Breastfeeding is the practice of feeding an infant milk through the mother's breast. According to La Leche League International (LLLI), human milk is "a living fluid that protects babies from disease and actively contributes to the development of every system in baby's body." Breastfeeding stimulates the immune systems of babies and helps to protect against diarrhea and infection.

(Fig 2.13.)
When an infant is properly latched onto the breast, the baby's nose touches (or nearly touches) the breast. He or she takes the entire areola into the mouth, facilitating the intake of milk far back into the throat.


The purpose of breastfeeding is to provide healthy nutrition for a newborn infant at low cost.


The mother's body prepares for breastfeeding while she is pregnant. The fatty tissue of the breast is replaced by glandular tissue that is necessary to produce milk. When baby suckles the breast the hormone oxytocin is released. This causes the muscle cells of the breast to squeeze milk from the milk ducts to the nipple.


Since the advent of humans, mothers have breastfed their babies. During ancient times mothers breastfed their babies for 12-18 months or until the mother's menstrual cycle returned.

For thousands of years breastfeeding was the only source of nutrition for the first part of a baby's life. Before the invention of infant formula, few alternatives were available. If a mother could not breastfeed, a wet nurse was found or the baby was fed animal milk or "pap," a mixture of flour, rice, and water. In the early 1900s, most babies in America were still breastfed, and over half of them were breastfed for one year or longer. However, as more women entered the workforce and supplemental methods of feeding were introduced, breastfeeding rates in America decreased. According to a survey from Ross Labs, by 1971 only 24.7% of American babies were breastfed at birth, and of these babies, only 5.4% of them were still breastfed at 6 months. Beginning in the mid 1980s, breastfeeding began to be strongly encouraged in the United States. Breast milk is today considered the best nutrition for an infant, although infants can still grow and thrive on infant formula.

Composition of breast milk

Breast milk is the perfect food for an infant. It contains all the nutrients a baby needs to grow and stay healthy, such as:

  • Fats. Breastmilk contains omega-3 fatty acids essential for the growth and development of the brain and nerve tissue. The amount of fat a baby receives depends on the length of the feeding. The milk at the beginning of the feeding is called the foremilk. It is the low-fat milk. The hindmilk that comes at the end of the feeding contains higher concentrations of fat. Therefore, the longer the baby nurses the higher the fat content.
  • Proteins. The whey proteins found in breast milk are easier to digest than formula. Taurine, an amino acid that is important in the development of brain tissue, is found in breast milk but not in cow's milk.
  • Sugars. Breast milk contains lactose, a milk sugar that provides energy. Breast milk contains 20%-30% more lactose than cow's milk.
  • Vitamins and minerals. Breast milk provides the most balanced source of vitamins and minerals for an infant.
  • Immune system boosters. White blood cells and immunoglobulins are responsible for fighting and destroying infection.

The content of breast milk varies from feeding to feeding, at different times of day, and as the baby grows.

Benefits for baby

There are many benefits for the breastfeeding baby, including:

  • Increased immunity. Breast milk contains antibodies that are relayed by the mother and help to protect the baby from bacteria and viruses. These immunoboosters are not found in formula.
  • Lower incidence of ear infections and respiratory infections.
  • Potentially higher intelligence. Several studies have found higher levels of brain-boosting Docosahexaenoic acid (DHA) in the blood levels of breastfed babies than in formula-fed babies.
  • Improved digestion and less constipation.
  • Decreased risk of diarrhea, pneumonia, urinary tract infections, and certain types of spinal meningitis.
  • Decrease in food allergies and eczema.
  • More normal weight gain. Breastfed babies are less likely to be overweight than formula-fed babies.
  • Reduced risk of type 1 (juvenile) and type 2 (adult onset) diabetes, celiac disease, cancer, rheumatoid arthritis, multiple sclerosis, liver disease, and acute appendicitis.
  • Lower risk of sudden infant death syndrome (SIDS).
  • Reduced risk of breast cancer (in daughters who have been nursed).
  • Better development of jaw and facial structure
  • Strong bonding between mother and child.

Benefits for mother

Breastfeeding women also enjoy many benefits:

  • Reduced risk of breast, ovarian, and uterine cancers.
  • Natural contraceptive. Many women who breastfeed exclusively for six months experience a delay of fertility.
  • Faster postpartum recovery. Breastfeeding uses up extra calories so it is easier for moms to lose their pregnancy weight. Nursing also helps the uterus shrink back to its normal size faster.
  • Relaxation. When a mother is breastfeeding her body produces oxytocin, a hormone that induces a calm, content feeling.
  • Protection from osteoporosis.
  • Savings in time and money. Breast milk is cheaper than formula and the mother does not have to spend time preparing bottles.
  • Better stewardship of the environment, as there are no bottles to wash or cans to dispose of.

Maternal nutrition

The ideal diet of a breastfeeding woman is comprised of healthy and nutritious foods from the five basic food groups. Foods high in carbohydrate such as pastas, grains, and fruits should make up about half of the daily food intake. Healthy fats, such as fatty fish and avocados, should be 30%, and proteins should equal 15%-20%. Breastfeeding women should make sure to eat foods that contain a lot of calcium, such as dairy products, broccoli, and beans, and make sure they eat plenty of iron-rich foods like lean red meat, fish, and poultry.

In order to compensate for the energy they expend breastfeeding their babies, breastfeeding women should add 300-500 extra nutritious calories to their diet each day and drink extra fluids. Breastfeeding mothers should also continue to take a prenatal vitamin.


Almost every substance that a breastfeeding mother puts into her body has the potential to pass to her baby through her breast milk. This includes food, medicine, alcohol, and cigarettes.

  • Foods: Foods such as dairy products, caffeine, grains and nuts, gassy foods, and spicy foods may cause the baby to fuss if the food upsets the baby's stomach. If this occurs, the mother should eliminate the suspect food from her diet for 10-14 days to see if the trouble stops.
  • Medications: Any medication taken while breastfeeding should be approved by a doctor.
  • Birth control pills: The high estrogen type of birth control pills may decrease a breastfeeding mother's milk supply and are not recommended. A progestinonly pill such as the "mini-pill" is the least likely to cause milk supply issues.
  • Alcohol: Infants have a hard time detoxifying from the alcohol that passes through their mother's breast milk to them. It is recommended to limit alcohol consumption while breastfeeding.
  • Cigarettes: Cigarettes contain toxins that can pass through to the baby and are not recommended for breastfeeding women.

When breastfeeding is not an option

Although breastfeeding is the optimal way to feed an infant, sometimes it is not possible or feasible. A small percentage of women have conditions that prevent breast milk production, such as insufficient development of milk production glands, and cannot breastfeed. Women with HIV infection are advised against breastfeeding, as the virus may be passed to their babies. Women who are newly diagnosed with infectious tuberculosis should not breastfeed unless they are on medication. Other health conditions may require that the woman take medication that prevents them from breastfeeding. Babies with galactosemia, a rare genetic disorder that prevents them from metabolizing the sugar in breast milk, cannot breastfeed.