Breast milk

Alternative names:

human milk; milk - human

Definition:

The milk produced by human (female) breasts.

Functions:

Breast milk is the perfect source of nutrition for infants. Breast milk contains appropriate amounts of carbohydrate, protein, and fat. It also provides digestive enzymes, minerals, vitamins, and hormones that all infants require. Breast milk also contains valuable antibodies from the mother that can help the baby resist infections. Breast milk is not a rich source of iron but healthy infants have adequate iron stores to last until 8 months of age. Iron-rich foods can be started at this age (see diet for age). Your pediatrician or dietitian may recommend Fluoride supplementation in communities where water is not fluoridated (areas with less than 0.25 p.p.m. Fluoride).

Cow's milk by itself is inappropriate for infants less than 1 year old. The infant or can develop an allergy to dairy products if given cow's milk to early in life. Although cow's milk contains most of the same components as breast milk, these components are not in the same amounts. Cow's milk also lacks the immune factors, called antibodies, that help protect infants until their own immune system fully develops. Commercially prepared formulas may be based on non fat cow's milk, whey protein, or soy protein. In order to provide a balanced diet for an infant, formulas must be fortified with carbohydrates, fats, minerals, and vitamins. The antibodies found in breast milk, however, can never be added to formulas.

BREAST MILK PRODUCTION
Milk is produced in small sac-like glands (alveoli) in the breast. These sacs develop after specific hormonal (estrogen, progesterone, pituitary prolactin, and placental lactogen) stimulation that begins during four to six months (second trimester) of pregnancy.

The human breast does not store a large volume of milk as cow's do. Most of the milk your baby ingests during breast feeding is during nursing. Suckling stimulates the release of a hormone (prolactin) which, stimulates milk production and the release of another hormone (oxytocin). Oxytocin, in turn, stimulates contraction (or the "let-down reflex") of the milk glands. The milk is squeezed out of the milk gland, into the milk ducts, and into the nipple.

At the beginning of the feeding, the milk is bluish and contains lactose and proteins, but little fat; it is called foremilk. The end of the feeding produces hindmillk. The hindmilk contains more fat, the main source of energy for your baby. If breast milk is allowed to sit for half-an-hour after being expressed, the "cream" separates and settles on top of the watery part. This is because human milk isn't homogenized, the process that makes the water and fat portion in milk stay in "one layer."

MILK EJECTION REFLEX
Some mothers feel a tingling sensation as the milk begins to eject from the breast due to the let-down reflex. The best way to monitor whether this milk-ejection reflex has begun is by watching the sucking and breathing patterns of your baby. At the start of a feeding, you will notice a pattern such as: suck, suck, suck, swallow, suck, suck, suck, swallow. This pattern may last up to 30 seconds but could be longer. As the milk ejection reflex takes over, the pattern may be described as gulping: one swallow, one deep breath, one swallow, one deep breath. This pattern may last for 2 to 4 minutes. Your baby may want to nurse longer (maybe 15 or 20 minutes) on this breast in order to get more fat from the hind milk and/or because to fill a need for sucking. Rather than watching the clock to let him nurse "10 minutes on each side," you may want to allow your baby to break off the first breast at his own timing before switching to the other breast.