Exclusive breast-feeding for 6 months, with iron supplementation, maintains adequate micronutrient status among term, low-birthweight, breast-fed infants in Honduras

There is little information on the risk of micronutrient deficiencies during the period of exclusive breast-feeding. We evaluated this among term, low-birthweight (LBW; 1500-2500 g) infants in Honduras. Mother-infant pairs were recruited in the hospital and assisted with exclusive breast-feeding during the first 4 mo. At 4 mo, infants were randomly assigned to either continue exclusive breast-feeding to 6 mo (EBF; n = 59) or be given iron-fortified complementary foods (rice, chicken, fruits, and vegetables) from 4 to 6 mo while continuing to breast-feed (SF, n = 60). Blood samples were collected at 2, 4, and 6 mo and analyzed for hemoglobin (Hb), hematocrit, plasma ferritin, % transferrin saturation, vitamin A, vitamin B-12, folate, zinc, and erythrocyte folate. Infants with Hb < 100 g/L at 2 or 4 mo were given medicinal iron supplements for 2 mo; the proportion administered iron drops did not differ significantly between groups. There was no significant effect of complementary foods on indices of vitamin A, B-12, folate, or zinc status. Among infants not given medicinal iron at 4-6 mo, iron status was higher in the SF group than the EBF group. In those given medicinal iron at 4-6 mo, iron status was higher in the EBF group, suggesting that complementary foods interfered with iron utilization. About half of the infants were anemic by 2 mo, before the age when complementary foods would be recommended. This supports the recommendation that LBW infants should receive iron supplementation in early infancy. Given that infants given iron supplements did not benefit from complementary foods at 4-6 mo, we conclude that exclusive breast-feeding for 6 mo (with iron supplementation) can be recommended for term, LBW infants.     

Effects of exclusive breastfeeding for four versus six months on maternal nutritional status and infant motor development: results of two randomized trials in Honduras

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 randomly 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.     

Iron absorption in breast-fed infants: effects of age,iron status,iron supplements,and complementary foods

BACKGROUND: Iron supplements are often recommended for older breast-fed infants, but little is known about factors affecting iron absorption from human milk or supplements. OBJECTIVE: We investigated the effects of age, iron status, and iron intake on iron absorption in healthy, term, breast-fed infants. DESIGN: Twenty-five infants were randomly assigned to receive either 1) iron supplements (1 mg x kg(-1) x d(-1)) from 4 to 9 mo of age, 2) placebo from 4 to 6 mo and iron supplements from 6 to 9 mo, or 3) placebo from 4 to 9 mo. Infants were exclusively breast-fed to 6 mo and partially breast-fed to 9 mo of age. Iron absorption was assessed by giving (58)Fe with mother's milk at 6 and 9 mo. Blood samples were obtained at 4, 6, and 9 mo, and complementary food intake was recorded at 9 mo. RESULTS: At 6 mo, mean (+/-SD) fractional iron absorption from human milk was relatively low (16.4 +/- 11.4%), with no significant difference between iron-supplemented and unsupplemented infants. At 9 mo, iron absorption from human milk remained low in iron-supplemented infants (16.9 +/- 9.3%) but was higher (P = 0.01) in unsupplemented infants (36.7 +/- 18.9%). Unexpectedly, iron absorption at 9 mo was not correlated with iron status but was significantly correlated with intake of dietary iron, including supplemental iron. CONCLUSIONS: Changes in the regulation of iron absorption between 6 and 9 mo enhance the infant's ability to adapt to a low-iron diet and provide a mechanism by which some, but not all, infants avoid iron deficiency despite low iron intakes in late infancy.     

Breast milk and energy intake in exclusively, predominantly, and partially breast-fed infants

OBJECTIVE: To investigate the extent to which breast milk is replaced by intake of other liquids or foods, and to estimate energy intake of infants defined as exclusively (EBF), predominantly (PBF) and partially breast-fed (PartBF). DESIGN: Cross-sectional. SETTING: Community-based study in urban Pelotas, Southern Brazil. SUBJECTS: A total of 70 infants aged 4 months recruited at birth. MAIN OUTCOME MEASURES: Breast milk intake measured using a "dose-to-the-mother" deuterium-oxide turnover method; feeding pattern and macronutrient intake assessed using a frequency questionnaire. RESULTS: Adjusted mean breast milk intakes were not different between EBF and PBF (EBF, 806 g/day vs PBF, 778 g/day, P=0.59). The difference between EBF and PartBF was significant (PartBF, 603 g/day, P=0.004). Mean intakes of water from supplements were 10 g/day (EBF), 134 g/day (PBF) and 395 g/day (PartBF). Compared to EBF these differences were significant (EBF vs PBF, P=0.005; EBF vs PartBF, P<0.001).The energy intake of infants receiving cow or formula milk (BF+CM/FM) in addition to breast milk tended to be 20% higher than the energy intake of EBF infants (EBF, 347 kJ/kg/day vs BF+CM/FM, 418 kJ/kg/day, P=0.11). CONCLUSIONS: There was no evidence that breast milk was replaced by water, tea or juice in PBF compared to EBF infants. The energy intake in BF+CM/FM infants tended to be 20% above the latest recommendations (1996) for breast-fed and 9% above those for formula-fed infants. If high intakes are maintained, this may result in obesity later in life. SPONSORSHIP: International Atomic Energy Agency through RC 10981/R1.     

Lactation counseling increases breast-feeding duration but not breast milk intake as measured by isotopic methods

The importance of exclusive breast-feeding in the first 6 mo of life is widely recognized, but most mothers still do not reach this goal. Several studies have shown that face-to-face lactation counseling is effective in increasing not only exclusive breast-feeding rates but also the total duration of breast-feeding. However, it is unclear whether counseling could increase breast milk intake. The purpose of this study was to evaluate the effect of lactation counseling on breast milk intake, assessed through the deuterium dilution method. This was a blind, randomized intervention trial of lactation counseling in a sample of 188 babies born in Pelotas, selected with the same criteria used for the WHO Multicentre Growth Reference Study (MGRS). The main outcomes were breast-feeding pattern and duration for all infants as well as breast milk intake for a subsample of 68 infants at the age of 4 mo. Mothers in the control group were almost twice as likely to stop breast-feeding by 4 mo as those in the intervention group (prevalence ratio 1.85; P = 0.04). Cox regression confirmed that the velocity of weaning was twice as high in the control group. Breast milk and total water intakes did not differ between the groups. The deuterium dilution technique proved to be a practical means of assessing breast milk intake. Lactation counseling reduced early weaning, but breast milk intake at 4 mo was not affected.     

Breast milk intake is not reduced more by the introduction of energy dense complementary food than by typical infant porridge

The effect of different energy densities of complementary foods on breast milk consumption is not well understood. In this study, we tested the hypothesis that provision of fortified spread (FS), a micronutrient fortified, energy-dense (22 kJ/g), ready-to-use food, to Malawian infants would not decrease their breast milk intake more than a traditional corn + soy blended flour (CSB). Forty-four healthy 6-mo-old infant and mother pairs were enrolled in a prospective, parallel group, investigator-blinded, randomized controlled complementary feeding trial. Infants were randomized to receive 25 g/d of FS, 50 g/d of FS, or 72 g/d of CSB. The primary outcome was the difference in breast milk intake after 1 mo of complementary feeding as measured by the dose-to-mother deuterium oxide dilution technique. Outcomes were compared using repeated measures ANOVA. A total of 41 mother-infant pairs completed the study. At enrollment, 88% of the infants had received corn porridge. At baseline, the infants consumed 129 +/- 18 g.kg body wt(-1) x d(-1) (mean +/- SD) of breast milk. After 1 mo of complementary feeding with 25 g/d FS, 50 g/d FS, or 72 g/d CSB, their breast milk consumption was 115 +/- 18 g.kg body wt(-1) x d(-1), a significant reduction; however, the effects of the complementary foods did not differ from one another (F-value model = 4.33, P = 0.0008 for effect of time and P = 0.69 for effect of type of food). The results suggest that complementary feeding of Malawian infants with FS has the same effect on their breast milk intake as complementary feeding with traditional CSB porridge.     

Proposed vitamin a fortification levels

Fortified complementary foods could be effective in preventing and controlling vitamin A and other common nutritional deficiencies in young children. Milk from well-nourished women is an excellent source of vitamin A. However, in Latin America many children are weaned prematurely and must receive the entire requirement of vitamin A from food. This paper proposes vitamin A fortification levels for foods targeted for children aged 6-23 mo to meet the existing intake gap among both breast-fed and weaned infants and young children. Estimates assume a nonsignificant contribution of common complementary foods and average levels of human milk intake by breast-fed infants and children. The estimated vitamin A gap for breast-fed infants aged 6-11 mo amounts to 63-92 microg RE [16-23% of recommended daily intake (RDI)] and for breast-fed children reaches 125 microg RE (31% of RDI). Weaned infants and children would have to fully meet the RDI (400 microg RE) from complementary foods. A fortified complementary food with 500 mg RE/100 g of dry product provided daily in a single ration of 40 g would meet 50% of the gap for weaned infants aged 6-11 mo and would raise the total intake above RDI for breast-fed infants aged 6-8 mo (125%) and 9-11 mo (127%). The same fortified food given in a daily ration of 60 mg would meet most of the gap (75%) for weaned children aged 12-23 mo and would increase total intake of breast-fed children aged 12-23 mo well above the RDI (144%), with no risk of exceeding established upper tolerable intake levels.     

Effects of energy density and feeding frequency of complementary foods on total daily energy intakes and consumption of breast milk by healthy breastfed Bangladeshi children

BACKGROUND: Information is needed on the minimum energy density and feeding frequency of complementary foods that can provide adequate energy intakes (EIs) for healthy breastfed children. OBJECTIVES: The objectives of the study were to evaluate the effects of various energy densities and feeding frequencies of complementary foods on EI from these foods, breast milk consumption, and total EI from both sources. DESIGN: During 9 separate, randomly ordered dietary periods lasting 3-6 d each, we measured intakes of food and breast milk by 18 healthy breastfed children 8-11 mo of age who, 3, 4, or 5 times/d, were fed porridge with a coded energy density of 0.5, 1.0, or 1.5 kcal/g. Food intake was measured by weighing the feeding bowl before and after meals, and breast milk intake was measured by test weighing. RESULTS: The mean amounts of complementary foods consumed were inversely related to their energy density and positively related to the number of meals/d (P < 0.001 for both); EIs from foods were positively related to both factors. Breast milk intake decreased slightly but progressively, with greater energy density and feeding frequency of complementary foods; total EIs (kcal/d) increased in relation to both factors (P < 0.001 for both). CONCLUSIONS: The energy density and feeding frequency of complementary foods affect infants' total daily EI and breast milk consumption. Recommendations can be developed for the appropriate combinations of these dietary factors that are compatible with adequate EI, although longer-term effects of complementary feeding practices on breast milk intake and breastfeeding duration need further community-based studies.     

Food choices to meet nutritional needs of breast-fed infants and toddlers on mixed diets

The primary focus of this review is considerations for complementary feedings to meet micronutrient needs of infants aged 6-24 mo who are continuing with breast-feeding and minimal or no formula. The World Health Organization recommends initiation of complementary feeding to breast-fed infants at approximately 6 mo of age. Whether complementary foods will meet nutrient needs will depend on the types of food selected. One criterion for the selection of complementary foods is that they be rich sources of zinc and iron because both of these essential micronutrients are critical for normal growth and development, and requirements are not met by exclusive breast-feeding after approximately 6 mo. For an exclusively breast-fed 7-mo-old infant, human milk provides approximately 0.5 mg of zinc, and a little over half of that is absorbed. Adding some cereal can increase zinc intake modestly but will fall short of providing the estimated physiologic requirement because adaptive mechanisms are inadequate to compensate for moderately low zinc intake. Maize, wheat, rice, and roots are also relatively low in zinc and have the added factor of a high phytate-to-zinc molar ratio, which makes the zinc less bioavailable. Meats and liver have greater zinc and iron concentrations than unfortified plant foods and have been shown to have good acceptance by 7-mo-old infants. In contrast to current practices in both developed and developing countries, meats should be considered as an early complementary food for breast-fed infants to provide essential micronutrients.     

Risk of infant anemia is associated with exclusive breast-feeding and maternal anemia in a Mexican cohort

The WHO recommends exclusive breast-feeding (EBF) for the first 6 mo of life to decrease the burden of infectious disease. However, some are concerned about the effect of EBF >6 mo on iron status of children in developing countries in which anemia is prevalent. This study examines the risk of anemia in relation to the duration of EBF and maternal anemia in a birth cohort studied between March 1998 and April 2003. All infant birth weights were >or=2.2 kg. All mothers received home-based peer counseling to promote EBF. Infant feeding data were collected weekly. Nurses measured hemoglobin (Hb) values every 3 mo. Hb was measured in 183 infants at 9 mo of age. Anemia at 9 mo was defined as a Hb value <100 g/L. EBF was defined by WHO criteria and ranged in duration from 0 to 31 wk. At 9 mo, Hb (mean +/- SEM) was 114 +/- 0.9 g/L; 23 children (12.5%) had Hb levels <100 g/L. EBF >6 mo, but not EBF 4-6 mo, was associated with increased risk of infant anemia compared with EBF <4 mo (odds ratio=18.4, 95% CI=1.9, 174.0). Maternal anemia was independently (P=0.03) associated with a 3-fold increased risk of infant anemia. These associations were not explained by confounding with other maternal or infant factors. By linear regression, a lower infant Hb at 9 mo was associated with increased EBF duration among mothers who had a history of anemia (beta=-0.07, P=0.003), but not among mothers with no history of anemia. Infants who are exclusively breast-fed for >6 mo in developing countries may be at increased risk of anemia, especially among mothers with a poor iron status; greater attention to this issue is warranted.     

Fortified complementary foods with or without alpha-amylase treatment increase hemoglobin but do not reduce breast milk intake of 9-mo-old Zambian infants

BACKGROUND: Malnutrition in late infancy in developing countries may result from poor-quality complementary foods that displace breast milk. OBJECTIVE: The objective of the study was to assess the effects of fortified complementary blends of different energy densities on growth, hemoglobin concentrations, and breast milk intake of 9-mo-old Zambian infants. DESIGN: Infants were randomly assigned at 6 mo of age to receive for 3 mo a fortified blend of maize, beans, bambaranuts, and groundnuts [Chilenje Baby Mix (CBM); energy density: 68 kcal/100 g; n = 37] or a similar blend with alpha-amylase (CBMA; energy density: 106 kcal/100 g; n = 44). Cross-sectional data were obtained at 9 mo for a control group of infants (n = 69) not given the diets. Breast milk intake was measured by using the dose-to-the-mother deuterium dilution technique. RESULTS: No differences in weight or length z scores, all of which were within normal ranges, were seen between groups at 9 mo. Percentage fat mass was significantly (P = 0.01) greater in the infants in both the CBM (23.2 +/- 2.7%) and CBMA (23.4 +/- 2.5%) groups than in the control group (21.6 +/- 2.6%). Hemoglobin concentrations were significantly (P = 0.03) greater in both intervention groups (CBM group: 104 +/- 12 g/L: CBMA group: 103 +/- 12 g/L) than in the control group (98 +/- 14 g/L). Breast milk intake was not significantly (P = 0.87) different between groups (CBM group: 614 +/- 271 g/d; CBMA group: 635 +/- 193 g/d; control group: 653 +/- 221 g/d). CONCLUSIONS: The study foods improved hemoglobin concentrations without reducing breast milk intake and may be used to improve the nutritional status of infants in developing countries.     

Low nutrient intakes among infants in rural Bangladesh are attributable to low intake and micronutrient density of complementary foods

We assessed the adequacy of nutrient intakes of 135 rural Bangladeshi breast-fed infants 6-12 mo of age and examined nutritional trade-offs due to possible displacement of breast milk by complementary foods. Observers completed 12-h daytime measurements of breast milk and complementary food intakes; data for the previous 12 h were obtained from maternal recall, yielding estimates of total 24-h intakes. On average, infants were mildly wasted (mean +/- SD weight-for-length Z-score = -0.92 +/- 0.88) and moderately stunted (length-for-age Z-score = -1.49 +/- 0.96). Total energy intakes at 6-8 and 9-12 mo were 88 and 86% of absolute energy requirements (kJ/d), 106 and 105% of requirements per kg body weight, and 97 and 94% of requirements per kg median weight-for-length, respectively. Breast milk contributed 78% of energy intake at 6-8 mo and 75% at 9-12 mo. Mean meal frequency and energy density of complementary foods were generally consistent with recommendations, but only small amounts of food were offered. Nevertheless, only 72% of the food energy offered was consumed. Total energy intake was positively correlated with meal frequency, quantity consumed per meal, and energy intake from breast milk, but not with energy density of complementary foods. Energy intake from complementary foods was inversely related to energy intake from breast milk. The diets fell short of recommended intakes for numerous vitamins and minerals. We conclude that although greater intakes of complementary foods were associated with higher total energy intake, micronutrient intake remained low due to the low micronutrient density of the complementary foods consumed and the partial displacement of breast milk.     

Growth patterns of breast-fed infants in affluent (United States) and poor (Peru) communities: implications for timing of complementary feeding.

We compared growth, dietary intake, and morbidity of infants breast-fed for > or = 12 mo from two populations: Davis, CA (n = 46) and Huascar, Peru (n = 52). When compared against WHO reference data (based primarily on formula-fed infants), Huascar infants appeared to falter as early as 3-4 mo, but when compared with Davis breast-fed infants, the curves for weight and length were very similar in girls until 10-12 mo and in boys until 6-9 mo. Thereafter, Huascar infants grew less rapidly than did Davis infants. Breast milk intake was very similar between groups, but in Huascar the amount and nutrient density of complementary foods consumed after 6 mo were lower and morbidity rates were much higher than in Davis. These results indicate that growth faltering of Huascar infants, when judged against breast-fed infants in the United States, occurs primarily after the first 6 mo of life and is not due to poor lactation performance.     

Nonbreast-fed HIV-1-exposed Burkinabe infants have low energy intake between 6 and 11 months of age despite free access to infant food aid

In a WHO-coordinated, mother-to-child HIV transmission (MTCT) prevention trial in Burkina Faso, HIV-1-infected mothers were advised to either stop breast-feeding by 6 mo or totally avoid it. Participants were provided with cereal-based, infant fortified mix (IFM) from 6 to 12 mo postpartum along with infant feeding counseling. Our objective was to describe nonbreast-fed infants' food consumption and adequacy of nutrient intake. A 1-d weighed food record and one 24-h dietary recall were performed in 68 nonbreast-fed, non-HIV-infected 6- to 11-mo-old infants. Mean food energy density and feeding frequency were satisfactory in 6-8 mo olds [0.8 ± 0.2 kcal/g (3.3 ± 0.9 kJ/g) and 7.2 ± 1.6 times/d] and in 9-11 mo olds [0.9 ± 0.2 kcal/g (3.6 ± 0.8 kJ/g) and 7.7 ± 2.1 times/d]. Median energy intake was 523 kcal [range: 82-1053 (2187 kJ, range: 345-4401)] in 6-8- and 811 kcal [range: 34-1543 (3392 kJ, range: 144-6452)] in 9-11-mo-old infants, respectively. Approximately 75% of their energy intake was provided by subsidized foods (milk that mothers obtained from support networks and IFM). One-half of the infants had intakes < 80 kcal/kg (<334 kJ/kg) on the day of the survey, mainly because IFM and milk were consumed in amounts that were too low. Thus, coverage of energy needs required a diet with sufficient amounts of both IFM and milk in these vulnerable infants. These findings argue for the development of adequate, sustainable infant fortified foods and their rapid integration into MTCT prevention services. They also lend support to the recent revision of WHO infant feeding guidance for future MTCT prevention programming that recommends breast-feeding up to 12 mo postpartum (under cover of antiretroviral prophylaxis) as the safest feeding option for infants of HIV-infected mothers.     

Poor compliance with appropriate feeding practices in children under 2 y in Mexico

We evaluated breast-feeding and complementary feeding practices in Mexico, using data from a national probabilistic survey carried out in 17,716 households, with regional and urban-rural representation. Mothers of children <2 y old (n = 3,191) reported duration of breast-feeding and the ages of usual introduction of 7 food groups. The Kaplan-Meier method was used to estimate the median time of feeding events. Practices were analyzed by categories of ethnicity, housing condition, and place of residence (geographic region and degree of urbanization). We found that 86% of infants at 1 mo and 39% at 11 mo were breast-fed, whereas 60% at 1 mo and 8% at 6 mo were exclusively breast-fed. Early introduction (<6 mo) of water, nonhuman milk, nonnutritive liquids, and fruits and vegetables was reported for all categories studied. Also, early introduction of nutritive liquids, cereals and legumes, and animal foods other than milk occurred in all categories except rural areas and the indigenous population. Late introduction of solid foods was documented in large proportions of infants in rural areas and in poor families. Poorer, unemployed, and indigenous women, and those bearing males, had a significantly higher probability of feeding their infants as recommended by the WHO. Feeding practices were unrelated to attained growth when the influence of economic and social factors was considered. Results indicate the need to implement actions for the promotion of exclusive breast-feeding during the first 6 mo and of timely introduction of complementary foods thereafter.     

Prevalent vitamin B-12 deficiency in twelve-month-old Guatemalan infants is predicted by maternal B-12 deficiency and infant diet

Approximately one-third of low-income women and children studied in Guatemala are reported to have deficient (<148 pmol/L) or marginal (148-220 pmol/L) plasma vitamin B-12 concentrations. Because vitamin B-12 deficiency can adversely affect infant development and cognitive function, the present study examined predictors of deficient plasma vitamin B-12 concentrations at the age of 12 mo. Analyses were performed on baseline data from a randomized clinical trial in 304 Guatemalan infants, 80% of whom were partially breast-fed, and their mothers. Exclusion criteria for infants included twins, severe stunting or moderate wasting, reported major health problems, severe developmental delay, hemoglobin <95 g/L, maternal age <17 y, and maternal pregnancy >3 mo. Data collected included socio-economic status, infant anthropometry, vitamin B-12 intake from complementary foods, and breast-feeding frequency reported by mothers. A complete blood count and plasma vitamin B-12, folate, ferritin, and C-reactive protein were measured. Deficient or marginal plasma vitamin B-12 concentrations were found in 49% of infants and 68% of mothers. The mean intake of maternal vitamin B-12 was 3.1 microg/d, and infants consumed 2.2 microg/d from complementary foods. In linear regression analysis, infant plasma B-12 concentration was strongly and positively associated with maternal plasma vitamin B-12 and B-12 intake from complementary foods (predominantly powdered cow's milk), and inversely associated with frequency of breast-feeding and larger household size (P < 0.0001). Vitamin B-12 supplementation of lactating women, food fortification, and education to improve infant's vitamin B-12 status are potential interventions that can improve the vitamin B-12 status of mothers and infants in this population.     

Duration of exclusive breast-feeding: introduction of complementary feeding may be necessary before 6 months of age

The WHO recommends exclusive breast-feeding for the first 6 months of life. At present, <2 % of mothers who breast-feed in the UK do so exclusively for 6 months. We propose the testable hypothesis that this is because many mothers do not provide sufficient breast milk to feed a 6-month-old baby adequately. We review recent evidence on energy requirements during infancy, and energy transfer from mother to baby, and consider the adequacy of exclusive breast-feeding to age 6 months for mothers and babies in the developed world. Evidence from our recent systematic review suggests that mean metabolisable energy intake in exclusively breast-fed infants at 6 months is 2.2-2.4 MJ/d (525-574 kcal/d), and mean energy requirement approximately 2.6-2.7 MJ/d (632-649 kcal/d), leading to a gap between the energy provided by milk and energy needs by 6 months for many babies. Our hypothesis is consistent with other evidence, and with evolutionary considerations, and we briefly review this other evidence. The hypothesis would be testable in a longitudinal study of infant energy balance using stable-isotope techniques, which are both practical and valid.     

Infant feeding patterns on Mauritius Island, 1991

The 1991 Mauritius Contraceptive Prevalence Survey (CPS) included a special module on infant feeding patterns in Mauritius. Since 1985, when a similar CPS was conducted, the incidence of breast-feeding has fallen from 86% to 72%. The duration of any breast-feeding among those breast-fed remained constant at 13.6 months. The module allowed for an assessment of the World Health Organization (WHO) breast-feeding indicators on exclusive breast-feeding, timely complementary feeding and continued breast-feeding. Only 16% of infants 0–3 months old are exclusively breast-fed; only 29% of infants 6–9 months old receive breast milk and complementary foods and only 27% of children 12–15 months are still breast-fed. These patterns of limited breast-feeding and early supplementation may signal future declines in breast-feeding for other African and Asian countries. Published by Elsevier Science Ltd     

Breast-feeding patterns in a rural village in Giza, Egypt.

In a longitudinal study of infant feeding in rural Giza, Egypt, we found that 68.8% of the recruited mothers initiated early suckling of colostrum, but only 51.2% of the infants were exclusively breast-fed in the first week. Solid foods were introduced much earlier than at the recommended age of 4 to 6 months. Sixty percent of the mothers who participated in the study considered breast-feeding plus regular or irregular complementary feeding to be exclusive breast-feeding.     

Studies in human lactation: milk volumes in lactating women during the onset of lactation and full lactation

After validation of test-weighing procedures milk volumes produced by 13 multiparous Caucasian women were followed longitudinally through the first year of lactation. All practiced exclusive breast-feeding for at least 5 mo. Milk transfer to the infant was low on days 1 and 2 and increased rapidly to 498 +/- 129 g/d (means +/- SD) on day 5 and then more slowly to 753 +/- 89 g/d during months 3-5. There was a characteristic milk volume for each mother-infant pair that was significantly related neither to milk yield on days 4-6 nor to birth weight. It was, however, strongly related to infant weight at 1 mo, suggesting that infant and/or maternal factors coming into play during the first month of life are strong determinants of subsequent milk transfer to the infant.