Lactation
பாலூட்டுதல்
Lactation is not merely milk production; it is the final endocrine milestone of pregnancy. Do not confuse it with the mere ejection of milk. It is a complex hormonal cascade triggered by the withdrawal of progesterone and the surge of prolactin.
The idea
Mammary glands undergo differentiation during pregnancy, culminating in lactation towards the end of gestation. The initial yellowish fluid secreted during the first few days of lactation is colostrum. It contains several antibodies, essentially IgA, which are critical for developing resistance in the newborn. This passive immunity is non-negotiable for neonatal survival.
Why it matters
It provides the newborn with essential nutrition and passive immunity to develop resistance against infections.
NEET lens
NEET focuses on the composition of colostrum and the role of antibodies. Remember: Colostrum contains IgA. Do not confuse it with IgG, which crosses the placenta. Expect questions linking lactation to the hormonal control of the mammary glands.
Clinical significance
Failure of lactation often stems from endocrine imbalances, specifically prolactin deficiency or pituitary dysfunction. Without colostrum, the neonate loses the primary source of passive immunity, significantly increasing susceptibility to gastrointestinal and respiratory infections. Breastfeeding is the clinical gold standard for neonatal health.
Introduction
Lactation is the production and secretion of milk by the mammary glands, initiated after childbirth under the influence of prolactin (milk synthesis) and oxytocin (milk ejection/let-down reflex), providing the newborn with complete nutrition and passive immunity.
Core concept
Hormones: Prolactin (anterior pituitary): stimulates milk synthesis by alveolar cells of mammary glands. Rises during pregnancy, suppressed by high estrogen/progesterone. Falls in estrogen/progesterone → prolactin action → milk synthesis begins after delivery. Oxytocin (posterior pituitary): released by suckling reflex → myoepithelial cells contract → milk ejection (let-down). Colostrum: milk produced in first few days. Yellow, thick. Rich in IgA antibodies (passive immunity), protein, vitamin A, leukocytes. Less fat than mature milk. Then mature milk: white, balanced nutrients (lactose, protein, fat, vitamins, minerals, growth factors). Duration: WHO recommends exclusive breastfeeding for 6 months. Contraceptive effect: prolactin inhibits GnRH → suppresses ovulation (lactational amenorrhoea — natural spacing).
Go deeper
Milk ejection reflex: infant suckling → sensory neurons → hypothalamus → oxytocin release → myoepithelial cells in alveoli contract → milk propelled into ducts → let-down. Emotional cues (baby's cry) can also trigger oxytocin release. Stress (high cortisol/adrenaline) inhibits oxytocin → impairs let-down (breastfeeding difficulties in stressed mothers).
From Class 10
After childbirth, the mother's body produces milk to feed the newborn. This milk production by the mammary glands is called lactation.