Breastfeeding and Lactation

Breastfeeding is the feeding of an infant with milk directly from the breast, and lactation is the physiological process by which the mammary gland produces and secretes that milk. Human milk is the biological norm for infant feeding, supplying not only macronutrients but bioactive and immunological components, and for preterm and sick newborns mother's own milk has particular protective value.

Definition

Breastfeeding is the provision of human milk to an infant directly from the breast; lactation is the hormonally regulated synthesis and secretion of milk by the mammary gland that makes breastfeeding possible.

Scope

This topic covers the physiology of lactation, the composition and bioactive properties of human milk, the concept and rationale of exclusive breastfeeding, and the special role of human milk — including donor milk — in the preterm infant. It situates breastfeeding within neonatal nutrition as a reference subject and does not provide individual lactation counselling or clinical protocols.

Core questions

• How is lactation initiated and maintained physiologically?
• What components of human milk distinguish it from formula, and why do they matter?
• What is exclusive breastfeeding, and what is the evidence on its optimal duration?
• Why is human (including donor) milk emphasized for preterm and low-birth-weight infants?

Key concepts

• Lactogenesis
• Prolactin and oxytocin (milk synthesis and let-down)
• Colostrum and mature milk
• Human milk bioactive and immune factors
• Exclusive breastfeeding
• Mother's own milk versus donor human milk
• Lifelong effects of breastfeeding

Mechanisms

Lactation proceeds through mammary development in pregnancy, secretory differentiation around delivery (lactogenesis), and ongoing milk production sustained by infant suckling. Prolactin drives milk synthesis and oxytocin triggers the milk-ejection (let-down) reflex, while continued milk removal maintains supply. The resulting milk delivers stage-appropriate macronutrients together with immunoglobulins, oligosaccharides, growth factors, and live cells that support gut maturation and host defense — properties that underlie the observed associations between breastfeeding and reduced infection and, in preterm infants, reduced necrotizing enterocolitis.

Clinical relevance

Breastfeeding and the use of human milk are central to neonatal nutrition, and for preterm infants mother's own milk is associated with lower rates of feeding-related complications. This entry describes those relationships and the supporting evidence as reference material; it is not lactation counselling and does not give individualized feeding instructions.

Epidemiology

Breastfeeding prevalence and duration vary widely across countries and socioeconomic groups, and global analyses link higher breastfeeding rates to substantial reductions in infant infectious morbidity and mortality. In neonatal units, access to mother's own milk and to pasteurized donor milk has become a measured quality indicator for preterm care.

History

Human milk has always been the default mode of infant feeding, but its scientific characterization — the hormonal control of lactation, the bioactive composition of milk, and the quantified health effects of breastfeeding — accumulated through twentieth- and twenty-first-century research. Successive systematic reviews and professional statements consolidated recommendations on exclusive breastfeeding and on prioritizing human milk for vulnerable newborns.

Debates

How long should exclusive breastfeeding continue?

Evidence reviewed in Cochrane work supports about six months of exclusive breastfeeding in most settings, but the balance of benefits in specific populations and circumstances continues to be examined and refined.

Seminal works

• victora-2016
• kramer-2012
• aap-2012

Frequently asked questions

What is the difference between breastfeeding and lactation?

Lactation is the physiological process by which the breast produces and secretes milk; breastfeeding is the act of feeding that milk to the infant directly from the breast.

Why is human milk especially emphasized for preterm infants?

Mother's own milk supplies bioactive and immune components that support the immature preterm gut and is associated with lower rates of necrotizing enterocolitis; when it is unavailable, pasteurized donor human milk is often preferred over formula for these infants.