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Mother Baby Bonding
Kayla Abrego, MSc & Kelsey McLaughlin, PhD

Breastfeeding is the feeding of an infant with breastmilk, typically directly from the breast. Breastfeeding is unique to each woman and child.

Keep reading to learn more about breastfeeding. 

Breast structure

The human breast is a complex organ that is made up of different types of tissues, blood vessels, lymph nodes and ligaments. An important component of the human breast is a network that produces breastmilk and carries the breastmilk to the nipple.

The breast contains about 15 to 20 sections that are called lobes. Each lobe branches out into smaller lobules, which contain tiny bulbs. During pregnancy, these bulbs develop milk-secreting cells called lactocytes. Small tubes called ducts create a network to connect the lobes and lobules, and carry breastmilk toward the areola, which is darkened skin in the center of the breast. Large ducts carry breastmilk from the areola to the nipple. Breastmilk is released from the nipple when the infant suckles, with pumping or with expression.

The growth of lobes and lobules during pregnancy cause breasts to increase in size.

The space between the lobules and ducts in the breast is filled with fat tissue.

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How is breastmilk produced?

The production of breastmilk is a two-phase process called lactogenesis: 

  • Phase I: occurs during pregnancy when the cells of the breast change shape and function to produce breast milk

  • Phase II: occurs after birth when breastmilk is secreted

The production and secretion of breast milk is controlled through hormones.


During pregnancy, the placenta and ovaries secrete large amounts of estrogen and progesterone that enter the pregnant woman's blood and circulate around her body. Levels of prolactin, a hormone that is produced in the brain, are also high in the woman's blood during pregnancy. These hormones prepare the breast for breastfeeding, by increasing the size of the breast lobules and ducts. High levels of estrogen and progesterone also prevent the breast from producing and secreting breastmilk during pregnancy.

Following delivery, levels of estrogen and progesterone in the mother's blood drop, while prolactin levels in the blood remain high.

The production of breastmilk is maintained by infant suckling, pumping or the expression of breast milk (expression typically refers to squeezing milk out of the breast manually)
. The suckling action on the breast sends a message to the mother's brain, causing her brain to release the hormones prolactin and oxytocin into her blood to circulate around her body. Prolactin stimulates the breast tissue to produce milk, while oxytocin makes cells in the breast contract to stimulate the release of already-made breastmilk from the breast (also known as the 'let-down' reflex).


In addition to infant suckling, the let-down reflex can also be triggered in the mother when she uses a breast pump, sees the baby, or hears the baby cry.

In the week following delivery, the amount of prolactin in the mother's blood decreases. If women wish to continue breastfeeding, high amounts of prolactin and oxytocin must be maintained in her system to support the production and release of breastmilk through consistent suckling, pumping or expression. Breastmilk availability is based on a supply-and demand process. 

In other words, women must use it or will lose it.

Nursing Newborn
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Breastfeeding recommendations

Leading medical authorities, including Heath Canada, Canadian Paediatric Society, and World Health Organization, recommend exclusive breastfeeding until the infant is six months of age. Women are recommended to continue breastfeeding until two years of age, or as long as the mother and infant desire. 

A recent Canadian study found that over 90% of women attempted breastfeeding in the first few hours following delivery. At six months postpartum, 40% of Canadian women were still exclusively breastfeeding.

As breastfeeding is widely recommended by medical professionals, women can feel significant pressure to breastfeed their infants. However, many women who try to breastfeed face challenges. Not every woman is able to or chooses to breastfeed their infant. The top priority during the newborn period is to ensure that infants are properly nourished, regardless of nutrition source (breastmilk or formula supplementation), and to ensure that women and their infants are healthy and happy.

Benefits of breastfeeding

Research has shown that breastfeeding has a positive impact on the health of both mom and baby.

Maternal benefits of breastfeeding

Short-term breastfeeding benefits​ include:

Long-term breastfeeding benefits include decreased risk of:

  • Type 2 diabetes

  • Hypertension and other cardiovascular diseases

  • Breast and ovarian cancer

Infant benefits of breastfeeding

Short-term breastfeeding benefits​ include decreased risk of:

  • Ear infection (acute otitis media)

  • Severe lower respiratory tract infections 

  • Gastroenteritis

  • Sudden infant death syndrome (SIDS) 

Long-term breastfeeding benefits include decreased risk of:

Discontinuation of breastfeeding 

There are many reasons why women may discontinue breastfeeding before the recommended six-month period, referred to as early breastfeeding discontinuation. A Canadian study found that the most common reasons for early breastfeeding discontinuation was fatigue and/or inconvenience (23%) and perception of insufficient milk supply (22%).  

Other risk factors include:

  • Delayed milk production, defined as when plentiful milk secretion is delayed at least 72 hours after birth

  • Early supplementation with formula

  • Pregnancy complications 

  • Physical pain when breastfeeding

  • Maternal ethnicity

  • Need to return to work 

  • Low maternal confidence 


Women are more likely to exclusively breastfeed in future pregnancies if they have positive and successful breastfeeding experiences from previous pregnancies. A Canadian study found that women who have been pregnant before are more likely to exclusively breastfeed to six months, due to increased knowledge and self confidence in breastfeeding from their previous pregnancy. 

When is breastfeeding not recommended?

There are certain circumstances when breastfeeding is not recommended. Women on medications, undergoing medical procedures, or with health concerns are recommended to speak to their doctors about breastfeeding safety.


This can include:


  • Women with human immunodeficiency virus (HIV), Ebola virus disease or untreated tuberculosis 

  • Women who use illicit drugs  

  • Infants who have been diagnosed with galactosemia 

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Newborn Baby

Breastfeeding support


Women are more likely to meet their breastfeeding goals with appropriate care and support. The Public Health Agency of Canada offers ten tips for successful breastfeeding, including how to tell a baby is wanting to feed, looking after mom and talking to others if there are questions or worries.

There are many resources available to women that provide breastfeeding support, in addition to health care providers and lactation consultants. La Leche League Canada is a registered non-profit that provides mothers and new parents with evidence-based information to support breastfeeding goals.



Breastfeeding provides numerous benefits for both mother and infant. Many women discontinue exclusive breastfeeding earlier than the recommended six months due to breastfeeding difficulties. With proper breastfeeding support and education, mothers may feel more confident in overcoming breastfeeding difficulties and continue to breastfeed for longer durations. Overall, the top priority during the newborn period is to ensure that infants are properly nourished, regardless of nutrition source.


Every woman and every pregnancy is unique. Pregnant women should speak to their healthcare provider to ensure maternal and fetal safety. This article is meant to provide readers with current information and opinions. All medical and treatment decisions should be discussed with your healthcare provider.

This article was written by Kayla Abrego and Dr. Kelsey McLaughlin and edited by Dr. Kelsey McLaughlin and Dr. Melanie Audette.

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