Effects of exclusive breastfeeding for four versus six months on maternal nutritional status and infant motor development: results of two randomized trials in Honduras. Effects of age of introduction of complementary foods on iron status of breast-fed infants in Honduras. 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. 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. 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. Influence of breastfeeding and complementary food on growth between 5 and 10 months Do Exclusively Breast-Fed Infants Require Extra Protein?
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 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 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 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 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 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 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 .
Much of the debate has centered on the so-called ' weanling 's dilemma ' in developing countries : the choice between the known protective effect of exclusive breastfeeding against infectious morbidity and the ( theoretical ) insufficiency of breast milk alone to satisfy the infant 's energy and micronutrient requirements beyond four months of age .
The debate over whether to recommend exclusive breastfeeding for four to six months versus ' about six months ' has recently become heated and acrimonious .
OBJECTIVES : The primary objective of this review was 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 .
A secondary objective was to assess the child and maternal health effects of prolonged ( greater than six months ) exclusive breastfeeding versus exclusive breastfeeding for six months followed by mixed breastfeeding thereafter .