The Role of Oxytocin in Breastfeeding

Julie · September 15, 2021
Oxytocin is a very important hormone during postpartum. Today, we'll talk about the role of oxytocin in breastfeeding

Oxytocin is a key hormone for breastfeeding, although it’s not the only hormone involved in the process. The main role of oxytocin in breastfeeding is to ensure the ejection of milk through the breasts when the baby sucks and to trigger the mechanisms necessary to sustain the supply throughout breastfeeding.

Have you ever heard of its importance in the postpartum period? In this article, we’ll tell you about the benefits it offers for both mother and baby.

Preparing the body for breastfeeding

During pregnancy, a woman undergoes many changes in her body that prepare her for the birth of her baby. These include all the changes in the structure of the breasts necessary for producing breast milk (lactogenesis).

As early as the 16th week of gestation, breast fat begins to be replaced by glandular tissue, which is specialized in the production of milk. This tissue consists of producing elements (called alveoli) and releasing ducts (called lactiferous ducts).

In addition to these changes, the network of blood vessels around these structures will become denser in order to increase the blood supply to the breast and provide sufficient nutrients for milk production.

Towards the end of pregnancy…

During the third trimester of pregnancy, the gland is sufficiently developed and begins to produce a natural fluid called colostrum. This is the first source of nourishment for the newborn.

While the child doesn’t yet need it, because they haven’t been born, it’s part of the initiation of breastfeeding. Progesterone will be the hormone in charge of maintaining this slow production until the end of gestation.

After birth, more specifically with the expulsion of the baby and the placenta, the second phase of the lactogenesis process begins. At this time, there’s an abrupt drop in progesterone in the blood, which frees the mammary gland to produce milk.

From this moment on, there are two postpartum hormones that regulate the lactation process: Prolactin and oxytocin.

The role of oxytocin in lactation

The role of oxytocin in breastfeeding is key to success, as it ensures that the gland expels the milk it produces.

While suckling, the baby exerts pressure on the nipple and areola in order to express the milk in the breast. The coordinated movement of their mouth produces a negative pressure within the milk ducts to empty them, causing them to collapse once they release the milk.

Oxytocin is responsible for contracting the cells surrounding the acini and milk ducts to ensure that the ducts are re-deployed and fill with milk again. This way, milk supply to the baby continues throughout lactation.

Like prolactin (the hormone responsible for milk production), nipple stimulation causes the release of oxytocin during suckling or by manual milk expression maneuvers.

However, unlike prolactin, visual, auditory, or emotional stimuli having to do with the baby also cause the release of oxytocin.

This is an amazing phenomenon of nature, which experts presume has to do with the maternal behaviors necessary for successful breastfeeding.

A mother holding her crying newborn.

Factors conditioning oxytocin release

Stimulation of a brain area closely that has to do with the regulation of emotions, called the hypothalamus, produces oxytocin. When this is activated, it sends signals to the pituitary gland to produce different hormones. This includes those that take part in the breastfeeding process.

These hormones will travel through the blood to the mammary gland to stimulate those cells in charge of milk production (prolactin) and release (oxytocin).

The stimuli for oxytocin release are numerous and have to do with the maternal behavior necessary for caring for offspring.

For example, when the baby cries, the maternal organism begins to prepare to offer food to satisfy the baby’s hunger. The same happens when the mother sees or thinks of her baby. This is because the ultimate goal of this hormonal process is to ensure permanent contact between mother and child from the first hours after birth.

Experts have discovered that the occurrence of negative emotional factors such as stress, pain, and even maternal depression could inhibit the secretion of oxytocin and condition the success of lactation.

For this reason, it’s important to offer mother and baby a calm environment during the first hours. This ensures that the entire hormonal circuit works harmoniously.

Other benefits of oxytocin

In addition to its action on the release of breast milk, experts have discovered other benefits having to do with this hormone during lactation and postpartum. So, we can say that oxytocin does the following:

  • Favors the release of prolactin, which is the hormone in charge of producing milk
  • Decreases maternal stress levels
  • Regulates the mother’s blood pressure within appropriate levels
  • Stimulates the maternal parasympathetic nervous system, involved in functions such as food digestion and intestinal transit
  • Provokes postpartum uterine contractions so that this organ recovers its original size
  • Reduces postpartum bleeding
  • Facilitates the process of mental adaptation to motherhood
  • Reduces postpartum anxiety
  • Improves the mother’s social interaction with her environment

According to data from animal studies, oxytocin could be strongly related to maternal behaviors of offspring preservation.

A mother embracing her newborn.


The role of oxytocin in breastfeeding is essential to adapting to motherhood. It’s not only a protagonist in lactation. It also plays an important role in the mother’s emotional regulation by mediating the attachment bond with her baby.

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