Prolonged and Exclusive Breastfeeding Reduces the Risk of Infectious Diseases in Infancy Effect of prolonged and exclusive breast feeding on risk of allergy and asthma: cluster randomised trial Breastfeeding and child cognitive development: new evidence from a large randomized trial. Association between breast feeding and asthma in 6 year old children: findings of a prospective birth cohort study Early short-term infant food supplementation, maternal weight loss and duration of breast-feeding: a randomised controlled trial in rural Senegal Effects of exclusive breastfeeding for four versus six months on maternal nutritional status and infant motor development: results of two randomized trials in Honduras. Infant growth and health outcomes associated with 3 compared with 6 mo of exclusive breastfeeding. Effects of age of introduction of complementary foods on iron status of breast-fed infants in Honduras. Effects of prolonged and exclusive breastfeeding on child height, weight, adiposity, and blood pressure at age 6.5 y: evidence from a large randomized trial. Age of introduction of complementary foods and growth of term, low-birth-weight, breast-fed infants: a randomized intervention study in Honduras. Effects of age at introduction of complementary foods to breast-fed infants on duration of lactational amenorrhea in Honduran women. Cumulative incidence of atopic disorders in high risk infants fed whey hydrolysate, soy, and conventional cow milk formulas. Exclusive breast-feeding for at least 4 months protects against otitis media. Breast-feeding and the nutritional status of nursing children in Chile. The association between duration of breastfeeding and adult intelligence. PROLONGED BREAST-FEEDING AS PROPHYLAXIS FOR ATOPIC DISEASE Effects of age of introduction of complementary foods on infant breast milk intake, total energy intake, and growth: a randomised intervention study in Honduras Growth and nutrient intake in three- to twelve-month-old infants fed human milk or formulas with varying protein concentrations. The first six month growth and illness of exclusively and non-exclusively breast-fed infants in Nigeria. Reduced Risk of IDDM Among Breast-Fed Children: The Colorado IDDM Registry Influence of breastfeeding and other reproductive factors on bone mass later in life Determinants of growth from birth to 12 months among breast-fed Honduran infants in relation to age of introduction of complementary foods. Health and development outcomes in 6.5-y-old children breastfed exclusively for 3 or 6 mo. Breastfeeding and the risk of sudden infant death syndrome. Influence of breastfeeding and complementary food on growth between 5 and 10 months Promotion of Breastfeeding Intervention Trial (PROBIT): a randomized trial in the Republic of Belarus. Breastfeeding and infant size: evidence of reverse causality. Breastfeeding and breast cancer risk INFANT GROWTH AND HUMAN MILK REQUIREMENTS: A Fresh Approach The need for randomization in the study of intended effects. Breastfeeding and infant growth: biology or bias? Do Exclusively Breast-Fed Infants Require Extra Protein?
OBJECTIVE : To examine the associations of duration of exclusive breastfeeding with infections in the upper respiratory ( URTI ) , lower respiratory ( LRTI ) , and gastrointestinal tracts ( GI ) in infancy . METHODS : This study was embedded in the Generation R Study , a population -based prospect i ve cohort study from fetal life onward in the Netherl and s. Rates of breastfeeding during the first 6 months ( never ; partial for < 4 months , not thereafter ; partial for 4–6 months ; exclusive for 4 months , not thereafter ; exclusive for 4 months , partial thereafter ; and exclusive for 6 months ) and doctor-attended infections in the URTI , LRTI , and GI until the age of 12 months were assessed by question naires and available for 4164 subjects . RESULTS : Compared with never-breastfed infants , those who were breastfed exclusively until the age of 4 months and partially thereafter had lower risks of infections in the URTI , LRTI , and GI until the age of 6 months ( adjusted odds ratio [ aOR ] : 0.65 [ 95 % confidence interval ( CI ) : 0.51–0.83 ] ; aOR : 0.50 [ CI : 0.32–0.79 ] ; and aOR : 0.41 [ CI : 0.26–0.64 ] , respectively ) and of LRTI infections between the ages of 7 and 12 months ( aOR : 0.46 [ CI : 0.31–0.69 ] ) . Similar tendencies were observed for infants who were exclusively breastfed for 6 months or longer . Partial breastfeeding , even for 6 months , did not result in significantly lower risks of these infections . CONCLUSIONS : Exclusive breastfeeding until the age of 4 months and partially thereafter was associated with a significant reduction of respiratory and gastrointestinal morbidity in infants . Our findings support health-policy strategies to promote exclusive breastfeeding for at least 4 months , but preferably 6 months , in industrialized countries Objective To assess whether exclusive and prolonged breast feeding reduces the risk of childhood asthma and allergy by age 6.5 years . Design Cluster r and omised trial . Setting 31 Belarussian maternity hospitals and their affiliated polyclinics . Participants A total of 17 046 mother-infant pairs were enrolled , of whom 13 889 ( 81.5 % ) were followed up at age 6.5 years . Intervention Breastfeeding promotion intervention modelled on the WHO/UNICEF baby friendly hospital initiative . Main outcome measures International study of asthma and allergies in childhood ( ISAAC ) question naire and skin prick tests of five inhalant antigens . Results The experimental intervention led to a large increase in exclusive breast feeding at 3 months ( 44.3 % v 6.4 % ; P<0.001 ) and a significantly higher prevalence of any breast feeding at all ages up to and including 12 months . The experimental group had no reduction in risks of allergic symptoms and diagnoses or positive skin prick tests . In fact , after exclusion of six sites ( three experimental and three control ) with suspiciously high rates of positive skin prick tests , risks were significantly increased in the experimental group for four of the five antigens . Conclusions These results do not support a protective effect of prolonged and exclusive breast feeding on asthma or allergy . Trial registration Current Controlled Trials IS RCT N37687716 CONTEXT The evidence that breastfeeding improves cognitive development is based almost entirely on observational studies and is thus prone to confounding by subtle behavioral differences in the breastfeeding mother 's behavior or her interaction with the infant . OBJECTIVE To assess whether prolonged and exclusive breastfeeding improves children 's cognitive ability at age 6.5 years . DESIGN Cluster-r and omized trial , with enrollment from June 17 , 1996 , to December 31 , 1997 , and follow-up from December 21 , 2002 , to April 27 , 2005 . SETTING Thirty-one Belarussian maternity hospitals and their affiliated polyclinics . PARTICIPANTS A total of 17,046 healthy breastfeeding infants were enrolled , of whom 13,889 ( 81.5 % ) were followed up at age 6.5 years . INTERVENTION Breastfeeding promotion intervention modeled on the Baby-Friendly Hospital Initiative by the World Health Organization and UNICEF . MAIN OUTCOME MEASURES Subtest and IQ scores on the Wechsler Abbreviated Scales of Intelligence , and teacher evaluations of academic performance in reading , writing , mathematics , and other subjects . RESULTS The experimental intervention led to a large increase in exclusive breastfeeding at age 3 months ( 43.3 % for the experimental group vs 6.4 % for the control group ; P < .001 ) and a significantly higher prevalence of any breastfeeding at all ages up to and including 12 months . The experimental group had higher means on all of the Wechsler Abbreviated Scales of Intelligence measures , with cluster-adjusted mean differences ( 95 % confidence intervals ) of + 7.5 ( + 0.8 to + 14.3 ) for verbal IQ , + 2.9 ( -3.3 to + 9.1 ) for performance IQ , and + 5.9 ( -1.0 to + 12.8 ) for full-scale IQ . Teachers ' academic ratings were significantly higher in the experimental group for both reading and writing . CONCLUSION These results , based on the largest r and omized trial ever conducted in the area of human lactation , provide strong evidence that prolonged and exclusive breastfeeding improves children 's cognitive development . TRIAL REGISTRATION is rct n.org Identifier : IS RCT N37687716 Abstract Objectives : To investigate the association between the duration of exclusive breast feeding and the development of  asthma related outcomes in children at age 6 years . Design : Prospect i ve cohort study . Setting : Western Australia . Subjects : 2187 children ascertained through antenatal clinics at the major tertiary obstetric hospital in Perth and followed to age 6 years . Main outcome measures : Unconditional logistic regression to model the association between duration of exclusive breast feeding and outcomes related to asthma or atopy at 6 years of age , allowing for several important confounders : sex , gestational age , smoking in the household , and early childcare . Results : After adjustment for confounders , the introduction of milk other than breast milk before 4 months of age was a significant risk factor for all asthma and atopy related outcomes in children aged 6 years : asthma diagnosed by a doctor ( odds ratio 1.25 , 95 % confidence interval 1.02 to 1.52 ) ; wheeze three or more times since 1 year of age ( 1.41 , 1.14 to 1.76 ) ; wheeze in the past year ( 1.31 , 1.05 to 1.64 ) ; sleep disturbance due to wheeze within the past year ( 1.42 , 1.07 to 1.89 ) ; age when doctor diagnosed asthma ( hazard ratio 1.22 , 1.03 to 1.43 ) ; age at first wheeze ( 1.36 , 1.17 to 1.59 ) ; and positive skin prick test reaction to at least one common aeroallergen ( 1.30 , 1.04 to 1.61 ) . Conclusion : A significant reduction in the risk of childhood asthma at age 6 years occurs if exclusive breast feeding is continued for at least the 4 months after birth . These findings are important for our underst and ing of the cause of childhood asthma and suggest that public health interventions to optimise breast feeding may help to reduce the community burden of childhood asthma and its associated traits . Key messages Asthma is the leading cause of admission to hospital in Australian children and its prevalence is increasing Whether breast feeding protects against asthma or atopy , or both , is controversial Asthma is a complex disease , and the relative risks between breast feeding and asthma or atopy are unlikely to be large ; this suggests the need for investigation in a large prospect i ve birth cohort with timely assessment of atopic outcomes and all relevant exposures Exclusive breast feeding for at least 4 months is associated with a significant reduction in the risk of asthma and atopy at age 6 years and with a significant delay in the age at onset of wheezing and asthma being diagnosed by a doctor Public health interventions to promote an increased duration of exclusive breast feeding may help to reduce the morbidity and prevalence of childhood asthma  and Objective : Early supplementation of breastfed infants may have consequences both for the mother and the child . We hypothesised that it would result in decreased maternal weight loss and in shorter duration s of breastfeeding and birth intervals . Design : Controlled r and omised population -based trial . Setting : Six villages in the Sine area of Senegal , West Africa . Subjects : Healthy breastfed infants and their mothers , 68 controls and 66 supplemented infants at r and omization . Intervention : Supplementation with high-energy , nutrient dense food from 4 to 7 months of age , twice daily under supervision of field workers . Both controls and supplemented infants were free to eat other complementary foods .  Maternal weight was measured monthly . Date s of breastfeeding cessation and of subsequent births were collected prospect ively through weekly demographic surveillance , and were analysed using Cox 's regression models and ‘ intent-to-supplement ’ approach . Results : Mean maternal weight gain from 4 to 7 months postpartum tended to be greater in the supplemented group ( + 0.25 kg/months , 95 % confidence interval ( CI ) : −0.07 , + 0.57 ) . Supplemented infants were breastfed for significantly longer duration s than controls ( medians : 24.9 and 23.7 months , respectively , P : 0.034 ) . Their adjusted hazard ratio ( HR ) for breastfeeding cessation was 0.59 ( 95 % CI : 0.40 , 0.89 ) . Their mothers had a lower risk of a new birth than mothers of controls ( adjusted HR : 0.57 , 95 % CI : 0.36 , 0.92 ) . Conclusions : Early short-term infant supplementation tended to decrease maternal postpartum weight loss , but it increased , rather than shortened , the duration of breastfeeding and birth interval . Sponsorship : This study was supported by a grant from the French Ministry of Research ( Grant 92L0623 ) To examine whether the duration of exclusive breastfeeding affects maternal nutrition or infant motor development , we examined data from two studies in Honduras : the first with 141 infants of low-income primiparous women and the second with 119 term , low birth weight infants . In both studies , infants were exclusively breastfed for 4 mo and then r and omly assigned to continue exclusive breastfeeding ( EBF ) until 6 mo or to receive high- quality , hygienic solid foods ( SF ) in addition to breast milk between 4 and 6 mo .  Maternal weight loss between 4 and 6 mo was significantly greater in the exclusive breastfeeding group ( EBF ) group than in the group(s ) given solid foods ( SF ) in study 1 ( -0.7 + /- 1.5 versus -0.1 + /- 1.7 kg , P < 0.05 ) but not in study 2 . The estimated average additional nutritional burden of continuing to exclusively breastfeed until 6 mo was small , representing only 0.1 - 6.0 % of the recommended dietary allowance for energy , vitamin A , calcium and iron . Women in the EBF group were more likely to be amenorrheic at 6 mo than women in the SF group , which conserves nutrients such as iron . In both studies , few women ( 10 - 11 % ) were thin ( body mass index < 19 kg/m(2 ) ) , so the additional weight loss in the EBF group in study 1 was unlikely to have been detrimental . Infants in the EBF group crawled sooner ( both studies ) and were more likely to be walking by 12 mo ( study 1 ) than infants in the SF group . Taken together with our previous findings , these results indicate that the advantages of exclusive breastfeeding during this interval appear to outweigh any potential disadvantages in this setting BACKGROUND Opinions and recommendations about the optimal duration of exclusive breastfeeding have been strongly divided , but few published studies have provided direct evidence on the relative risks and benefits of different breastfeeding duration s in recipient infants . OBJECTIVE We examined the effects on  infant growth and health of 3 compared with 6 mo of exclusive breastfeeding . DESIGN We conducted an observational cohort study nested within a large r and omized trial in Belarus by comparing 2862 infants exclusively breastfed for 3 mo ( with continued mixed breastfeeding through > /= 6 mo ) with 621 infants who were exclusively breastfed for > /= 6 mo .  Regression to the mean , within-cluster correlation , and cluster- and individual-level confounding variables were accounted for by using multilevel regression analyses . RESULTS From 3 to 6 mo , weight gain was slightly greater in the 3-mo group [ difference : 29 g/mo ( 95 % CI : 13 , 45 g/mo ) ] , as was length gain [ difference : 1.1 mm ( 0.5 , 1.6 mm ) ] , but the 6-mo group had a faster length gain from 9 to 12 mo [ difference : 0.9 mm/mo ( 0.3 , 1.5 mm/mo ) ] and a larger head circumference at 12 mo [ difference : 0.19 cm ( 0.07 , 0.31 cm ) ] . A significant reduction in the incidence density of gastrointestinal infection was observed during the period from 3 to 6 mo in the 6-mo group [ adjusted incidence density ratio : 0.35 ( 0.13 , 0.96 ) ] , but no significant differences in risk of respiratory infectious outcomes or atopic eczema were apparent . CONCLUSIONS Exclusive breastfeeding for 6 mo is associated with a lower risk of gastrointestinal infection and no demonstrable adverse health effects in the first year of life To evaluate the effect of introducing complementary foods before 6 mo of age , we r and omly assigned 164 infants who had been exclusively breast-fed for 4 mo to continue being exclusively breast-fed until 6 mo ( EBF group ) or to receive iron-fortified foods in addition to breast milk from 4 to 6 mo ( BF+SF group ) . At 6 mo , the BF+SF group had higher mean iron intake ( 4 mg/d compared with 0.2 mg/d in EBF infants ) and higher hemoglobin , hematocrit , and ferritin values than the EBF group ( P < 0.05 ) . The percentage with low hemoglobin ( < 103 g/L ) did not differ significantly between groups , but fewer infants in the BF+SF group had a low hematocrit ( < 0.33 ; 21.4 % compared with 32.0 % , respectively ; P < 0.05 ) . The percentage of infants with ferritin concentrations < 12 microg/L at 6 mo was lower than the percentage with low hemoglobin or hematocrit , raising questions about the validity of the cutoffs at this age . Infants at greatest risk for anemia and low ferritin were those with birth weights < 2500 g ; no infant with a birth weight > 3000 g had a low ferritin value at 6 mo . We conclude that the risk of iron deficiency is low among infants with birth weights > 3000 g who are exclusively breast-fed for 6 mo . Iron drops are recommended for low-birth-weight infants ; for breast-fed infants with birth weights between 2500 and 3000 g , further research is needed to determine whether iron drops are more effective than complementary foods for preventing iron deficiency before 6 mo BACKGROUND The evidence that breastfeeding protects against obesity and a variety of chronic diseases comes almost entirely from observational studies , which have a potential for bias due to confounding , selection bias , and selective publication . OBJECTIVE We assessed whether an intervention design ed to promote exclusive and prolonged breastfeeding affects children 's height , weight , adiposity , and blood pressure at age 6.5 y. DESIGN The Promotion of Breastfeeding Intervention Trial ( PROBIT ) is a cluster-r and omized trial of a breastfeeding promotion intervention based on the WHO/UNICEF Baby-Friendly Hospital Initiative . A total of 17,046 healthy breastfed infants were enrolled from 31 Belarussian maternity hospitals and their affiliated clinics ; of those infants , 13,889 ( 81.5 % ) were followed up at 6.5 y with duplicate measurements of anthropometric variables and blood pressure . Analysis was based on intention to treat , with statistical adjustment for clustering within hospitals or clinics to permit inferences at the individual level . RESULTS The experimental intervention led to a much greater prevalence of exclusive breastfeeding at 3 mo in the experimental than in the control group ( 43.3 % and 6.4 % , respectively ; P < 0.001 ) and a higher prevalence of any breastfeeding throughout infancy . No significant intervention effects were observed on height , body mass index , waist or hip circumference , triceps or subscapular skinfold thickness , or systolic or diastolic blood pressure . CONCLUSIONS The breastfeeding promotion intervention result ed in substantial increases in the duration and exclusivity of breastfeeding , yet it did not reduce the measures of adiposity , increase stature , or reduce blood pressure at age 6.5 y in the experimental group . Previously reported beneficial effects on these outcomes may be the result of uncontrolled confounding and selection bias BACKGROUND The optimal age at which to introduce complementary foods is a topic of considerable debate . OBJECTIVE This study was design ed to evaluate this issue in a nutritionally vulnerable population in Honduras . DESIGN Mothers of low-birth-weight ( 1500 - 2500 g ) term ( ie , small-for-gestational-age ) infants were recruited in the hospital and assisted with exclusive breast-feeding during the first 4 mo . At 4 mo , mothers were r and omly assigned to either continue exclusive breast-feeding to 6 mo ( EBF ; n = 59 ) or to feed complementary solid foods ( jarred rice cereal , chicken , and fruit and vegetables ) twice daily from 4 to 6 mo while continuing to breast-feed at their initial frequency ( SF ; n = 60 ) . At 4 and 6 mo , breast milk and total energy intake were measured for a nonr and om sub sample ( those who could stay overnight in a central unit : 32 EBF and 31 SF ) . RESULTS At 4 mo , breast milk intake in the sub sample was not significantly different between groups ( EBF : 729 + /- 135 g/d ; SF : 683 + /- 151 g/d : P > 0.2 ) ; from 4 to 6 mo it increased ( by 28 g/d ) in the EBF group but decreased ( by 39 g/d ) in the SF group ( P < 0.005 ) . Nonetheless , total energy intake ( including solid foods ) increased more from 4 to 6 mo in the SF than in the EBF group . However , there were no significant differences between groups in weight or length gain during the intervention or subsequently ( 6 - 12 mo ) . CONCLUSION There was no growth advantage of complementary feeding of small-for-gestational-age , breast-fed infants between 4 and 6 mo of age Lactational  amenorrhea  ( LA ) is associated with postpartum infertility and is known to be related to breast-feeding frequency and duration , but the exact role of complementary feeding of the infant has not been clearly defined . Data on LA were collected during and after a 2-mo intervention trial in which low-income Honduran women who had breast-fed fully for 4 mo were r and omly assigned to one of three groups : continued full breast-feeding until 6 mo ( FBF , n = 50 ) , introduction of complementary foods at 4 mo with ad libitum breast-feeding from 4 to 6 mo ( SF , n = 47 ) , or introduction of complementary foods at 4 mo with maintenance of baseline breast-feeding frequency from 4 to 6 mo ( SF-M , n = 44 ) . Women were followed up until the infant was 12 mo of age , or later if menses had not occurred by then . All but six of the women continued to breast-feed for > or = 12 mo . With the exclusion of those whose menses returned before 18 wk postpartum ( which could not have been due to the intervention ) , the proportion of women who were amenorrheic at 6 mo was 64.5 % in the SF group , 80.0 % in the FBF group , and 85.7 % in the SF-M group ( chi-square test = 4.13 , P = 0.02 ; one-tailed test with the latter two groups combined ) . The total duration of LA did not differ significantly among groups . The most significant determinant of LA was time spent breast-feeding ( min/d ) , which was in turn negatively associated ( P = 0.06 ) with the infant 's energy intake from complementary foods in regression analyses . These results indicate that there is a significant effect of introducing foods at 4 mo on the likelihood of amenorrhea at 6 mo postpartum , but not thereafter , and that this effect is not seen in mothers who maintain breast-feeding frequency A recent increase in the prevalence of atopic disorders and the enormous costs of management of atopic patients have prompted attempts at prevention . We have examined the effect of exclusive breast feeding and of feeding different infant formulas on incidence of atopic disease in a prospect i ve r and omized controlled study . Seventy-two infants were recruited into each of the following groups : cow milk whey hydrolysate formula ( NAN/HA ) conventional cow milk formula ( Similac ) , soy-based formula ( Isomil ) , and exclusive breast feeding for greater than 4 months .  The cumulative incidence of atopic eczema , recurrent wheezing , rhinitis , gastrointestinal symptoms , and colic were noted . Skin prick tests and radioallergosorbent tests for IgE antibodies to milk and soy were performed . At 12 and 18 months of age , the incidence of atopic eczema as also that of all atopic symptoms was significantly lower and similar in the breast-fed and whey hydrolysate groups , compared with the cow milk and soy formula groups . IgE antibodies were detected more often in the cow milk and soy formula groups , especially the former . Among symptomatic infants , fewer skin positive prick tests were seen in the soy group compared with the cow milk group . Our observations show that among infants at high risk of developing atopic disease because of positive family history , exclusive breast feeding or whey hydrolysate formula is associated with a lower incidence and thus a delay in the occurrence of allergic disorders compared with groups fed conventional cow milk or soy formulas OBJECTIVE This study was design ed to assess the relation of exclusive breast-feeding , independent of recognized risk factors , to  acute and recurrent otitis media in the first 12 months of life . METHODS Records of 1220 infants who used a health maintenance organization and who were followed during their first year of life as part of the Tucson Children 's Respiratory Study were review ed . Detailed prospect i ve information about the duration and exclusiveness of breast-feeding was obtained , as was information relative to potential risk factors ( socioeconomic status , gender , number of siblings , use of day care , maternal smoking , and family history of allergy ) . Acute otitis media and recurrent otitis media , defined as three or more episodes of acute otitis media in a 6-month period or four episodes in 12 months , were the outcome variables . RESULTS Of the 1013 infants followed for their entire first year , 476 ( 47 % ) had at least one episode of otitis and 169 ( 17 % ) had recurrent otitis media . Infants exclusively breast-fed for 4 or more months had half the mean number of acute otitis media episodes as did those not breastfed at all and 40 % less than those infants whose diets were supplemented with other foods prior to 4 months . The recurrent otitis media rate in infants exclusively breast-fed for 6 months or more was 10 % and was 20.5 % in those infants who breast-fed for less than 4 months . This protection was independent of the risk factors considered . CONCLUSION These findings suggest that exclusive breast-feeding of 4 or more months protected infants from single and recurrent episodes of otitis media The work reported here sought to describe the feeding patterns of Chilean children up to 18 months old and their relation to nutritional status . To this end , a survey was conducted in 1993 of 9330 Chilean children under 18 months old who were receiving care through the National Health Service System-which provides care for 75 % of all children under age 6 . The children , whose mothers or caretakers were interviewed , constituted 94 % of a sample selected at r and om from 102 of the 320 urban health clinics located throughout the country . The interview served to identify the type of feeding ( exclusive breast-feeding , breast-feeding plus bottle-feeding , breast-feeding plus solid food , exclusive bottle-feeding , or bottle-feeding plus solid food ) and to determine the nutritional status of the participants in terms of st and ards used by the United States National Center for Health Statistics and the World Health Organization . Children were deemed at risk of malnutrition if they had z scores on the weight-for-age distribution between 1.0 and 2.0 st and ard deviations below the US/WHO st and ard and as actually malnourished if they had z scores of over 2.0 st and ard deviations below the st and ard . The survey found exclusive breast-feeding prevalences of 86.5 % , 66.7 % , and 25.3 % among infants 1 , 3 , and 6 months old . Some 12.1 % of the participants were found to have a weight-for-age deficiency , 30.7 % exhibited a height-for-age deficiency , and 35.7 % were found to be over-weight . The prevalence of weight-for-age and height-for-age deficiencies were found to be considerably higher among bottle-fed children than among breast-fed children . In general , the results demonstrated the benefits of exclusive breast-feeding through the first 6 months of life , the need to complement exclusive breast-feeding with solid food after that time , and the superior nutritional status of breast-fed children within the age groups studied CONTEXT A number of studies suggest a positive association between breastfeeding and cognitive development in early and middle childhood . However , the only previous study that investigated the relationship between breastfeeding and intelligence in adults had several method ological shortcomings . OBJECTIVE To determine the association between duration of infant breastfeeding and intelligence in young adulthood . DESIGN , SETTING , AND PARTICIPANTS Prospect i ve longitudinal birth cohort study conducted in a sample of 973 men and women and a sample of 2280 men , all of whom were born in Copenhagen , Denmark , between October 1959 and December 1961 . The sample s were divided into 5 categories based on duration of breastfeeding , as assessed by physician interview with mothers at a 1-year examination . MAIN OUTCOME MEASURES Intelligence , assessed using the Wechsler Adult Intelligence Scale ( WAIS ) at a mean age of 27.2 years in the mixed-sex sample and the Børge Priens Prøve ( BPP ) test at a mean age of 18.7 years in the all-male sample . Thirteen potential confounders were included as covariates : parental social status and education ; single mother status ; mother 's height , age , and weight gain during pregnancy and cigarette consumption during the third trimester ; number of pregnancies ; estimated gestational age ; birth weight ; birth length ; and indexes of pregnancy and delivery complications . RESULTS Duration of breastfeeding was associated with significantly higher scores on the Verbal , Performance , and Full Scale WAIS IQs . With regression adjustment for potential confounding factors , the mean Full Scale WAIS IQs were 99.4 , 101.7 , 102.3 , 106.0 , and 104.0 for breastfeeding duration s of less than 1 month , 2 to 3 months , 4 to 6 months , 7 to 9 months , and more than 9 months , respectively ( P = .003 for overall F test ) . The corresponding mean scores on the BPP were 38.0 , 39.2 , 39.9 , 40.1 , and 40.1 ( P = .01 for overall F test ) . CONCLUSION Independent of a wide range of possible confounding factors , a significant positive association between duration of breastfeeding  and intelligence was observed in 2 independent sample s of young adults , assessed with 2 different intelligence tests 54 babies who had been solely breast-fed for more than 6 months , 77 babies who had been breast-fed for 2 - -6 months , and 105 babies who had been weaned to cow's-milk-based formulas at less than 2 months were followed for the first 3 years of life . All the babies had the same pattern of solid food intake until 1 year of age . Compared with formula feeding , prolonged breast-feeding result ed in a lower incidence of severe or obvious atopic disease particularly in babies with family history of atopy In developing countries , the age at which breastfed infants are first given complementary foods is of public health importance because of the risk of diarrhoeal disease from contaminated weaning foods , and the potential risk of growth faltering if foods are inappropriately delayed . To evaluate whether there are any advantage of complementary feeding prior to 6 months , low-income primiparous mothers who had exclusively breastfed for 4 months were r and omly assigned to one of 3 groups : continued exclusive breastfeeding to 6 months ( EBF ) ( n = 50 ) ; introduction of complementary foods at 4 months with ad libitum nursing from 4 - 6 months ( SF ) ( n = 47 ) ; and introduction of complementary foods at 4 months , with maintenance of baseline nursing frequency from 4 - 6 months ( SF-M ) ( n = 44 ) . Baby foods in jars were provided to the SF and SF-M groups from 4 to 6 months . Subjects were visited weekly and provided with lactation guidance ; at 4 , 5 , and 6 months measurements were made of infant intake and breast milk composition . At 4 months , breast milk intake averaged 797 ( 139 ) g per day ( no difference among groups ) . Between 4 and 6 months , breast milk intake was unchanged in EBF infants ( + 6 ) but decreased in the SF ( -103 ) , and SF-M ( -62 ) groups ( p < 0.001 ) . Change in total energy intake ( including solid foods ) and infant weight and length gain did not differ significantly between groups . Weight and length gain from 4 - 6 months were comparable to those of breastfed infants in an affluent USA population . The results indicate that breastfed infants self-regulate their total energy intake when other foods are introduced . As a result , there is no advantage in introducing complementary foods before 6 months in this population , whereas there may be disadvantages if there is increased exposure to contaminated weaning foods BACKGROUND Results on growth and nutrient intake in infants in the second half of infancy fed human milk or formulas with varying protein concentrations in combination with supplementary foods  have not previously been reported . METHODS Seventy-one healthy infants were studied from 3 to 12 months of age . They were exclusively breast-fed until 3 months and were then r and omly assigned to one of three feeding groups , F13 , F15 , or F18 , indicating formulas with 13 , 15 or 18 g/l of protein , respectively . Formula was gradually introduced when breast-feeding was terminated . Infants fed  breast milk only were included in the breast-fed group , and those with breast milk and formula were included in the mixed-fed group . The same supplementary foods were provided to all infants . RESULTS There were no differences in growth between the feeding groups . Total protein intake exceeded minimum recommendations in all groups at all ages and was higher at 6 months in F18 than in F13 ( 2.3 vs. 1.9 g/kg per day ; p < 0.01 ) , whereas formula protein intake was higher at all ages in F18 compared with F13 . Intake of protein from supplementary foods increased , but that from formula decreased between 6 and 12 months in all groups . CONCLUSIONS Intake of breast milk or infant formula with 13 g/l of protein along with high-protein supplementary foods provided enough protein with no adverse effect on growth . Infants fed formulas with higher protein concentrations had similar growth , despite higher intakes of formula protein OBJECTIVE To compare the growth and illness pattern of infants who were exclusively breast fed for six months with those of infants commenced on complementary feeding before the age of six months and ascertain reasons for the early introduction of complementary feeding . DESIGN A comparative prospect i ve study . SETTING Urban Comprehensive Health Centre ( UCHC ) , Obafemi Awolowo University Teaching Hospitals Complex , Ile-Ife . SUBJECTS Three hundred and fifty-two mothers and their normal birth weight babies , weighing 2.500 kg or more , and aged less than 14 days were serially recruited into the study . MAIN OUTCOME MEASURES Mean/median monthly weights in the first six months of life , history/outpatient presentation for illnesses . RESULTS Of the 352 mother-infant pairs recruited into the study , 345 ( 98 % ) were successfully followed up for the first six months of life . At six months , 264 ( 76.5 % ) were exclusively breast-fed , 45 ( 13.1 % ) were started on complementary feeding , between the ages of four and six months while 36 ( 10.4 % ) commenced complementary feeding before the age of four months . Infants who were exclusively breast-fed for six months had median weights above the 50th percentiles of the WHO/NCHS reference that is currently used in the national " road to health " ( growth monitoring ) cards . Furthermore , the mean weight of these babies at age six months was above those of babies who started complementary foods before six months . They also reported fewer symptoms and had fewer illness episodes ( 0.1 episodes per child ) compared to those who started complementary feeding before six months . Infants who commenced complementary feeding before four months reported more symptoms and had more illness episodes ( 1.4 episodes per child ) compared to those that commenced complementary feeding between four and six months ( 1.2 episodes per child ) . Common symptoms/illnesses seen or reported during the study among the groups were fever , diarrhoea and cough . Reasons given for early introduction of complementary foods include insufficient breast milk , thirst and convenience . CONCLUSION It is concluded that exclusive breast-feeding supported adequate growth during the first six months of life for most of the infants studied . Early introduction of complementary foods did not provide any advantages in terms of weight gain in our environment , it was frequently associated with illness episodes and growth faltering . Many mothers however require support , encouragement and access to health care providers to breastfeed exclusively for the first six months of life The hypothesis that breast-feeding can provide protection against the development of  insulindependent diabetes mellitus ( IDDM )  and would , therefore , be less common among subjects with IDDM was tested with a retrospective design . Cases ( n = 268 ) were selected from the Colorado IDDM Registry and the Barbara Davis Center for Childhood Diabetes ( Denver , CO ) . Two control groups were recruited , one from physicians ' practice s throughout Colorado ( n = 291 ) and the second through r and om-digit dialing from the Denver area ( n = 188 ) . Cases were less likely to have been breast-fed than controls after adjustment for birth year , maternal age , maternal education , family income , race , and sex [ adjusted odds ratio ( OR ) = 0.70 ; 95 % confidence interval ( Cl ) = 0.50–0.97 ] . This finding was consistent for both control groups and by birth-year intervals . A greater decrease in risk of IDDM was seen among subjects who had been breast-fed to an older age ( for breast-feeding duration of ≥12 mo , adjusted OR = 0.54 , 95 % Cl = 0.27–1.08 ) . The amount of IDDM that might be explained by breast-feeding habits ( population percentage attributable risk ) ranged from 2 to 26 % , varying according to the breast-feeding prevalence reported in other studies . Replication of this work in different population s , controlled for the strong secular trends in breast-feeding habits , is critical before the hypothesis of protection is accepted The influence of reproductive factors on bone mass at six skeletal sites was assessed in an age-stratified r and om sample of white women residing in Rochester , Minnesota . After age-adjustment , whether or not women had ever breastfed , total duration of breastfeeding and duration of breastfeeding per child were not associated with reduced bone mineral , but breastfeeding for more than 8 months was associated with greater bone mineral at some sites . There were no consistent effects on bone mineral , after adjusting for age , of gravidity or parity , age at menarche , age at first delivery , use of oral contraceptives or estrogen replacement therapy , various sex hormones , nor any of the other reproductive factors assessed . There was a strong protective effect of obesity , which was also correlated with a number of the reproductive variables . While animal studies suggest that pregnancy and lactation may be associated with calcium loss from the skeleton , these data indicate that such factors have little long-term impact on bone mass in humans and little potential for identifying women at high risk of osteoporosis later in life OBJECTIVES To evaluate the impact of introducing complementary foods to exclusively breast-fed infants at 4 vs 6 months on growth from 6 to 12 months , and to compare growth patterns of Honduran infants with those of breast-fed infants in the United States . DESIGN R and omized intervention trial from 4 to 6 months and longitudinal study of infants from birth to 12 months . SETTING Low-income communities in San Pedro Sula , Honduras . SUBJECTS Primiparous , breast-feeding mothers and their infants ( n = 141 ) recruited from public maternity hospitals . INTERVENTION Infants were r and omly assigned to exclusive breast-feeding to 6 months , or exclusive breast-feeding with addition of hygienically prepared , nutritionally adequate complementary foods at 4 months , with or without maintenance of baseline breast-feeding frequency . After 6 months , mothers continued to breast-feed and also fed their infants home-prepared foods after receiving instruction in appropriate feeding practice s. OUTCOME MEASURES Infant weight was measured monthly during the first year of life and infant length monthly from 4 to 12 months . STATISTICAL ANALYSIS Growth parameters were compared between the Honduran and US cohorts using multiple-regression and repeated- measures analysis of variance . Stepwise multiple regression was used to identify determinants of infant growth . RESULTS There were no differences in growth patterns by intervention group . Mean birth weight of the Honduran infants was significantly less than that of a cohort of breast-fed infants in an affluent US population ( n = 46 ) ( 2889 + /- 482 vs 3611 + /- 509 g ) , but the Honduran infants exhibited rapid catch up in weight in the first few months of life , and the cohorts were similar in weight by 3 months . Mean weight and length gain were similar to those of the US cohort from 4 to 9 months but were lower from 9 to 12 months . Mean length for age was significantly less than that of the US cohort from 4 to 12 months ; this was attributable to the difference in maternal height ( 12 cm shorter in Honduras on average ) . Within the Honduran cohort , growth velocity of low birth weight infants ( < 2500 g ; n = 28 ) was similar to that of their normal birth weight peers ; thus , the former subgroup remained smaller than the latter throughout the first year of life . CONCLUSIONS In poor population s , when breast-feeding is exclusive for the first 4 to 6 months , continues from 6 to 12 months , and is accompanied by generally adequate complementary foods , faltering in weight does not occur before 9 months among infants born with birth weights of more than 2500 BACKGROUND Despite the current World Health Organization recommendation that infants be exclusively breastfed for 6 mo , this practice remains unusual in both developed and developing countries . OBJECTIVE The objective was to compare health and development outcomes at age 6.5 y in children who were exclusively breastfed for 3 mo ( EBF3 ) or for 6 mo ( EBF6 ) ;  in the  EBF3 group , the children continued partial breastfeeding for > or = 6 mo . DESIGN This was a prospect i ve cohort study nested within a large , cluster-r and omized trial of a  breastfeeding promotion intervention in the Republic of Belarus . Outcomes compared at 6.5 y included anthropometric measurements , systolic and diastolic blood pressure , intelligence quotient , teachers ' ratings of academic performance , parent- and teacher-rated behavior , atopic symptoms , allergen skin-prick tests , and dental caries . All statistical analyses were adjusted for cluster- and individual-level covariates and for clustering of outcomes within the clinics at which the children were examined . RESULTS The 2427 EBF3 and 524 EBF6 children who were followed up represented 84.7 % and 89.4 % , respectively , of those followed for the first year of life . The only significant differences observed between the 2 groups were in mean body mass index , triceps skinfold thickness , and hip circumference , all of which were higher in the EBF6 group . CONCLUSIONS We observed no demonstrable beneficial or adverse long-term effects on child health of exclusive breastfeeding for 6 mo . Higher adiposity measures in the EBF6 group probably reflect reverse causality rather than a causal effect of prolonged exclusive breastfeeding . Established benefits appear to be limited to the period of exclusive breastfeeding The New Zeal and Cot Death Study , a multicentre case-control study , was set up to identify risk factors associated with sudden infant death syndrome ( SIDS ) . In the 3 years of the study there were 485 infant deaths classified as SIDS in the study areas and 1800 infants who were r and omly selected as controls . Data were collected by parent interviews and from obstetric notes . A full set of data for this analysis was available from 356 cases and 1529 control infants . The relationship between length of any breastfeeding and SIDS was examined : 92 % of the controls were initially breastfed compared to 86 % of the cases . As time went by , cases stopped breastfeeding sooner than controls : by 13 weeks , 67 % controls were breastfed versus 49 % cases . A reduced risk for SIDS in breastfed infants persisted during the first 6 months after controlling for confounding demographic , maternal and infant factors . Infants exclusively breastfed ' at discharge from the obstetric hospital ' ( odds ratio [ OR ] = 0.52 , 95 % confidence interval ( CI ) : 0.35 - 0.71 ) and during the last 2 days ( OR = 0.65 , 95 % CI : 0.46 - 0.91 ) had a significantly lower risk of SIDS than infants not breastfed after controlling for potential confounders . We have shown a substantial association of breastfeeding with a lowered risk for SIDS . This supports the need for more positive promotion and active community support to further enhance the level and length of exclusive breastfeeding The aim of this study was to examine the nature of the association between breastfeeding , complementary feeding and growth in a r and om sample of infants from Denmark , where the prevalence of breastfeeding is high . A semiquantitative food frequency question naire and a question naire on  breastfeeding duration and on weight and length measurements taken at the infant welfare visit at 5 and 10 months were sent to 590 families with 10‐month‐old infants . A total of 339 infants with complete growth data were included in the analyses . When controlling for mid‐parental height and birth weight infants breastfed for ≥ 7 months gained 198 g less in weight ( p < 0:01 ) and 7 mm less in length ( p < 0:01 ) during the period from 5 to 10 months than infants breastfed for < 7 months . Controlling for these effects , the 10 % of the sample with the highest protein intake ( i.e. ≥16 energy percentage ) gained 262 g more than those with a lower protein intake ( p= 0:03 ) . Infants breastfed for ≥ 7 months received significantly less cow 's milk ( p < 0:01 ) , and fewer meat‐containing dishes ( p < 0:05 ) and sweets or cakes ( p < 0:01 ) , which may partly explain the effect of breastfeeding . The long‐term consequences of this moderate difference in growth velocity are unknown and the findings should not be used to advocate against breastfeeding during late infancy CONTEXT Current evidence that breastfeeding is beneficial for infant and child health is based exclusively on observational studies . Potential sources of bias in such studies have led to doubts about the magnitude of these health benefits in industrialized countries . OBJECTIVE To assess the effects of breastfeeding promotion on breastfeeding duration and exclusivity and gastrointestinal and respiratory infection and atopic eczema among infants . DESIGN The Promotion of Breastfeeding Intervention Trial ( PROBIT ) , a cluster-r and omized trial conducted June 1996-December 1997 with a 1-year follow-up . SETTING Thirty-one maternity hospitals and polyclinics in the Republic of Belarus . PARTICIPANTS A total of 17 046 mother-infant pairs consisting of full-term singleton infants weighing at least 2500 g and their healthy mothers who intended to breastfeed , 16491 ( 96.7 % ) of which completed the entire 12 months of follow-up . INTERVENTIONS Sites were r and omly assigned to receive an experimental intervention ( n = 16 ) modeled on the Baby-Friendly Hospital Initiative of the World Health Organization and United Nations Children 's Fund , which emphasizes health care worker assistance with initiating and maintaining breastfeeding and lactation and postnatal breastfeeding support , or a control intervention ( n = 15 ) of continuing usual infant feeding practice s and policies . MAIN OUTCOME MEASURES Duration of any breastfeeding , prevalence of predominant and exclusive breastfeeding at 3 and 6 months of life and occurrence of 1 or more episodes of gastrointestinal tract infection , 2 or more episodes of respiratory tract infection , and atopic eczema during the first 12 months of life , compared between the intervention and control groups . RESULTS Infants from the intervention sites were significantly more likely than control infants to be breastfed to any degree at 12 months ( 19.7 % vs 11.4 % ; adjusted odds ratio [ OR ] , 0.47 ; 95 % confidence interval [ CI ] , 0.32 - 0.69 ) , were more likely to be exclusively breastfed at 3 months ( 43.3 % vs 6.4 % ; P<.001 ) and at 6 months ( 7.9 % vs 0.6 % ; P = .01 ) , and had a significant reduction in the risk of 1 or more gastrointestinal tract infections ( 9.1 % vs 13.2 % ; adjusted OR , 0.60 ; 95 % CI , 0.40 - 0.91 ) and of atopic eczema ( 3.3 % vs 6.3 % ; adjusted OR , 0.54 ; 95 % CI , 0.31 - 0.95 ) , but no significant reduction in respiratory tract infection ( intervention group , 39.2 % ; control group , 39.4 % ; adjusted OR , 0.87 ; 95 % CI , 0.59 - 1.28 ) . CONCLUSIONS Our experimental intervention increased the duration and degree ( exclusivity ) of breastfeeding and decreased the risk of gastrointestinal tract infection and atopic eczema in the first year of life . These results provide a solid scientific underpinning for future interventions to promote breastfeeding Infants who receive prolonged and exclusive breastfeeding  grow more slowly during the first year of life than those who do not . However , infant feeding and growth are dynamic processes in which feeding may affect growth , and prior growth and size may also influence subsequent feeding decisions . The authors carried out an observational analysis of 17,046 Belarusian infants who were recruited between June 1996 and December 1997 and who participated in a cluster-r and omized trial of a breastfeeding promotion intervention .  To assess the effects of infant size on subsequent feeding , the authors restricted the analysis to infants breastfed ( or exclusively breastfed ) at the beginning of each follow-up interval and examined associations between weight or length at the beginning of the interval and weaning or discontinuation of exclusive breastfeeding by the end of the interval . Smaller size ( especially weight for age ) was strongly and statistically significantly associated with increased risks of subsequent weaning and of discontinuing exclusive breastfeeding ( adjusted odds ratios = 1.2 - 1.6 ) , especially between 2 and 6 months , even after adjusment for potential confounding factors and clustered measurement . The authors speculate that similar dynamic processes involving infant crying , other signs of hunger , and supplementation/weaning undermine causal inferences about the " effect " of prolonged and exclusive breastfeeding on slower infant growth A population -based case-control study of breast cancer with a focus on premenopausal women under 45 years of age , conducted in three geographic regions of the United States , enabled the evaluation of risk in relation to varying breastfeeding practice s. Among premenopausal parous women ( 1,211 cases , 1,120 r and om-digit-dialing controls ) , a history of breastfeeding for two or more weeks was associated with a relative risk ( RR ) of 0.87 ( 95 percent confidence interval [CI]=0.7–1.0 ) . This relationship was not altered substantially by removing from the reference group women who had problems with breastfeeding in the first two weeks , including those with insufficient milk production . Risk was not related substantially to number of children breastfed or length of breastfeeding , although a relatively low risk was observed among those breastfeeding for the longest duration examined ( RR=0.67 , CI=0.4–1.1 for an average period per child of 72 or more weeks ) . Women who began to breastfeed at a young age ( < 22 years ) experienced the greatest reduction in risk , but other timing parameters ( e.g. , interval since first or last breastfeeding ) were not predictive of risk . Risks were not modified substantially by age or menopause status , although the number of menopausal subjects examined was limited . Use of medications to stop breast milk was unrelated to risk ( RR=1.04 ) . The results of this study do not support the notion that breastfeeding substantially reduces breast cancer risk ; however , this may reflect the fact that most of our study subjects breastfed only for limited periods of time ( average breastfeeding per child of 30 weeks ) . Further studies are needed to clarify the relationship of breastfeeding to breast cancer risk , and to determine possible etiologic mechanisms underlying any observed associations Abstract The relationship between growth and the breast-milk plus complementary food intake of a group of British babies has been studied prospect ively up to 8 months . From the data the human milk needs of  solely breast-fed children to grow along the 5th , 50th , and 95th Gentile of the NCHS st and ard have been predicted using multiple regression analysis . The values obtained are substantially lower than previous estimates and they may form a more practical guideline for the evaluation of lactational adequacy within a community . Individual variation is important . It is futile to identify a single age when breast-feeding becomes inadequate as the sole source of food The need for r and omization as a means of controlling confounders is accentuated in the study of intended effects ( efficacy ) as compared with unintended ones ( toxicity ) . The basic reason is that the indication for intervention is inherently a confounder in the study of efficacy but not of toxicity , whereas contraindications represent only a minor confounder even in toxicity research . Moreover , control of the indication in non-experimental terms is commonly infeasible owing to the complexity and subtlety of the indication . BACKGROUND Available evidence suggests that prolonged and exclusive breastfeeding is associated with lower infant weight and length by 6 to 12 months of age . This evidence , however , is based on observational studies , which are unable to separate the effects of feeding mode per se from selection bias , reverse causality , and the confounding effects of maternal attitudinal factors . DESIGN / METHODS A cluster-r and omized trial in the Republic of Belarus of a breastfeeding promotion intervention modeled on the World Health Organization (WHO)/UNICEF Baby-Friendly Hospital Initiative versus control ( then current ) infant feeding practice s. Healthy , full-term , singleton breastfed infants ( n = 17 046 ) weighing > or = 2500 g were enrolled soon after birth and followed up at 1 , 2 , 3 , 6 , 9 , and 12 months old for measurements of weight , length , and head circumference . Data were analyzed according to intention-to-treat , while accounting for within-cluster correlation . To assess the potential for bias in observational studies of breastfeeding , we also analyzed our data as if we had conducted an observational study by ignoring treatment , combining the 2 r and omized groups , and comparing 1378 infants weaned in the first month and those breastfed for the full 12 months of follow-up with either > or =3 months ( n = 1271 ) or > or = 6 months ( n = 251 ) of exclusive breastfeeding . RESULTS Infants from the experimental sites were significantly more likely to be breastfed ( to any degree ) at 3 , 6 , 9 , and 12 months and were far more likely to be exclusively breastfed at 3 months ( 43.3 % vs 6.4 % ) . Mean birth weight was nearly identical in the 2 groups ( 3448 g , experimental ; 3446 g , control ) . Mean weight was significantly higher in the experimental group by 1 month of age ( 4341 vs 4280 g ) . The difference increased through 3 months ( 6153 g vs 6047 g ) , declined slowly thereafter , and disappeared by 12 months ( 10564 g vs 10571 g ) . Analysis by z scores confirmed that infants in both groups gained more weight than the WHO/Centers for Disease Control and Prevention reference , with no evidence of undernutrition in the control group . Length followed a similar pattern . In the observational analyses , infants weaned in the first month were slightly lighter and shorter at birth and their weight-for-age and length-for-age z scores declined by 1 month , but they caught up to both experimental and the other observational groups by 6 months and were heavier and longer by 12 months . Among infants in the 2 prolonged and exclusive breastfeeding groups , weight-for-age z scores fell slightly between 3 and 12 months ; length-for-age fell below the reference by 6 months with catch-up to the reference by 12 months . Head circumference showed no significant differences at any age between the 2 trial groups or among the observational groups . CONCLUSIONS Our data , the first in humans based on a r and omized experiment , suggest that prolonged and exclusive breastfeeding may actually accelerate weight and length gain in the first few months , with no detectable deficit by 12 months old . These results add support to current WHO and UNICEF feeding recommendations . Our observational analysis showing faster weight and length gains with early weaning and slower gains with prolonged and exclusive breastfeeding may reflect unmeasured confounding differences or a true biological effect of formula feeding It has been argued that the growth rate of exclusively breast-fed infants may be limited by their protein intake . This issue was examined using data from an intervention study in Honduras in which infants were r and omly assigned to be  exclusively breast-fed for the first 6 mo ( EBF ; n = 50 ) , or to receive preprepared solid foods ( including egg yolk ) in addition to breast milk beginning at 4 mo ( n = 91 ) . Neither weight gain nor length gain from 4 to 6 mo differed between groups despite a 20 % higher protein intake ( as well as significantly higher intakes of iron , zinc , calcium , vitamin A , and riboflavine ) in the latter group . The 20 infants with the highest protein intakes in that group were matched to 20 EBF infants on the basis of energy intake ; protein intake was 1.46 ± 0.09 versus 1.10 ± 0.17 g/kg/d , respectively ( p < 0.001 ) , but growth rate did not differ between groups . Similarly , the 20 infants with the lowest protein intakes in the EBF group were matched ( by energy intake ) to 20 infants given solid foods ; protein intake was very low in the former compared with the latter ( 0.81 ± 0.13 versus 1.04 ± 0.20 g/kg/d;p < 0.001 ) , yet there was still no difference in growth . Infant morbidity was relatively low and did not influence the results . These analyses indicate that protein intake is not likely to be a limiting factor with regard to growth of breast-fed infants from 4 to 6 mo of age
BACKGROUND Although the health benefits of breastfeeding are widely acknowledged , opinions and recommendations are strongly divided on the optimal duration of exclusive breastfeeding .
Since 2001 , the World Health Organization has recommended exclusive breastfeeding for six months .
Much of the recent debate in developed countries has centred on the micronutrient adequacy , as well as the existence and magnitude of health benefits , of this practice .
OBJECTIVES To assess the effects on child health , growth , and development , and on maternal health , of  exclusive breastfeeding  for six months versus exclusive breastfeeding for three to four months with mixed breastfeeding ( introduction of complementary liquid or solid foods with continued breastfeeding ) thereafter through six months .