Composition of breast milk
Soon after delivery small quantities of thick, yellowish, viscous liquid called colostrum is secreted which is rich in antibodies and Vitamin A. This should be given to the baby and not discarded.
After a few days of lactation the mother secretes larger amounts of less viscous and whitish milk known as 'mature milk' which is more or less a complete food nutritionally. A healthy mother secretes 850ml of milk daily for which her nutritional needs are increased enormously.
gives the composition of mother's milk.
Composition of mother's milk
Nutrient Quantity / 100 ml
Energy 65 k.cal
Vitamin A (Retinol) 137 I.U.
Thiamine 0.02 µg
Riboflavin 0.02 µg
Vitamin C 3mg
Source : Gopalan C., Ramasastri B.V. and Balasubramanian S.C., (2000). Nutritive value of Indian Foods,
NIN, ICMR, Hyderabad, India.
The process of milk production and secretion occurs in two distinct stages.
i. Prolactin reflex
When the baby sucks the breast, nerve impulses are passed up the spinal cord to the hypothalamus which stimulates anterior pituitary leading to the secretion of prolactin. Prolactin is carried via the blood stream to the alveoli in the breasts where it stimulates milk production.
ii. Let down reflex
When the baby sucks, nerve impulses are passed to the posterior pituitary producing another hormone, oxytocin. Oxytocin contracts the muscle cells around the alveoli, squeezing out milk and propelling it down to the nipples.
The let down reflex is highly sensitive to emotional and psychological disturbances as well as physical contact. The mother's emotions, the baby's cry or even the baby's thought might initiate this reflex. On the other hand, anxiety, fear and tension may inhibit this reflex. Hence the mother should be comfortable and relaxed while feeding the baby.
These two reflexes operate simultaneously and release milk. Fig. represents the process of stimulation of milk production.
As long as pituitary produces these lactogenic hormones, it cannot produce sufficient Follicle Stimulating Hormone (FSH) and Leutenizing Hormone (LH) which bring about ovulation. Thus lactation brings about natural contraception.