Breastfeeding Through the Lens of Evidence-Based Medicine

1. Myth: If the baby is constantly attached to the breast, the milk must be watery or low in fat

Scientific fact: The composition of breast milk is dynamic, and feeding frequency is regulated by the infant’s needs, not by the milk’s fat content.

From a biochemical perspective, breast milk is not uniform over the course of a single feed.

• The foremilk fraction is rich in lactose and water. Its role is to provide hydration and a quick source of energy for the brain.
• The hindmilk fraction is released progressively as the lobule of the mammary gland is emptied. It contains 1.5 to 2 times more lipids than foremilk. These lipids are what provide satiety and higher caloric density.

Physiology: Breast milk is digested much faster than formula, typically within 40 to 60 minutes, due to the presence of lipase and its optimal protein profile. Frequent nursing is normal infant behavior driven by rapid metabolism and the need for contact, including co-regulation of the nervous system, rather than a sign of hunger or poor-quality milk.

2. Myth: Formula-fed babies get sick less often than breastfed babies, so the immune benefits of breastfeeding are a myth

Scientific fact: Breast milk is not just nutrition; it is an immunologically active substance. Formula lacks this biological activity.

Breast milk contains components that cannot be replicated artificially:

• Secretory immunoglobulin A (sIgA): Coats the infant’s intestinal mucosa and creates a barrier against pathogens.
• Lactoferrin: A protein with direct antibacterial, antiviral, and antifungal properties.
• Human milk oligosaccharides (HMOs): Prebiotics that are not digested by the infant but instead serve as substrates for Bifidobacterium infantis, beneficial bacteria involved in shaping the gut microbiota.

Epidemiology: Research, including The Lancet Breastfeeding Series, confirms that breastfeeding reduces the risk of acute otitis media, severe respiratory tract infections, and gastroenteritis.

If a particular breastfed infant still becomes ill, this is due to genetics and environmental factors. However, statistically, without breastfeeding, both the severity and the incidence of these illnesses would be higher.

3. Myth: If a baby is crying in the maternity ward, they must be hungry, their stomach is empty, and they need formula

Scientific fact: A newborn’s stomach has an extremely small physiological capacity, and colostrum is a highly concentrated source of energy.

The anatomical capacity of a newborn stomach is very small:

• Day 1: 5 to 7 mL, about the size of a cherr
• Day 3: 22 to 27 mL, about the size of a walnut

In the first days after birth, the mammary gland produces colostrum. This is a thick fluid rich in protein and immune factors but produced in small volumes. That volume is perfectly matched to the size of the newborn stomach and does not overload the infant’s immature kidneys with excess fluid.

Physiological weight loss: A loss of up to 10% of body weight during the first days of life is considered normal due to fluid shifts and meconium passage. Formula supplementation is a medical intervention and is indicated only when weight loss exceeds 10% or when there are signs of clinical dehydration, according to Academy of Breastfeeding Medicine protocols.

4. Myth: Drink cow’s milk and eat fatty foods to make your breast milk richer

Scientific fact: Milk synthesis, or lactogenesis, occurs from components derived from the blood and lymph, not directly from the contents of the mother’s stomach.

The mammary gland acts as both a filter and a factory. The major macronutrients in breast milk — proteins, fats, and carbohydrates — remain relatively stable because this composition is essential for species survival.

• If the mother consumes too little fat, her body will mobilize fat stores from her own tissues to produce milk.
• Dietary fat intake may slightly alter the fatty acid profile of the milk, but not its total fat content to any major degree.

Risks: Excessive consumption of whole cow’s milk by the mother is a risk factor for cow’s milk protein allergy (CMPA) in the infant. Cow’s milk proteins can pass into breast milk and trigger an immune response, including proctocolitis and blood in the stool. The evidence-based recommendation is a varied, balanced diet without forced consumption of dairy products.

5. Myth: Breastfeeding will ruin the shape of the breasts and make them sag

Scientific fact: The main risk factor for breast ptosis is pregnancy, not lactation.

Research cited by the American Society for Aesthetic Plastic Surgery, now The Aesthetic Society, has shown that breastfeeding is not an independent risk factor for breast ptosis.

What actually affects the Cooper’s ligaments, the structural support of the breast:

• Pregnancy: A rapid increase in breast volume and the hormone relaxin stretch the skin and ligaments even before delivery.
• BMI: Weight fluctuations
• Age: Natural decline in skin elasticity
• Smoking: Damages elastin in the skin

Mammary gland involution, meaning the regression of breast tissue after pregnancy, occurs regardless of whether a woman breastfeeds or suppresses lactation pharmacologically.

Suggested references:

1. WHO (World Health Organization): Breastfeeding guidance
2. American Academy of Pediatrics (AAP): Policy Statement on Breastfeeding
3. Academy of Breastfeeding Medicine (ABM): Clinical Protocols