Breastfeeding hormones
Milk production begins well before the newborn’s first breastfeeding. This process requires changes in the size and shape of the female breast across different stages of development—adolescence, pregnancy, and lactation. Each stage is accompanied by sequential physiological changes. These changes are essential for the successful establishment of milk secretion.
An examination of the female body shows that, starting with adolescence, hormones play a crucial role in preparing for milk production. These hormonal changes also provide certain indications regarding a woman’s future capacity for lactation.
To better understand milk production and its physiology, it is important to study the normal anatomy of breast tissue. The normal breast consists of two main structural components:
- Ducts (the tubular system that transports milk to the nipple)
- Lobules (small glands responsible for milk production)
Different types of lobules are formed during the stages of female development:
- Adolescence: Type 1 lobules are formed. Changes in estrogen and progesterone levels stimulate the development of these lobules during each menstrual cycle.
- Pregnancy: Under the influence of high progesterone levels, alveoli develop. Toward the end of pregnancy, they begin to fill with colostrum.
- Childbirth and lactation: Lobules enlarge further, and milk production becomes active.
- After the cessation of breastfeeding: The mammary glands undergo involution (shrinkage), although complete regression does not occur.
Thus, milk production does not develop solely during pregnancy but, in fact, progresses in a staged manner beginning in adolescence.
The primary organs involved in milk production include:
- Mammary glands (milk production)
- Anterior pituitary gland (secretion of prolactin—milk synthesis)
- Posterior pituitary gland (secretion of oxytocin—milk ejection)
What is prolactin?
Prolactin is the primary hormone responsible for milk production in the body. It is produced mainly in the brain, specifically in the anterior pituitary gland. During pregnancy, due to high levels of progesterone, prolactin cannot become fully active. After childbirth, with the separation of the infant and the placenta from the mother’s body, progesterone levels decrease sharply. At this point, prolactin begins to function actively.
Lisa Marasco and Diana West , in their book “How to Increase Your Milk Supply?”, liken the process of milk production to the launch of a rocket into the sky.
To achieve this, four key conditions are required:
- A well-developed mammary gland
- Sufficient hormonal levels (particularly prolactin and oxytocin)
- Continuous stimulation (breastfeeding or pumping)
- Frequent milk removal (breastfeeding or pumping)
This process is comparable to a rocket launching from its platform into the air. In the initial stage, the rocket requires a large amount of energy (that is, hormones and stimulation) to overcome “gravity” and enter the atmosphere. If this energy diminishes too early or is insufficient from the outset, the rocket will fail to reach its target.
Immediately after birth, frequent and proper breastfeeding or milk expression increases prolactin secretion. It also leads to the formation of a higher number of prolactin receptors. This, in turn, ensures a strong onset of milk production and its long-term maintenance.
To activate the hormone, the infant should be breastfed right after birth (if there are no medical contraindications). Alternatively, the breast should be stimulated through milk expression.
However, let us not forget one important point. Just as prolactin’s role in milk production is essential, the delivery of the produced milk to the infant is equally important. If the milk that is produced does not reach the infant—that is, if it is not removed from the breast—the Feedback Inhibitor of Lactation (FIL) develops. Therefore, especially in the early period, the breasts should be emptied every 2–3 hours. The hormone that assists us in this process is oxytocin.
Oxytocin is the primary hormone responsible for the milk ejection reflex (“let-down reflex”) that enables milk to flow. Immediately after birth, when a mother breastfeeds her infant, oxytocin also facilitates uterine contractions. This hormone is additionally known as the “hormone of love,” and its mechanism of action is highly delicate. For this reason, oxytocin can be inhibited even by minor maternal discomfort or stress. In other words, if the mother is anxious, milk may be produced but not delivered to the infant due to hormonal inhibition. Therefore, breastfeeding in a calm and comfortable environment is of extreme importance.
What factors can interfere with lactation and the breastfeeding process?
• Women who have undergone breast surgery may experience lactation-related difficulties. However, the severity largely depends on the location of the surgical incision. Incisions made through the axilla tend to have less impact on breastfeeding, whereas periareolar “smile-shaped” incisions increase the risk of lactation impairment.
• Breast pathologies in the mother.
• Trauma to the chest area during childhood or adolescence (such as blows, accidents, etc.) may negatively affect future milk production. Such injuries can disrupt the normal development of the mammary glands and milk ducts. Consequently, one may observe insufficient breast growth during pregnancy and reduced milk production after childbirth.
• The mother experiences severe sleep deprivation and extreme fatigue.
• Insufficient breast stimulation due to reliance on artificial feeding.
• Any maternal illnesses that may pose a risk to the mother or the breastfed infant.
• These include the infant’s inability to latch properly, nipple and breast pain, mastitis, blocked milk ducts, and similar issues.
• Maternal mental health.
In summary, milk production is a natural process of the body as a whole. If a woman’s body is capable of carrying a child in the womb, it is fully capable of producing nourishment for the infant as well. Once the mechanism of hormonal action is understood, concerns related to breastfeeding will diminish. This allows the mother to experience the process of nursing with greater ease and enjoyment.
Author: Hajar Piriyeva
Breastfeeding Consultant
