Breastmilk secretion and Lactation Failure

Physiology of Breast Milk Secretion

Breast milk production and secretion are complex physiological processes regulated by hormonal reflexes and local feedback mechanisms.

1. Mammogenesis and Lactogenesis

• Preparation: During pregnancy, the breast prepares for lactation. By the second stage of lactogenesis (typically days 3–10 postpartum), milk production increases significantly.
• Colostrum: In the first 2-3 days, a small quantity (10–40 ml) of colostrum is secreted. It is rich in protein and immunoglobulins.
• Transition: Colostrum is replaced by 'transition milk' in a few days and eventually by 'mature milk'. Milk quantity gradually increases until 6 months.

2. Neuroendocrine Reflexes

Sucking by the baby initiates two primary reflexes essential for establishing and maintaining lactation: the prolactin reflex (milk production) and the oxytocin reflex (milk ejection).

The Prolactin Reflex (Milk Production)

• Stimulus: Sucking acts as the afferent stimulus.
• Mechanism: Sucking stimulates the secretion of prolactin from the anterior pituitary.
• Effect: Prolactin acts on the alveolar cells of the breast to initiate and maintain milk secretion.
• Timing: Frequent emptying of the breast ensures continued prolactin release and milk production.

The Oxytocin Reflex (Let-down Reflex)

• Stimulus: Sucking, or sometimes the sight/cry of the baby, stimulates the posterior pituitary.
• Mechanism: Oxytocin is released into the bloodstream.
• Effect: Oxytocin causes contraction of the myoepithelial cells surrounding the alveoli, forcing milk into the ducts and lactiferous sinuses, making it available to the baby.
• Sensitivity: This reflex is highly sensitive to the mother's emotional state. Anxiety, pain, or stress can inhibit the let-down reflex, whereas a relaxed state enhances it.
• Signs: Trickling of milk from the opposite breast during feeding gives a positive clue that the let-down reflex is active.

3. Local Feedback Mechanisms (Autocrine Control)

• Emptying: Milk production is driven by milk removal. Incomplete emptying leads to the accumulation of feedback inhibitor of lactation (FIL), which suppresses further milk production.
• Hindmilk vs. Foremilk: Continued sucking expresses 'hindmilk,' which is richer in fat and energy compared to the initial 'foremilk'.

Advantages of Breastfeeding: Metabolic Aspects

Breastfeeding offers unique metabolic and biochemical advantages that influence immediate growth and long-term health outcomes, specifically regarding obesity, diabetes, and cardiovascular health.

1. Optimal Growth and Body Composition

• Solute Load: Human milk has a low renal solute load (79 mOsm/L) compared to cow's milk (221 mOsm/L). This ensures a gentle load on the immature infant kidney and prevents hypernatremic dehydration,.
• Protein Quality: Breast milk is whey-predominant (60:40 to 80:20 ratio), whereas cow's milk is casein-predominant (20:80). Whey proteins (lactalbumin, lactoferrin) are easily digestible and provide optimal amino acid profiles without metabolic stress,,.
• Obesity Prevention: Breastfeeding is modestly protective against childhood obesity in a dose-dependent manner.
• Protein-Energy Ratio: The high protein content in formula milk compared to breast milk can lead to excess insulin release, potentially triggering rapid weight gain and adiposity.
• Leptin Regulation: Human milk contains leptin, a hormone regulating appetite and body weight, which is absent in standard formulas. This helps programmed appetite regulation,.

2. Lipid Metabolism and Neural Development

• Essential Fatty Acids (EFA): Breast milk is rich in long-chain polyunsaturated fatty acids (LCPs), specifically Docosahexaenoic acid (DHA) and Arachidonic acid (ARA), which are critical for brain myelination and retinal development,.
• Cholesterol Metabolism: Adults who were breastfed tend to have better cholesterol handling capabilities.
• Carnitine: High levels of carnitine in breast milk facilitate the transport of long-chain fatty acids across mitochondrial membranes for oxidation, essential for energy production in the neonate.
• Enzymatic Support: Breast milk contains Bile Salt Stimulated Lipase (BSSL), which aids in fat digestion and absorption, compensating for immature pancreatic function in infants,.

3. Prevention of Metabolic Syndrome (FOAD)

• Fetal Origins of Adult Disease (FOAD): The "Barker Hypothesis" suggests that early nutrition programs the body for later health. Breastfeeding protects against the "mismatch" between early nutrient deprivation and later abundance, reducing the risk of metabolic syndrome (insulin resistance, hypertension, dyslipidemia),.
• Diabetes Protection: Breastfeeding is associated with a lower risk of Type 2 diabetes and may protect against Type 1 diabetes (Insulin Dependent Diabetes Mellitus),.
• Blood Pressure: Breastfed individuals generally exhibit lower blood pressure and better endothelial function in adulthood compared to those artificially fed.

4. Maternal Metabolic Advantages

• Weight Loss: Lactation increases energy expenditure (approx. 500 kcal/day), helping the mother burn off extra fat accumulated during pregnancy,.
• Uterine Involution: Oxytocin released during breastfeeding aids in rapid uterine involution and decreases postpartum bleeding.
• Cancer Reduction: Breastfeeding decreases the incidence of breast and ovarian cancers in the mother.

Causes of Lactation Failure

Lactation failure can be actual (inability to produce sufficient milk) or perceived (mother thinks she has insufficient milk). It is rarely due to biological inability but often results from management errors.

1. Maternal Factors (Anatomical and Physiological)

• Flat or Inverted Nipples: True inverted nipples retract deeper when compressed, making attachment difficult. However, the baby feeds on the breast tissue, not just the nipple, so this can often be managed with proper technique.
• Sore and Cracked Nipples: Caused primarily by poor attachment where the baby sucks on the nipple rather than the areola. This leads to pain, inhibition of the let-down reflex, and subsequent milk retention,.
• Breast Engorgement: Accumulation of milk and fluid causes hard, painful breasts. This flattens the nipple, making attachment difficult, and back-pressure suppresses milk production (FIL).
• Breast Abscess/Mastitis: Infection or blockage can lead to temporary cessation of feeding from the affected side.
• Systemic Illness: Severe maternal illness or malnutrition (though lactation is remarkably robust even in malnourished mothers).
• Medications: Certain drugs like oral contraceptives (estrogen-containing), thiazides, and bromocriptine can suppress lactation.

2. Infant Factors

• Prematurity: Weak sucking reflex and lack of coordination between sucking and swallowing (before 34 weeks) hinder effective milk removal.
• Congenital Anomalies: Cleft lip or palate can make creating a seal and suction difficult.
• Illness: Sepsis, asphyxia, or other illnesses cause lethargy and poor sucking.
• Nipple Confusion: Use of artificial teats or feeding bottles teaches the baby a different sucking technique, leading to refusal of the breast,.

3. Management and Psychosocial Factors

• Perceived Insufficiency ("Not Enough Milk"): The most common reason for stopping breastfeeding. Often due to lack of confidence or misinterpretation of normal infant behavior (crying) rather than actual low supply.
• Delayed Initiation: Failure to initiate breastfeeding within the first hour of birth.
• Infrequent Feeding: Scheduling feeds rather than feeding on demand leads to decreased prolactin stimulation and reduced milk supply.
• Prelacteal Feeds: Giving sugar water, honey, or animal milk satisfies the baby's thirst/hunger, reducing the vigor of sucking at the breast and carrying infection risks.
• Incorrect Positioning and Attachment: The most critical technical cause. Poor attachment leads to inefficient milk transfer, sore nipples, and eventual failure,.
• Lack of Support: Psychological stress, anxiety, and lack of family support inhibit the oxytocin reflex,.
• Early Lactation Failure (ELF) Syndrome: A condition described where abrupt stoppage of breastfeeding and early introduction of dilute starch-based diets leads to severe malnutrition (marasmic kwashiorkor) in young infants.