well, but seems to nurse less frequently than I expected. Maybe my breast storage capacity is on the larger side.’”

She explained that feeding according to your baby’s cues is what matters and will ensure that they’re getting enough to eat.

“As long as baby has the number of wet and dirty diapers expected and is gaining well, it is of no concern what your storage capacity is,” Thomas said.

Between the recent formula shortages and guidance from certain breastfeeding blogs, many parents feel added pressure to produce even more milk and have a deep “stash” in their freezers.

But Geraghty warned that this pressure can lead them to pump too frequently and possibly develop engorgement and mastitis in the process. Don’t concern yourself with what you think your breast storage capacity is or try to “compensate” by nursing or pumping more than necessary.

“What makes a mother feel accomplished at feeding her baby is when she is successful at making the right amount of milk for her baby,” Geraghty said. “A breastfed baby’s behavior should be watched closely ― when the baby is satisfied and full, the baby will be calm. If the baby did not eat enough, the baby will be fussy and want to go back on the breast and be fed more.”

If you aren’t producing enough milk to satisfy your baby or are having trouble effectively latching, seek help from a professional. Together, you can find research-backed solutions and figure out what works best for you and your child.

“The concept of breast storage capacity reiterates that each woman’s body is different and each woman’s breastfeeding journey will be different,” Huffstetler said. “Knowing your own body and what your own baby needs is an important part of every woman’s breastfeeding journey.”