Breastfeeding is both very rewarding for the mother and extremely important for both infant and maternal health.  Below are only a small portion of studies on the issue.  Unfortunately, in the U.S. only 64% of mothers breastfeed in 1^st month of life, and only 19% are still breast-feeding at 6 months. Rates are lowest for poor Afro-Americans.  This compares to 80% in Sweden for full-term infants at 6 months and 47% is the very prematurely delivered (Lakartidningen. 2004 Mar 11;101(11):990-3). 

Breast milk contains hormones, growth factors, cytokines, cells, antibodies, omega-3 fatty acids, and offers many advantages over cow's milk or soy protein infant formulae. Breastfeeding allows normal growth until at least 6 months of age, and can be prolonged until the age of 2 years or more, provided that complementary feeding is started after 6 months. Breastfeeding is associated with slightly enhanced performance on tests of cognitive development. Exclusive breastfeeding for at least 3 months is associated with a lower incidence and severity of diarrhea, otitis media and respiratory infection. Exclusive breastfeeding for at least 6 months is associated with a lower incidence of allergic disease in at-risk infants (infants with at least one first-degree relative presenting with allergy). Breastfeeding is also associated with a lower incidence of obesity during childhood and adolescence, as well as with a lower incidence of hypertension and hypercholesterolemia in adulthood. Maternal infection with hepatitis B and C virus is not a contraindication to breastfeeding, as opposed to HIV infection and galactosemia. A supplementation with vitamin D and K is necessary in the breastfed infant. Very few medications contraindicate breastfeeding. Premature babies can be breastfed and/or receive mother's milk and/or bank milk, provided they receive energy, protein and mineral supplements. Return to prepregnancy weight is earlier in breastfeeding mothers. Breastfeeding is also associated with a decreased risk of breast and ovarian cancer in the premenopausal period, and of hip fractures and osteoporosis in the postmenopausal period.

Infant Benefits

Allergies Lower in Breast-Fed: Maternal avoidance of highly-allergenic foods during pregnancy and lactation, prolonged exclusive breast-feeding, the use of a hydrolyzed milk formula, and delayed introduction of dairy products, eggs, fish, nuts and soybean are associated with a lower incidence of allergic symptoms and signs. Proc Nutr Soc 2000 May;59(2):273-7

Allergies Higher in Breast-Fed: Study of 1037 New Zealand young adults found twice the level of allergies and asthma in the 49% breast fed for at least 4 weeks. BMJ 9/28/02.

Allergic Dermatitis Lower in Breast-Fed in Best Study: Data on 3903 children were taken from yearly parental-administered questionnaires from a birth cohort study in Germany used multiple logistic regression and stratified by family history of allergy and by study group adjusting for a fixed set of risk factors for allergies. Exclusive breast-feeding (52 % of children) was not associated with higher risk for Atopic Dermatitis either in the entire cohort (OR(adj,) 0.95) or if stratified by family history of AD. Exclusive breast-feeding showed a significant protective effect on AD if compared with conventional cow's milk formula (OR(adj), 0.64). Effect of breast-feeding on the development of atopic dermatitis during the first 3 years of life--results from the GINI-birth cohort study. Laubereau B, Brockow I, Zirngibl A, Koletzko S, Gruebl A, von Berg A, Filipiak-Pittroff B, Berdel D, Bauer CP, Reinhardt D, Heinrich J, Wichmann HE; GINI Study Group, Neuherberg, Germany. J Pediatr. 2004 May;144(5):602-7

Blood Pressure Lower in Breast Fed: Lancet 2/10/01 = Adults bottle fed tend to have higher BP. Inst of Child Health in London took pre-mees 216 divided into three groups. One given donated breast milk, one pre-mee formula and one regular formula. 16 years later, BP of breast-fed were 2.7/3.2 lower.

Blood Pressure: Breast Feeding or DHA Formula Lower BP than Standard Formula: 1992 study in which 235 newborns were fed DHA- and AA-supplemented formula, regular baby formula, or mothers' milk. At the age of 6, the average diastolic blood pressure was three points lower in the fatty-acid fed group than the formula-fed group. 5/2/03. British Medical J 2003;326:953-955

Candida: Lower Thrush in Breast Fed: When the most abundant antibody was removed from breast milk, its anti-fungal capacity disappeared. The milk inhibits fungal growth. Yeast is also a cause of diaper rash. Candida is a leading cause of infection in pediatric AIDS. Sci News 6/2/2001.

Celiac Disease: Breast Feeding Protects: The risk of celiac disease was reduced in children aged <2 y if they were still being breast-fed when dietary gluten was introduced [adjusted odds ratio (OR): 0.59]. This effect was even more pronounced in infants who continued to be breast-fed after dietary gluten was introduced (OR: 0.36). The risk was greater when gluten was introduced in the diet in large amounts (OR: 1.5) than when introduced in small or medium amounts. In older children, these risk factors were of no or only minor importance. Am J Clin Nutr 2002 May;75(5):914-21 

Cystic Fibrosis Less Severe in the Exclusively Breast-Fed: 49% of 863 cystic fibrosis children surveyed received human breast milk at some time, but only 18% were exclusively breast-fed. Breast-feeding exclusively for greater than 6 months was associated with a decrease in disease severity based on intravenous antibiotic use in the previous two years compared to no breast-feeding (P = 0.03). There was also a trend toward delayed onset was seen in those receiving human milk. 53% of those who breast-fed exclusively > or = 6 months had FEV1% values > 90%, compared to 47% of those not breast-fed. Survey of breast-feeding practices and outcomes in the cystic fibrosis population. Parker EM, O'Sullivan BP, Shea JC, Regan MM, Freedman SD. University of Massachusetts Medical. Pediatr Pulmonol. 2004 Apr;37(4):362-7

Death Rate Lowered by Breastfeeding Exclusively At Least 6 Months: A reanalysis of studies in Brazil and Bangladesh has found that breastfed infants in the first six months of life who were given additional foods had a twofold to threefold higher mortality from diarrhea and pneumonia in comparison with infants who were exclusively breast fed. The only randomized controlled trials in a low income country (Honduras) found, like previous observational studies, that introducing fluids or foods into the infant's diet before 6 months of age did not benefit growth. supplementation with iron and zinc may be needed from about two months of age. BMJ 2002;325:1252-1253 (30 November)

Diarrhea: Breast Feeding Cuts, Esp. in Youngest: sent 483 of the women to counselors who provided education about the benefits of exclusively feeding children breast milk during the first six months of life. The other 412 women were not counseled. Among women who received counseling, 79 percent fed their babies only breast milk. This is compared to 48 percent in the group that received no counseling. Babies whose mothers had been counseled about breastfeeding were less likely to develop diarrhea, according to the report. At three months, they were 36 percent less likely to have diarrhea than children whose mothers had not been advised to breastfeed exclusively. At six months, they were 15 percent less likely to have diarrhea. Despite the differences in diet, babies in both groups were of comparable size and weight at the end of the study. Lancet 2003;361:1418-1423.

Diarrhea: Exclusive Breast-Feeding for 6 Months Better: Cochrane Database Syst Rev 2002;(1):CD003517. Review of literature found decrease diarrhea without any adverse effects in exclusively breast-fed in either developed or underdeveloped countries. A recent Italian study found better neurological functioning at 1 year in those exclusively breast fed at least 6 months vs. shorter periods of breast-feeding. Adv Exp Med Biol 2001;501:137-41

Heart Disease and Cholesterol: Breast Feeding Lowers: Teenagers who had already been studied as premature babies had been randomly assigned to be fed with either breast milk, standard formula milk or preterm formula. It was found those who had been given breast milk during infancy had a significantly lower ratio of bad to good cholesterol than those given formula milk, reducing their risk of developing heart disease. Teenagers who had been breast-fed had lower concentrations of CRP than those who had been given formula. Lancet, 5/14/04. Atul Singhal, Institute of Child Health, London. Breast-fed babies grow more slowly than those who are bottle-fed. Rapid early growth "programs" a baby's biology, making it prone to certain health conditions which increase the risk of developing heart disease and stroke, including obesity, high blood pressure, high cholesterol and a tendency to diabetes. Breast-fed babies are less likely to be overweight and have less chance of developing diabetes in childhood. Formula milk has been linked with a higher incidence of respiratory disease, high blood pressure, ear and urinary tract infections, diarrhea and gastroenteritis. Almost a third of women in England and Wales never try to breast-feed, compared to 2% in Sweden.

Intelligence: Higher IQs: Great Britain study showed breastfed had IQs 3-5 points higher. Greatest effect in those breastfed longest. Am J Clin Nutr 10/99. DHA may be a factor. Review of 20 other studies show breast-feeding associated with average 3.2 point increase in IQ.

Intelligence: Higher IQs: 3,253 Danish men and women, the more babies were breast-fed through 9 months of age, the higher they scored on intelligence tests in their late teens and 20s. Breast-feeding past 9 months had no additional effect on scores. breast-fed for seven to nine months scored an average of about six points higher on IQ tests than those whose mothers said they nursed for less than one month. Few participants had not breast-fed at all, although 1,000 breast-fed for under one month. JAMA 5/8/02

Lactobacilli: Children Receive Lactobacilli From Breast-Feeding Mothers: In a study of 178 breast-feeding infants and their mother showed that in each case mothers had Lactobacilli gasseri in their breast milk and that children had the identical strains in their mouth and feces. Human milk is a source of lactic acid bacteria for the infant gut. Martin R, Langa S, et al. J Pediatr. 2003 Dec;143(6):754-8

Mortality: 720 American Infants Die Each Year Due to Being Bottlefed Instead of Breastfed: In a U.S. nationwide study of CDC records of 1,204 children who died between 28 days and one year of causes other than congenital anomalies or cancer with those of 7,740 children still alive at one year, children who were breastfed had 20% lower risk of dying between 28 days and one year than children who weren't breastfed. Longer breastfeeding was associated with lower risk. The effect was the same in both African- and European-American children. Breastfed infants in the U.S. also have lower rates of illness, especially from infectious disease. If all mothers breastfed, 720 infant lives would be saved each year. Aimin Chen and Walter J Rogan. Pediatrics 05/05.

Obesity: Breast-Feeding Over 12 Months Associated with Less Obesity: Nutrition 2001 Nov-Dec;17(11-12):953-66. Author speculates an effect of LCPUFAs.

Over-Bite Prevented by Breast-Feeding: In a Harvard Dental School study of 126 children: (1) predominant bottle-feeding between 0 and 6 months of age was associated with the development of a pacifier habit; (2) children who used a pacifier were more likely to develop a nonmesial step occlusion, an overjet >3 mm, and an open bite; (3) children who sucked their thumb were more likely to develop an overjet >3 mm; and (4) children who were predominantly bottle-fed between 0 and 6 months of age were more likely to develop an overbite >75%. The effects of infant feeding patterns on the occlusion of the primary dentition. Charchut SW, Allred EN, Needleman HL. J Dent Child (Chic). 2003 Sep-Dec;70(3):197-203

Pain from Blood Drawing Less if Drawn While Baby Breast-Feeding: Crying and grimacing were reduced by 91% and 84%, respectively, from control infant levels during the blood collection. Heart rate was also substantially reduced by breastfeeding. Breastfeeding is a potent analgesic intervention in newborns during a standard blood collection. Pediatrics 2002 Apr;109(4):590-3 

Salmonella Infections Rare in Breast-Fed: In 1996, U.S. children under 12 months of age had the highest incidence of sporadic salmonellosis. Twenty-two case patients were matched with 39 control subjects by age and either telephone exchange or vital record birth list. In a multivariate analysis, case patients were more likely to have a liquid diet containing no breast milk than a liquid diet containing only breast milk (odds ratio, 44.5; P=.04). Case-patients were more likely to reside in a household where a member had diarrhea (odds ratio, 13.2; P=.01). Breast-feeding decreases the risk of sporadic salmonellosis among infants in FoodNet sites. Rowe SY, Rocourt JR, Shiferaw B, Kassenborg HD, Segler SD, Marcus R, Daily PJ, Hardnett FP, Slutsker L; Emerging Infections Program FoodNet Working Group. CDC. Clin Infect Dis. 2004 Apr 15;38 Suppl 3:S262-70

Schizophrenia: Breast-Feeding Protective Against Schizophrenia: In a study of 6841 adults from the Copenhagen Perinatal Cohort of whom 1671 (24%) had been breastfed for 2 weeks or less (early weaning) and 5170 (76%) had been breastfed longer, 93 developed schizophrenia (1.4%). Maternal schizophrenia was the strongest risk factor and a significant association between single mother status and elevated offspring risk of schizophrenia was also observed. Early weaning was significantly related to later schizophrenia (adjusted odds ratio 1.73). Breastfeeding and risk of schizophrenia in the Copenhagen Perinatal Cohort. Sorensen HJ, et al. Copenhagen University Hospital, Denmark. Acta Psychiatr Scand. 2005 Jul;112(1):26-9

Thumb-Sucking Decreased by Breast-Feeding and Lack of Pacifier: In a study of 81 thumb-suckers and 80 non-suckers, about 79% of non-suckers had been breast-fed for more than 6 months while only 43.2% of digit suckers were breast-fed for the same duration. More digit suckers (22.2%) than non-suckers (12.5%) were reported to have a history of pacifier use. The digit sucking habit and related factors: observations from a child dental health clinic in Nigeria. daCosta OO, Orenuga OO. University of Lagos, Nigeria.

Tooth Wear Increased by Early Weaning: Tooth wear associated with dentine exposure is common in 5-8 year old children. This is not significantly associated with dietary factors, but appears to be related to early weaning from the breast. Risk indicators for tooth wear in New Zealand school children. Ayers KM, Drummond BK, Thomson WM, Kieser J. Int Dent J. 2002 Feb;52(1):41-6

Vegetarians Breast-Feeding Moms Need B-12 and Vitamin D Supplements: Ned Tijschrik 2006 Mar 4;150(9):473-5.

Vitamin D Supplement Needed: In a study of 45 mothers and their children, 40% of the infants had low 25-(OH)D levels less than 50 nmol/L, and 31% had deficient levels under 30 nmol/L. Twelve of 16 breastfed infants had 25-(OH)D levels < 30 nmol/L, compared with 2/29 fed formula milk (P = 0.001). Postnatal evaluation of vitamin D and bone health in women who were vitamin D-deficient in pregnancy, and in their infants. Thompson K, Morley R, et al. Royal Children's Hospital, Australia. Med J Aust. 2004 Nov 1;181(9):486-8. Ed: At least 2000 IU of vitamin D per day is recommended while nursing by one author measuring vitamin D levels in breast milk.

Vitamin D Recommended: Authors state that the recommended 400 IU/day of vitamin D is inadequate for nursing mothers and infants.  In a study of 18 nursing mothers, 2000 IU/day for 3 months raised the levels in the breast milk by 34.2 IU/L, while 4000 IU/d increased levels by 94.2 IU/L, which the authors thought were still better. Vitamin D requirements during lactation: high-dose maternal supplementation as therapy to prevent hypovitaminosis D for both the mother and the nursing infant. Hollis BW, Wagner CL. Medical University of South Carolina. Am J Clin Nutr. 2004 Dec;80. Ed: Low vitamin D in infants results in slower growth and reduced size. Am J Clin Nutr. 2004 Dec;80(6 Suppl):1748S-51S. Vitamin D supplementation markedly reduces the risk of diabetes and schizophrenia in the children.  

Nortriptyline, Sertraline (Zoloft) Lowest in Breast Milk; Fluoxetine, Citalopram (Celexa, Lexapro) Highest: In a review of all research from 1966 to 2002, the authors identified 57 studies of maternal plasma, breast milk, and/or infant plasma antidepressant levels from nursing mother-infant pairs, measured by liquid chromatography. Nortriptyline, paroxetine, and sertraline usually produce undetectable infant levels. Fluoxetine produces the highest proportion (22%) of infant levels that are elevated above 10% of the average maternal level. Citalopram produced elevated levels in 17% of infants. Pooled analysis of antidepressant levels in lactating mothers, breast milk, and nursing infants. Weissman AM, Levy BT, Hartz AJ, Bentler S, Donohue M, Ellingrod VL, Wisner KL. Am J Psychiatry. 2004 Jun;161(6):1066-78

Olanzapine (Zyprexa) in Breast Milk Very Low: A study of six breast fed children with mothers on olanzapine found the infant exposure calculated at 1% of the maternal dose. The children had no measurable blood levels. Levels in breast milk peaked 5 hours after the maternal dosing. The authors conclude, "These data support the use of olanzapine during breast-feeding." Gardiner S, et al: Transfer of olanzapine into breast milk, calculation of infant drug dose, and effect on breast-fed infants. Am J Psychiatry 2003;160:1428-31.

Doxepin Cases But OK in 800: A report of two children with neurological problems from doxepin led to a study of 800 breast-feeding women on the medication. It found only 11% of children were affected and all minor (drowsiness, etc.). Prescrire Int 2002 Feb;11(57):17. For women on sertraline, breast-feeding had no impact on infants. Am J Psychiatry 2001 Oct;158(10):1631-7

Infant Weight Gain Not Affected by Breast-Feeding Mothers’ Anti-depressants: 78 breast-feeding mothers on SSRIs or venlafaxine studied (6 on tricyclics, too.). Their children gained exactly the average CDC norms over 6 months. The eleven children of mothers with over 2 months of post-partum depression did gain less than average. Hendrick V, Smith L, et al: Weight gain in breastfed infants of mothers taking antidepressant medications. J Clin Psychiatry 2003;64:410-2. UCLA