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Lactation is the medical term used for breastfeeding. It also specifically refers to the synthesis and secretion of milk.


Breastfeeding provides a baby with nutrition in the form of breast milk. Not only does breast milk contain all the nutrients needed by a rapidly developing newborn, but it also contains antibodies that provide the baby with additional protection from common early childhood diseases.


Most common illnesses can not be transmitted via breast milk. However, some viruses , including HIV (the virus that causes AIDS ) can be passed in breast milk; for this reason, women who are HIV-positive should not breastfeed.

Many medications have not been tested in nursing women, so it is not known if these drugs can affect a breast-fed child. A nursing woman should always check with her doctor before taking any medications, including over-the-counter drugs.

These drugs are not safe to take while nursing:

  • radioactive drugs for some diagnostic tests
  • chemotherapy drugs for cancer
  • bromocriptine
  • ergotamine
  • lithium
  • methotrexate
  • street drugs (including marijuana , heroin, amphetamines)
  • tobacco


Early in a woman's pregnancy her milk-producing glands, called mammary glands, begin to prepare for the baby's arrival and by the sixteenth week of pregnancy the breasts are ready to produce milk. Shortly after the baby is born, the expulsion of the placenta triggers hormone shifts in the woman's body to activate lactation. The levels of the hormones estrogen and progesterone fall abruptly while the level of the hormone prolactin—the main hormone involved in the biosynthesis of milk— increases. The anterior pituitary gland secretes prolactin during lactation in very large quantities so that by 36 to 96 hours postpartum the woman's milk volume has dramatically increased. Subsequently, the volume of milk the mother produces levels off and the removal of milk becomes the predominant factor in regulating milk production.

Another hormone called oxytocin controls the release of milk from the breasts. The baby's sucking stimulates nerve endings in the nipple, which signal the mother's pituitary gland to release the oxytocin. This is called the "let-down reflex." While the baby's sucking is the primary stimulus for the reflex, a baby's cry, thoughts of the baby, or the sound of running water also may trigger the response.

Breast milk cannot be duplicated by artificial milk, although both contain protein, fat, and carbohydrates . Breast milk changes to meet the specific needs of a baby.

In particular, the mother produces milk called colostrum at the end of pregnancy and in the initial postpartum period. Colostrum is called "first milk" and is thicker than mature milk. It is yellowish in color and is rich in proteins , many of which are immunoglobulins that can protect the child against illness and allergies . Immunoglobuoins are part of the body's natural defense system against infections and other agents that can cause disease. Breast milk also helps a baby's own immune system mature faster. As a result, breast-fed babies have fewer ear infections, bouts of diarrhea , rashes, allergies, and other medical problems than bottle-fed babies do.

There are many other benefits to breast milk. Because it is easily digested, babies do not get constipated. Breast-fed babies have fewer speech impediments due to good cheekbone development and jaw alignment.

Breastfeeding is also good for the mother. It releases hormones that stimulate the uterus to contract, helping the uterus to return to normal size after delivery and reducing the risk of bleeding. The act of producing milk burns calories, which helps the mother to lose excess weight gained during pregnancy. Breastfeeding also may be related to a lower risk of breast cancer , ovarian cancer, and cervical cancer.

Breast milk is free, and saves money by eliminating the need to buy artificial milk (formula), bottles, and nipples. Because breast-fed babies overall have fewer illnesses, their health care costs may be lower.

Breastfeeding should begin as soon as possible after birth and should continue every two to three hours. However, all babies are different; some need to nurse very frequently at first, while others can go much longer between feedings. A baby should be fed at least eight to 12 times in 24 hours. Because breast milk is easily digested, a baby may be hungry again as soon as one and one-half hours after the last meal. Frequent nursing will also help in increasing milk production.

Some babies have no trouble breastfeeding, while others may need some assistance. Once the baby begins to suck, the mother should make sure that most of the areola is in the baby's mouth. Proper latching-on will help stimulate milk flow and will prevent nipple soreness.

Breastfeeding mothers should offer the baby both breasts at each feeding. Breastfeeding takes about 15-20 minutes on each side. After stopping the feeding on one side, the mother should burp the baby before beginning the feeding on the other breast. The next feeding should begin with the breast that the baby nursed on last.

Mothers can tell if the baby is getting enough milk by checking diapers; a baby who is wetting between four to six disposable diapers (six to eight cloth) and who has three or four bowel movements in 24 hours is getting enough milk.


Loose, front-opening clothes and a good nursing bra are recommended. Mothers should find a comfortable chair with lots of pillows, supporting the arm and back, to nurse in. Feet should rest on a low footstool with knees raised slightly. The baby should be level with the breast. The new mother may have to experiment with different ways of holding the baby before finding one that is comfortable for both the mother and baby.


Breastfeeding problems

New mothers may experience breastfeeding problems, including:

  • Engorged breasts. Breasts that are too full can prevent the baby from sucking. Expressing milk manually or with a breast pump can help, as can warm showers and compresses.
  • Sore nipples. In the early weeks nipples may become sore and even cracked. Treatments include changing the position that the baby nurses in, ensuring that the baby has latched on to most of the areola, and using lanolin-based lotion on the nipples. Nipple shields are sometimes effective as a short-term remedy but their use may reduce milk supply, further irritate the breast, and change the baby's sucking pattern.
  • Inverted nipples: A mother with inverted nipples may still breastfeed in most instances. The baby should be enticed to open the mouth widely before latching on. The mother can use various techniques to evert the nipple such as wearing a breast shell between feedings, rolling the nipple, pulling the nipple out, and applying a breast pump on the breast for a few seconds before starting the breastfeeding session.
  • Infection . Soreness and inflammation on the breast surface or a fever in the mother, may be an indication of a breast infection called mastitis . Antibiotics and continued nursing on the affected side may solve the problem.

Suggestions for breastfeeding women who work outside the home

stay at home as long as possible, and work part-time, if possible.

try taking a few hours away from the baby to anticipate problems.

have an extra set of towels, an extra bra, and a change of clothes at the work site.

take a quart of liquid to work and remember to drink it frequently.

when choosing a pump, consider portability as well as cost and comfort.

practice with a pump ahead of time to get used to it and so that the milk will let-down quickly.

if working full-time and manual expression or a manual pump is objectionable or does not work well, rent a dual hook-up electric pump to keep at work.

find a place at work to feel comfortable and have some privacy while pumping, and have a backup place in mind as well.

if the baby will be in day care, be certain the day care provider is supportive of breastfeeding.

arrange to nurse the baby during the day if possible.

arrive early at the day care provider's site to nurse the baby right before going to work to help the baby settle down and allow time for talking with the provider.

source: wheeler, l. nurse-midwifery handbook: a practical guide to prenatal and postpartum care. philadelphia: lippincott-raven pub., 1997.


There are no rules about when to stop breastfeeding. A baby needs breast milk or artificial milk for at least the first year of life. As long as a baby eats age-appropriate solid food, the mother may nurse for several years.

Health care team roles

Several members of the health care team, including obstetricians, nurses, midwives, and lactation consultants, are equipped to provide guidance and support to mothers who wish to breastfeed their babies. By meeting specific eligibility requirements and passing an independent examination, lactation consultants may be certified by the International Board of Lactation Consultants. Such certification demonstrates that these consultants possess the necessary skills, knowledge, and attitudes to provide quality breastfeeding assistance. It is important for new mothers to understand that breastfeeding is something that mothers and babies must learn to do together. The development of a satisfying breastfeeding relationship requires patience on the mother's part and the mother may benefit from the support and guidance of a lactation consultant or other qualified member of her health care team.


Areola —The pigmented, circular area surrounding the nipple of each breast.

Bromocriptine —A drug used to treat Parkinson's disease that can decrease a woman's milk supply.

Ergotamine —A drug used to prevent or treat migraine headaches. This can cause vomiting, diarrhea, and convulsions in infants.

Immunoglobulin —A protein produced by plasma cells; a component of the immune system. Transferred in utero and through breast milk providing passive immunity to the baby.

Lactation —Secretion of milk from the breasts; the act of breastfeeding.

Latch-on —The process whereby the baby opens the mouth widely and first exerts negative pressure on the mother's nipple and then positive pressure. Good latch-on will result in adequate transfer of milk into the baby's mouth and prevent sore nipples from occurring.

Lithium —A drug used to treat manic depression (bipolar disorder) that can be transmitted in breast milk.

Methotrexate —An anticancer drug also used to treat arthritis that can suppress an infant's immune system when taken by a nursing mother.

Postpartum —Refers to the six-week period after childbirth.



Biancuzzo, Marie. Breastfeeding the Newborn. St. Louis: Mosby, 1999.

Cunningham, F. Gary, et al. Williams Obstetrics. 20th ed. Stamford, CT: Appleton & Lange, 1997.

Riordan, Jan, and Kathleen G. Auerbach. Breastfeeding and Human Lactation. 2nd ed. Boston: Jones & Bartlett, 1999.


The International Board of Lactation Consultant Examiners (IBLCE). 7309 Arlington Blvd., Suite 300, Falls Church, VA 22042-3215. (703) 560-7330. <>.

The International Lactation Consultant Association (ILCA). 1500 Sunday Dr., Suite 102, Raleigh, NC 27607. (919) 787-4916. <>.

Nadine M. Jacobson