Does Breast Size and Shape Affect Milk Production?

by Sabrina Granniss, IBCLC April 25, 2022

different breast sizes

Large breasts, small breasts, uneven breasts, perky breasts, saggy breasts, and all breasts in between are beautiful!

Your breasts are designed by nature to produce milk and sustain your baby’s life. The development of your breasts begins when you are just the size of a plum in your mother’s uterus. Your breasts go through several stages of development in puberty, pregnancy, lactation, and finally menopause.

Breast development

In utero - the mammary ridge or milk line begins to develop in the fetus in the first trimester. The beginning ductal system form and nipples develop during the rest of pregnancy.
Preadolescence - breasts are flat except for the nipple is more raised
Puberty - Breast buds begin to develop between the age of 8-and 13. The areola begins to widen and the nipple becomes more raised. When the ovaries secrete estrogen, the ductal system begins to grow and fatty tissue increases and the breasts become larger. The first period is usually 2-3 years after the onset of puberty.(1)
Ovulation begins, menstruation begins and lobes form at the base of the ducts(2) containing lobules that synthesize and store milk.
Pregnancy - your areola may become darker and your breasts more tender as your breasts prepare to begin making colostrum for your baby. Breast size increases and the veins on your chest become more visible. The Montgomery glands develop and look like little bumps on your areola. An increase in estrogen levels signals the milk duct system to grow and branch out. Estrogen communicates with the pituitary gland to increase prolactin for making milk. Higher levels of estrogen and progesterone suppress milk from being released.(3)
Birth - The Montgomery glands secrete a fluid that smells like amniotic fluid which helps your baby find their way towards your chest after they are placed skin to skin on you after birth.
Lactation - As soon as the placenta is separated from the uterus and birthed, progesterone and estrogen drop considerably and prolactin levels rise to trigger milk production. Over the next 2-3 days milk supply will increase in volume compared to colostrum. Over the next few weeks, the milk supply begins to regulate based on the information it receives. Demand dictates the supply.(4)
Perimenopause & Menopause - Levels of estrogen drop and your breasts become less elastic due to a loss of hydration in your breast’s connective tissue. Glandular tissue decreases and your breasts may change their shape or lose some of their firmness. Going braless encourages your chest muscles to be more engaged and may prevent sagging. Did you know that even after your body goes through menopause, you are capable of producing milk? In some cultures, grandmothers lactate to feed a family member’s newborn for various reasons.(7) As long as the pituitary gland is functioning properly, it is possible to relactate.

Anatomy of the lactating breast

The amount of glandular tissue that develops influences the amount of milk someone can make. Each breast has 15-20 lobes that resemble a bunch of grapes. Inside them are cells that synthesize milk, pulling nutrients from the blood supply into the cell to make milk.

Goat’s rue is an herb in Legendairy Milk’s Liquid Gold, Lechita, and Cash Cow that can increase the amount of tissue able to make and store milk.

The amount of fatty tissue someone has is what determines breast shape size. Fat in the breast is not part of the milk-making system. The amount of fatty tissue varies tremendously between people. Some people have 50% fatty tissue, while others have closer to 20% which explains why we all have various sizes and shaped breasts.(5)

How milk supply works

When you put your baby on your body, especially skin to skin, the hormone oxytocin is released. It squeezes the lactocyte cells lining the alveoli, releasing milk that flows through the ducts towards your nipple.(8)

Sucking, nipple stimulation and milk being removed elevates prolactin levels sending the message from the pituitary gland to make more milk. So, as your baby nurses and is emptying the milk in the alveoli, more milk is being made and stored simultaneously.

Using the Breast-Ease heat pack before nursing or pumping can help encourage the flow of milk and increase how much milk can be removed, increasing milk production.

The more often milk is being removed, the more often milk is being made. The process of making milk is continuous. Going longer periods between nursing sessions and not removing milk sends the message to slow down the production and some cells may stop synthesizing and storing milk altogether.

When the baby nurses or milk is removed by hand expression or pumping, prolactin levels rise and signal milk to continue to be made. Prolactin is highest during the middle of the night. Removing milk between 2-5 am, when levels are already elevated, has a huge impact on maintaining the overall milk supply.(6) Older babies are often busy exploring their world during the day and nurse less often but make up for it during the night making overnight breastfeeding just as important for them as it is for younger babies.

Some moms can go longer between milk removals if they happen to have more breast tissue. Other people will need to nurse their babies more often if they have less storage capacity. The minimum number of milk removals per 24 hours is 8-10 to be able to meet their babies' needs. When following the babies' cues, it is biologically normal for them to nurse at least 12 times per day, but often even more than that.

When to get help

If you are concerned about your milk supply, reach out to your IBCLC to help you investigate more to figure out what the root cause is. They can help with positioning at your chest as well as how well your baby can do their part of latching deeply and effectively removing milk.

By taking a complete health history, you may connect the dots leading to hormone dysregulation reasons for your supply being low or breastfeeding management strategies to improve your milk output and supply.

Your IBCLC can help co-create a personalized care plan you are comfortable with and reach your breastfeeding goals.