Lactation (Encyclopedia of Medicine)
Lactation is the medical term for breastfeeding, a natural method of feeding an infant from birth to the time he or she can eat solid food. Human milk contains the ideal amount of nutrients for the infant, and provides important protection from diseases through the mother's natural defenses.
Early in a woman's pregnancy her milk-producing glands begin to prepare for her baby's arrival, and by the sixth month of pregnancy the breasts are ready to produce milk. Immediately after the baby is born, the placenta is delivered. This causes a hormone in the woman's body (prolactin) to activate the milk-producing glands. By the third to fifth day, the woman's breasts fill with milk.
Then, as the baby continues to suck each day, nursing triggers the continuing production of milk. The baby's sucking stimulates nerve endings in the nipple, which signal the mother's pituitary gland to release oxytocin, a hormone that causes the mammary glands to release milk to the nursing baby. This is called the "let-down reflex." While the baby's sucking is the primary stimulus for this reflex, a baby's cry, thoughts of the baby, or the sound of running water also may trigger the response. Frequent nursing will lead to increased milk production.
Breast milk cannot be duplicated by...
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Lactation (Encyclopedia of Children's Health)
Lactation refers to the formation of milk in the breasts during the period following childbirth. Breastfeeding is the process of the infant obtaining milk by suckling at the breast.
Although breast development begins around puberty, development of mammary function is only completed in pregnancy. During the first half of pregnancy the mammary ducts proliferate and group together to form large lobules. During the second half of pregnancy, secretory activity increases and the alveoli become distended by accumulating colostrum. After 16 weeks of pregnancy, lactation occurs even if the pregnancy does not progress.
The ability of the mammary gland to secrete milk during later pregnancy is called lactogenesis, stage 1. During this time, breast size increases and fat droplets accumulate in the secretory cells. The onset of copious milk secretions after birth is lactogenesis, stage 2, and usually occurs from day two or three to eight days postpartum. During this time, the milk goes through a maturation process to match the infant's needs. Without the hormone prolactin, lactation would not occur. During pregnancy prolactin helps to increase breast mass but does not cause lactation because it is...
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Lactation (Encyclopedia of Nursing & Allied Health)
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
- street drugs (including marijuana, heroin, amphetamines)
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 prolactinhe main hormone involved in the biosynthesis of milkincreases. 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.
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.
Areolahe pigmented, circular area surrounding the nipple of each breast.
Bromocriptine drug used to treat Parkinson's disease that can decrease a woman's milk supply.
Ergotamine drug used to prevent or treat migraine headaches. This can cause vomiting, diarrhea, and convulsions in infants.
Immunoglobulin protein produced by plasma cells; a component of the immune system. Transferred in utero and through breast milk providing passive immunity to the baby.
Lactationecretion of milk from the breasts; the act of breastfeeding.
Latch-onhe 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 drug used to treat manic depression (bipolar disorder) that can be transmitted in breast milk.
Methotrexaten anticancer drug also used to treat arthritis that can suppress an infant's immune system when taken by a nursing mother.
Postpartumefers 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. <<a href="http://www.iblce.org/">http://www.iblce.org/>.
The International Lactation Consultant Association (ILCA). 1500 Sunday Dr., Suite 102, Raleigh, NC 27607. (919) 787-4916. <<a href="http://users.erols.com/ilca/index.html">http://users.erols.com/ilca/index.html>.
Nadine M. Jacobson
Lactation (Encyclopedia of Food & Culture)
LACTATION. Lactation refers to the ability of mammals, warm-blooded, backboned animals, to nourish their young with milk produced by the mammary glands. Many other distinguishing features separate mammals into families that include over four thousand species. The milk of each species is specifically engineered for the growth and developmental needs of that species. In fact studies of the characteristics of the milk can predict the growth rate of both body and brain and the developmental maturity of the offspring at birth. It is also possible to predict the feeding patterns that vary from the whale, which feeds its young every three to four days and has extremely high-fat milk (50 percent), to the human, who initially feeds the infant every two to three hours and has low-protein, low-fat milk (3.4 percent). Some of the world's finest scientists have turned their attention to human lactation and have not only deciphered the micronutrients of human milk but have studied the nutrient needs of the human infant, especially as they pertain to brain development and physical growth. Research also has explained the physiology of human lactation.
Historically, in times of wealth and prosperity, women of higher socioeconomic levels have sought substitute feedings for their infants to "free" themselves of the burden of breast-feeding. Dogma and ritual have developed in different cultures of the world around nursing. It is significant that the Qur'an states that women should nurse their infants for two years. In the Old Testament, the Book of Psalms refers to the value of mother's milk. Pope John Paul II stated that the women of the world should provide their milk for their infants.
When bottle-feeding became more available for the average mother due to the discovery of sterilization, followed by the availability of prepared formulas, the trend toward bottle-feeding increased from 1930 to 1950. Well-educated women led the march to the bottle because they wanted to raise their infants by the book, with scientific information. In the second half of the twentieth century, these same educated women sought a different mode of childbirth in which the mother was prepared and in control. Concomitant with this, well-educated women began looking at breast-feeding as the most appropriate course for their infants.
In 1978 a bipartisan congressional committee charged with the responsibility of designing a health plan for the United States established the year 1990 as the target date for accomplishing several health goals. In addition to statements regarding decreasing hypertension, obesity, and smoking, the committee stated that 75 percent of women should leave the hospital breast-feeding and at least 35 percent should still be breast-feeding at six months. Many of the goals were not accomplished, and in 1990 they were rewritten with a target date of 2000. In 2000 they were rewritten for 2010, aiming at 75 percent of mothers initiating breast-feeding, 50 percent continuing for six months, and 25 percent continuing for a full year. The World Health Organization Code for Infant Feeding was developed in 1981, and the most industrialized countries of the world endorsed this policy, which supported breast-feeding and rejected the promotion of artificial feedings and advertisement of these feedings to the public. The United States did not sign until 1994. The Institute of Medicine, through the Subcommittee on Nutrition during Lactation, confirmed the position that all women, under ordinary circumstances, should breast-feed their infants and further stated that breast-feeding was ideal, even if the mother's diet was not perfect. The American Academy of Pediatrics, joined by the American College of Obstetrics and Gynecology, stated in 1997 that infants should be exclusively breast-fed for five to six months. They further stated that breast-feeding should continue as weaning foods are added through the first year of life and then for as long thereafter as the mother and the infant choose
Significance of Breast-Feeding to Health
Why have all of these important groups spoken out so strongly in favor of breast-feeding? The knowledge that human milk is for the human infant has been accepted for centuries. In the late twentieth century, however, considerable scientific investigation established unequivocally that breast-feeding is associated with a reduced incidence of infection in the infant, including reduced incidences of gastrointestinal, upper and lower respiratory, ear, and urinary tract infections. Immunologic data have shown reduced incidences of childhood-onset cancers, especially lymphoma and acute lymphocytic leukemia. Crohn's disease, celiac disease, and childhood-onset diabetes also are reduced when infants are breast-fed for at least four months. Probably the most dramatic information published in multiple articles is the relationship between breast-feeding and infant development. A study by Niles Newton compared the developmental progress of breast-fed and bottle-fed three-year-olds. Alan Lucas, Ruth Morley, T. J. Cole, and others reported a multisite study that compared premature babies given their mother's milk by feeding tube with infants given premature-infant formula. The group studied them at eighteen months and followed them until seven and a half to eight years of age. The study showed an 8.5-point difference when the data were adjusted for socioeconomic status and education of the mother. The eighteen-year study by L. John Horwood and David M. Fergusson in New Zealand showed a measurable difference at eighteen years of age in school outcomes and behaviors related to whether or not the children were breast-fed in infancy. Although these studies have been criticized for design flaws, many scientists accept their findings. These results are in addition to the compelling psychologic benefit to the mother and the infant in their relationship during breast-feeding.
Facilitating the Decision to Breast-Feed
A mother needs an opportunity to make an informed decision about how to feed her infant. If a mother comes to pregnancy without any information on this process, it is the health care provider's responsibility to see that she is well informed about the benefits of breast-feeding for her baby, for herself, and for society so she can make a decision that will be optimal.
The economic benefit of breast-feeding. A simple calculation of the cost of buying formula does not reflect completely the monetary benefits of breast-feeding. It costs between $60 and $80 a month to purchase infant formula, $700 to $1,000 for the first year of life. Careful studies in controlled populations, such as in health maintenance organizations, have demonstrated in multiple reports that infants who are not breast-fed have an increased number of illnesses, visits to the doctor, prescription medications, and hospitalizations compared with their breast-fed counterparts. The estimate per infant of the health care costs not to breast-feed is between $600 and $1,000 per year. This estimate does not include the reduction in the onset of chronic illnesses that may last a lifetime, such as diabetes, Crohn's disease, and allergies.
Benefits to the mother. The benefits of breast-feeding to the mother are often ignored. Women who breast-feed return to their prepregnant, physiologic states more rapidly. The uterus involutes, the postpartum blood loss is reduced, and the woman returns to her physiologic weight as well. Among other possible benefits are reduced incidences of long-term obesity, breast cancer, ovarian cancer, and most remarkably long-term osteoporosis. Although breast-feeding is not a contraceptive, it significantly affects the fertility in the childbearing years by suppressing ovulation.
Establishing lactation. Critical information about the mother's potential for a good milk supply is obtained during pregnancy. When the obstetrician does the early examination of the breasts in the first trimester, the breasts should be evaluated with respect to their potential for producing milk. Unusually small, unusually large, asym-metric, or tubular-shaped breasts may pose a problem. Prior surgery of the breast should be discussed. Lumpectomies and augmentation mammoplasty are not contraindications. Reduction mammoplasty, however, may pose a problem if the integrity of the ducts was interrupted. The obstetrician should also evaluate the breasts' responses to the hormones of pregnancy, the degree of increase in size of the breasts, and changes in the areola and nipple. The obstetrician should discuss with the mother her intentions to breast-feed and address any questions she may have. The mother should be encouraged to attend breast-feeding preparation classes, which are commonly available at hospitals with maternity services and at local mothers' groups.
The breast prepares for lactation during pregnancy by enhancing the ductal system and developing lacteal cells that will produce the milk. From about sixteen weeks in gestation on, the breast is capable of making milk if the fetus is delivered. During pregnancy the placenta produces a prolactin-inhibiting hormone (PIH) that blocks the breast from responding to the abundant prolactin of pregnancy. Once the placenta is delivered, the PIH drops, and the breast responds to the hormones oxytocin and prolactin.
The key response of the breast following delivery is called the ejection or letdown reflex, prompted by two major hormones, oxytocin and prolactin. Oxytocin causes myoepithelial cells to contract. Thus when the baby stimulates the breast by suckling, a message is sent via the peripheral nervous system to the mother's brain and pituitary to release oxytocin, which in turn causes the myoepithelial cells that surround the alveoli and the ductal system to contract, ejecting the milk from the ducts. Suckling at the breast also stimulates the release of prolactin, the hormone that stimulates the lacteal cells to produce milk. Prolactin is not released unless the breast is stimulated. Oxytocin, however, may be released when the mother sees her baby or hears her baby cry or as a result of other stimulating sensory pathways.
It is recommended that the infant be put to breast as soon after delivery as is possible. The infant has been sucking and swallowing in utero, consuming considerable amniotic fluid, from about fourteen weeks gestation on, so he or she is ready to begin breast-feeding.
To put the infant to breast, the infant is held with his or her abdomen against the mother's and the infant looking directly at the breast. The mother supports the breast with her hand, keeping her fingers behind the areola and gently compressing it. The mother strokes the center of the infant's lower lip with the nipple. This stimulates the infant to open his or her mouth, extend his or her tongue, and draw the nipple and the areola into his or her mouth. The baby's tongue compresses the elongated nipple and areola against his or her hard palate. The peristaltic motion of the tongue stimulates the letdown reflex, and milk is released and swallowed. Infants should be fed when hungry, which is eight to twelve times a day initially. No other food or drink is necessary during exclusive breast-feeding for up to six months.
See also Baby Food; Dairy Products; Milk, Human.
American Academy of Pediatrics Work Group on Breastfeeding. "Breastfeeding and the Use of Human Milk." Pediatrics 100 (1997): 1035.
Ball, Thomas M., and Anne L. Wright. "Health Care Costs of Formula-Feeding in the First Year of Life." Pediatrics 103 (1999): 870.
Biancuzzo, Marie. Breastfeeding the Newborn: Clinical Strategies for Nurses. St. Louis, Mo.: Mosby, 1999.
Horwood, L. John, and David M. Fergusson. "Breastfeeding and Later Cognitive and Academic Outcomes." Pediatrics 101 (1998): 39.
Huggins, Kathleen. The Nursing Mother's Companion. 4th ed. Boston: Harvard Common Press, 1999.
Institute of Medicine, Subcommittee on Nutrition during Lactation. Nutrition during Lactation. Washington, D.C.: National Academy Press, 1991.
Lawrence, Ruth A., and Robert M. Lawrence. Breastfeeding: A Guide for the Medical Profession. 5th ed. St. Louis, Mo.: Mosby, 1999.
Lucas, Alan, Ruth Morley, T. J. Cole, et al. "Breast Milk and Subsequent Intelligence Quotient in Children Born Preterm." Lancet 339 (1992): 261.
Newton, Niles. "Psychological Differences between Breast and Bottle Feeding." American Journal of Clinical Nutrition 24 (1971): 993.
United States Department of Health and Human Services. Healthy People 2010. Conference ed. in 2 vols. Washington, D.C.: U.S. Department of Health and Human Services, 2000.
Ruth A. Lawrence