Breastfeeding is the feeding of an infant or young child with breast milk directly from female human breasts (i.e., via lactation) rather than from a baby bottle or other container. Babies have a sucking reflex that enables them to suck and swallow milk. It is recommended that mothers breastfeed for six months or more, without the addition of infant formula or solid food. After the addition of solid food, mothers are advised to continue breast-feeding up to a year, and can continue until two years.
Human breast milk is the healthiest form of milk for babies. There are few exceptions, such as when the mother is taking certain drugs or is infected with human T-lymphotropic virus, HIV, or has active untreated tuberculosis. Breastfeeding promotes health and helps to prevent disease. Artificial feeding is associated with more deaths from diarrhea in infants in both developing and developed countries. Experts agree that breastfeeding is beneficial, but have conflicting views about how long breastfeeding remains beneficial. They also express concerns about the risks of using artificial formulas.
The World Health Organization (WHO) and the American Academy of Pediatrics (AAP) emphasize the value of breastfeeding for mothers as well as children. Both recommend exclusive breastfeeding for the first six months of life and then supplemented breastfeeding for at least one year and up to two years or more. While recognizing the superiority of breastfeeding, regulating authorities also work to minimize the risks of artificial feeding.
During breastfeeding, antibodies pass to the baby. This is one of the most important features of colostrum, the breast milk created for newborns. Breast milk contains several anti-infective factors such as bile salt stimulated lipase (protecting against amoebic infections), lactoferrin (which binds to iron and inhibits the growth of intestinal bacteria) and immunoglobulin A protecting against microorganisms.
Among the studies showing that breastfed infants have a lower risk of infection than non-breastfed infants are:
- In a 1993 University of Texas Medical Branch study, a longer period of breastfeeding was associated with a shorter duration of some middle ear infections (otitis media with effusion) in the first two years of life.
- A 1995 study of 87 infants found that breastfed babies had half the incidence of diarrheal illness, 19% fewer cases of any otitis media infection, and 80% fewer prolonged cases of otitis media than formula fed babies in the first twelve months of life.
- Breastfeeding appeared to reduce symptoms of upper respiratory tract infections in premature infants up to seven months after release from hospital in a 2002 study of 39 infants.
- A 2004 case-control study found that breastfeeding reduced the risk of acquiring urinary tract infections in infants up to seven months of age, with the protection strongest immediately after birth.
- The 2007 review for AHRQ found that breastfeeding reduced the risk of acute otitis media, non-specific gastroenteritis, and severe lower respiratory tract infections.
Studies have examined whether breastfeeding in infants is associated with higher intelligence later in life. Many have found a connection:
- Horwood, Darlow and Mogridge (2001) tested the intelligence quotient (IQ) scores of 280 low birthweight children at seven or eight years of age. Those who were breastfed for more than eight months had verbal IQ scores 6 points higher (which was significantly higher) than comparable children breastfed for less time. They concluded "These findings add to a growing body of evidence to suggest that breast milk feeding may have small long term benefits for child cognitive development."
- A 2005 study using data on 2,734 sibling pairs from the National Longitudinal Study of Adolescent Health "provide[d] persuasive evidence of a causal connection between breastfeeding and intelligence." The same data "also suggests that nonexperimental studies of breastfeeding overstate some of [breastfeeding's] other long-term benefits, even if controls are included for race, ethnicity, income, and education."
- The 2007 review for the WHO "suggests that breastfeeding is associated with increased cognitive development in childhood." The review also states that "The issue remains of whether the association is related to the properties of breastmilk itself, or whether breastfeeding enhances the bonding between mother and child, and thus contributes to intellectual development."
- * Two initial cohort studies published in 2007 suggest babies with a specific version of the FADS2 gene demonstrated an IQ averaging 7 points higher if breastfed, compared with babies with a less common version of the gene who showed no improvement when breastfed. FADS2 affects the metabolism of polyunsaturated fatty acids found in human breast milk, such as docosahexaenoic acid and arachidonic acid, which are known to be linked to early brain development. The researchers were quoted as saying "Our findings support the idea that the nutritional content of breast milk accounts for the differences seen in human IQ. But it's not a simple all-or-none connection: it depends to some extent on the genetic makeup of each infant." The researchers wrote "further investigation to replicate and explain this specific gene–environment interaction is warranted."
- In "the largest randomized trial ever conducted in the area of human lactation," between 1996 and 1997 maternity hospitals and polyclinics in Belarus were randomized to receive or not receive breastfeeding promotion modeled on the Baby Friendly Hospital Initiative. Of 13,889 infants born at these hospitals and polyclinics and followed up in 2002-2005, those who had been born in hospitals and polyclinics receiving breastfeeding promotion had IQs that were 2.9-7.5 points higher (which was significantly higher). Since (among other reasons) a randomized trial should control for maternal IQ, the authors concluded in a 2008 paper that the data "provide strong evidence that prolonged and exclusive breastfeeding improves children's cognitive development."
However, some have not found a connection:
- In 2006, Der and colleagues, having performed a prospective cohort study, sibling pairs analysis, and meta-analysis, concluded that "Breast feeding has little or no effect on intelligence in children." The researchers found that "Most of the observed association between breast feeding and cognitive development is the result of confounding by maternal intelligence."
- The 2007 review for the AHRQ found "no relationship between breastfeeding in term infants and cognitive performance."
Infants exclusively breastfed have less chance of developing diabetes mellitus type 1 than peers with a shorter duration of breastfeeding and an earlier exposure to cow milk and solid foods. Breastfeeding also appears to protect against diabetes mellitus type 2, at least in part due to its effects on the child's weight.
Less childhood obesity
Breastfeeding appears to reduce the risk of extreme obesity in children aged 39 to 42 months. The protective effect of breastfeeding against obesity is consistent, though small, across many studies, and appears to increase with the duration of breastfeeding. A study has also shown that infants who are bottle-fed in early infancy are more likely to empty the bottle or cup in late infancy than those who are breastfed. "Bottle-feeding, regardless of the type of milk, is distinct from feeding at the breast in its effect on infants' self-regulation of milk intake." According to the study, this may be due to one of three possible factors, including that when bottle feeding, parents may encourage an infant to finish the contents of the bottle whereas when breastfeeding, an infant naturally developes self-regulation of milk intake.
Less tendency to develop allergic diseases (atopy)
In children who are at risk for developing allergic diseases (defined as at least one parent or sibling having atopy), atopic syndrome can be prevented or delayed through exclusive breastfeeding for four months, though these benefits may not be present after four months of age. However, the key factor may be the age at which non-breastmilk is introduced rather than duration of breastfeeding. Atopic dermatitis, the most common form of eczema, can be reduced through exclusive breastfeeding beyond 12 weeks in individuals with a family history of atopy, but when breastfeeding beyond 12 weeks is combined with other foods incidents of eczema rise irrespective of family history.
Less necrotizing enterocolitis in premature infants
Necrotizing enterocolitis (NEC) is an acute inflammatory disease in the intestines of infants. Necrosis or death of intestinal tissue may follow. It is mainly found in premature births. In one study of 926 preterm infants, NEC developed in 51 infants (5.5%). The death rate from necrotizing enterocolitis was 26%. NEC was found to be six to ten times more common in infants fed formula exclusively, and three times more common in infants fed a mixture of breast milk and formula, compared with exclusive breastfeeding. In infants born at more than 30 weeks, NEC was twenty times more common in infants fed exclusively on formula. A 2007 meta-analysis of four randomized controlled trials found "a marginally statistically significant association" between breastfeeding and a reduction in the risk of NEC.
Other long term health effects
In one study, breastfeeding did not appear to offer protection against allergies. However, another study showed breastfeeding to have lowered the risk of asthma, protect against allergies, and provide improved protection for babies against respiratory and intestinal infections.
A review of the association between breastfeeding and celiac disease (CD) concluded that breast feeding while introducing gluten to the diet reduced the risk of CD. The study was unable to determine if breastfeeding merely delayed symptoms or offered life-long protection.
An initial study at the University of Wisconsin found that women who were breast fed in infancy may have a lower risk of developing breast cancer than those who were not breast fed.
Breastfeeding may decrease the risk of cardiovascular disease in later life, as indicated by lower cholesterol and C-reactive protein levels in adult women who had been breastfed as infants. Although a 2001 study suggested that adults who had been breastfed as infants had lower arterial distensibility than adults who had not been breastfed as infants, the 2007 review for the WHO concluded that breastfed infants "experienced lower mean blood pressure" later in life. A 2007 review for the AHRQ found that "there is an association between a history of breastfeeding during infancy and a small reduction in adult blood pressure, but the clinical or public health implication of this finding is unclear". A 2006 study found that breastfed babies are better able to cope with stress later in life.
Doctors have long known that breast-fed infants are less likely to become overweight. A study in Today's Pediatrics associates solid food given too early to Formula-fed babies before 4 months old will make them 6 times as likely to become obese by age 3. It does not happen if the babies were given solid foods with breast feeding.
Benefits for mothers
Breastfeeding is a cost effective way of feeding an infant, providing nourishment for a child at a small cost to the mother. Frequent and exclusive breastfeeding can delay the return of fertility through lactational amenorrhea, though breastfeeding is an imperfect means of birth control. During breastfeeding beneficial hormones are released into the mother's body and the maternal bond can be strengthened. Breastfeeding is possible throughout pregnancy, but generally milk production will be reduced at some point.
Hormones released during breastfeeding help to strengthen the maternal bond. Teaching partners how to manage common difficulties is associated with higher breastfeeding rates. Support for a mother while breastfeeding can assist in familial bonds and help build a paternal bond between father and child.
If the mother is away, an alternative caregiver may be able to feed the baby with expressed breast milk. The various breast pumps available for sale and rent help working mothers to feed their babies breast milk for as long as they want. To be successful, the mother must produce and store enough milk to feed the child for the time she is away, and the feeding caregiver must be comfortable in handling breast milk.
Breastfeeding releases oxytocin and prolactin, hormones that relax the mother and make her feel more nurturing toward her baby. Breastfeeding soon after giving birth increases the mother's oxytocin levels, making her uterus contract more quickly and reducing bleeding. Pitocin, a synthetic hormone used to make the uterus contract during and after labour, is structurally modelled on oxytocin. Syntocinon, another synthetic oxytocic, is commonly used in Australia and the UK rather than Pitocin.
As the fat accumulated during pregnancy is used to produce milk, extended breastfeeding—at least 6 months—can help mothers lose weight. However, weight loss is highly variable among lactating women; monitoring the diet and increasing the amount/intensity of exercise are more reliable ways of losing weight. The 2007 review for the AHRQ found "The effect of breastfeeding in mothers on return-to-pre-pregnancy weight was negligible, and the effect of breastfeeding on postpartum weight loss was unclear."
Natural postpartum infertility
Breastfeeding may delay the return to fertility for some women by suppressing ovulation. A breastfeeding woman may not ovulate, or have regular periods, during the entire lactation period. The period in which ovulation is absent differs for each woman. This lactational amenorrhea has been used as an imperfect form of natural contraception, with greater than 98% effectiveness during the first six months after birth if specific nursing behaviors are followed. It is possible for women to ovulate within two months after birth while fully breastfeeding and get pregnant again.
Long-term health effects
For breastfeeding women, long-term health benefits include:
- Less risk of breast cancer, ovarian cancer, and endometrial cancer.
- A 2009 study indicated that lactation for at least 24 months is associated with a 23% lower risk of coronary heart disease.
- Although the 2007 review for the AHRQ found "no relationship between a history of lactation and the risk of osteoporosis", mothers who breastfeed longer than eight months benefit from bone re-mineralisation.
- Breastfeeding diabetic mothers require less insulin.
- Reduced risk of metabolic syndrome
- Reduced risk of post-partum bleeding.
- According to a Malmö University study published in 2009, women who breast fed for a longer duration have a lower risk for contracting rheumatoid arthritis than women who breast fed for a shorter duration or who had never breast fed.
Priscilla Colletto stated in Beyond Toddlerhood: The Breastfeeding Relationship Continues, “The adverse health effects of weaning a child before or during toddlerhood are well documented for Third World countries such as Guinea-Bissau, where children who were no longer breastfed at ages 12-35 months had a 3.5 times higher mortality rate than did their peers who continued to breastfeed.” Dr. Laurence Grummer-Strawn observed that breastfeeding is protective against diarrheal diseases and other infections, breastfed children aged 12 to 36 months in Indonesia have much greater mid-arm circumference than children who have been weaned, and the incidences of malnourishment in breastfed Indonesian children are 3-5% less common than generally encountered in Indonesian clinics. Studies suggest that extended breastfeeding may reduce the chances of otitis media allergies, leukemia, and lymphoma for the toddler, and premenopausal breast cancer in the mother. This is attributed to the fact that the levels of lysozyme, lactoferrin, and secretory IgA are stable and even increase in the breast milk of mothers who are breastfeeding for over 1 year. (Stein 1507). In one study, artificially-fed infants had 2 to 3 times as many episodes of significant illnesses (defined as “otitis media, lower respiratory disease, significant vomiting or diarrhea, and any illness requiring hospital admission”). However, there are also some studied risks involved in extended breastfeeding. Breastfeeding could impair a child's growth if they are not taught to eat other foods as well. Breast milk alone is not enough for children over 6 months of age and some have observed that children that have been breastfed longer than the norm have less of an appetite for added foods. Stein says that “As long as a toddler is eating a variety of grains, vegetables, fruits, and foods or supplements that provide adequate iron and vitamin D, nutrition will be adequate and appropriate growth and development will be ensured.”
In A Time to Wean by Katherine Dettwyler, it states that “Western, industrialized societies can compensate for some (but not all) of the immunological benefits of breastfeeding with antibiotics, vaccines and improved sanitation. But the physical, cognitive, and emotional needs of the young child persist.” Many children who are breast-fed into their toddler years use the milk as a comforting, bonding moment with their mothers. In a 1974 survey of 152 mothers, 17% said that the security their toddlers obtained through extended breastfeeding helped them become more independent, 14% said that extended breastfeeding created a strong mother-child bond, and 14.6% said that extended breastfeeding strengthened their abilities as a mother. Four mothers said that they felt their child was too dependent and one mother considered her child a poor eater. Dr. Stein said that “A mother in my practice who breastfed 2 children until 2 years of age explained that she would slowdown and give her undivided attention to her child several times each day when breastfeeding. Her children knew that she always had time for those moments each day. This time was also important to the mother for relaxing and unwinding....For many nursing toddlers, the breast comes to serve the same function as a favorite blanket or stuffed animal in providing comfort and a sense of security.” One issue with extended breastfeeding is the ability of the mother and the child to separate. Some say that the desire for extended breastfeeding comes from the mother's inability to let go of “her baby”. Baldwin refutes this statement, saying that the child is the one who chooses when they are weaned, as it is very difficult to force a child to breastfeed.(source:wikipedia.org)