Does Breast Size and Shape Affect Milk Production?

Written by: Sabrina Granniss, IBCLC

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Time to read 5 min

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. Development of your breasts begins when you are just the size of a plum in your mother’s uterus and 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 ages 8-13. The areola begins to widen, and the nipple becomes more raised. When the ovaries secrete estrogen, the ductal system begins to grow, fatty tissue increases, and the breasts become larger. The first menstrual 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 toward your chest when 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, the 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 correctly, 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 that can increase the amount of tissue able to make and store milk.

Goat’s rue is in the following Legendairy Milk lactation supplements

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% adipose tissue, while others have closer to 20%, which explains why we all have various sizes and shaped breasts. (5)

How milk supply works

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


Sucking, nipple stimulation, and removing milk elevate prolactin levels sending the message from the pituitary gland to make more milk. So, as your baby nurses and empties 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 milk flow and increase how much milk can be removed, increasing milk production.


The more often milk is removed, the more often milk is being made. The process of making milk is continuous. Going longer stretches of time 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 prolactin levels are already elevated significantly impacts 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 are able to 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 meet their baby's needs. When following the baby's 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, contact your IBCLC (International Board Certified Lactation Consultant) to help you investigate more to determine the root cause. They can help with breastfeeding positioning and assess your baby’s ability to 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 you co-create a personalized care plan you are comfortable with and support you in reaching your breastfeeding goals.


Every woman’s breasts are unique and beautiful, regardless of their size, shape, or color. Breast development starts in utero and progresses through puberty, pregnancy, lactation, and menopause. During lactation, milk production and supply depend on the amount of glandular and fatty tissue in the breast, as well as the hormone oxytocin and prolactin, which are released when the baby nurses or milk is removed. To maintain a good milk supply, it is essential to nurse often and remove milk regularly. Understanding the anatomy and function of the breasts can help new mothers successfully breastfeed their babies and appreciate the beauty and wonder of their own bodies.

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