Optimal nutrition in infancy is the foundation of health in later life. Based on the demonstrated health benefits of human milk, breastfeeding should be the primary means of nutrition for most infants. Although many mothers experience some problems with breastfeeding, health professionals can use simple strategies to overcome most of these problems. For infants who cannot breastfeed, standard infant formulas support adequate nutrition and growth. Gastroesophageal reflux is a common feeding-related event and occurs in most infants; it is part of normal physiology and requires no intervention. Gastroesophageal reflux disease occurs in a small number of infants necessitating the use of an algorithm-based evaluation and management strategy.
Key points
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There is good evidence of the clinical benefit of breastfeeding to infants and mothers, and it should be the primary nutrition source for most infants.
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The breastfed infant is the normative model for infant growth, and the WHO growth curves should be used for all term infants.
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All standard term infant formulas are clinically equivalent and adequately support growth for the small proportion of infants who cannot breastfeed.
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Soy and other specialized formulas should be reserved for particular circumstances and conditions and should not be used routinely.
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Gastroesophageal reflux occurs in most infants and does not require intervention. Gastroesophageal reflux disease occurs in a small proportion of infants and an algorithm-based evaluation and management strategy should be used.
Neonatal nutrition
There is accumulating evidence that nutrition and growth in early life can have substantial influences on adult health. This article reviews the current knowledge, recommendations, and approaches to feeding the normal newborn. The current understanding and approach to the common and sometimes difficult problem of gastroesophageal reflux (GER) in normal infants is also discussed.
Neonatal nutrition
There is accumulating evidence that nutrition and growth in early life can have substantial influences on adult health. This article reviews the current knowledge, recommendations, and approaches to feeding the normal newborn. The current understanding and approach to the common and sometimes difficult problem of gastroesophageal reflux (GER) in normal infants is also discussed.
Breastfeeding
Based on the many demonstrated benefits for babies and mothers, the World Health Organization (WHO), the American Academy of Pediatrics (AAP), and Institute of Medicine recommend the exclusive use of human milk for healthy term infants for the first 6 months of life, and continued breastfeeding for at least 12 months. The public health goal for Healthy People 2020 is for 82% of mothers to initiate breastfeeding, 60% of mothers to be breastfeeding at 6 months, and 34% to be breastfeeding at 1 year. The Centers for Disease Control and Prevention (CDC) tracks these breastfeeding rates and issues a breastfeeding report card yearly. Significant progress has been made toward achieving these breastfeeding goals, and in 2011 79% of women initiated breastfeeding. However, additional progress is necessary in the duration and exclusivity of breastfeeding. The most recent data on breastfeeding rates and the goals of Healthy People 2020 are shown in Fig. 1 .
To support higher breastfeeding rates, additional objectives of Healthy People 2020 include increasing the proportion of employers that have worksite lactation support programs, reducing the number of breastfed newborns who receive formula supplementation within the first 2 days of life, and increasing the proportion of live births that occur in facilities that provide recommended care for lactating mothers and their babies.
Although there has been progress in overall breastfeeding rates, these gains have not been uniform across all populations and geographic regions. Breastfeeding rates are lower for black infants, infants of mothers with lower incomes, and mothers with less education. Breastfeeding rates are lower in the southern United States and in rural areas. Health care workers should be aware of these disparities so that they can focus their attention on these groups to educate about and support breastfeeding, and help others overcome barriers to breastfeeding.
Breastfeeding and Clinical Outcomes
There is growing evidence that breastfeeding conveys important benefits during childhood and in later adult life, and to breastfeeding mothers. However, the evidence for these benefits comes almost entirely from observational cohort studies and not randomized clinical trials; randomized controlled trials of breastfeeding are widely considered to be impractical and unethical. Observational trials of clinical benefit have not always been consistent and can be subject to bias and contain multiple confounders. However, careful evaluation of multiple studies evaluating breastfeeding effects in clinical outcomes has been conducted, and meta-analyses performed. Based on these meta-analyses, there is convincing evidence of the beneficial effects of breastfeeding on a variety of infant and maternal clinical outcomes. A list of those significant outcomes is provided in Box 1 .
Infant
Otitis media
Recurrent otitis media
Respiratory tract infection
Asthma
Atopic dermatitis
Gastroenteritis
Type 1 and 2 diabetes
Leukemia
Sudden infant death syndrome
Mother
Breast cancer
Ovarian cancer
Several other benefits associated with breastfeeding have also been reported, but the evidence has been inconsistent and/or less convincing. This includes associations between breastfeeding and cognitive development, obesity in later life, cardiovascular mortality in adulthood, and postpartum depression.
Composition of Human Milk
Human milk is a complex and dynamic fluid that supports ideal infant growth and immune function development. The composition of human milk changes over time, and contains live cells along with macronutrients and micronutrients and bioactive factors.
Colostrum is the first fluid secreted by the breast following delivery, and has an intense yellow color because of the high concentration of carotenoids. Colostrum is produced in low quantities for the first few days, and contains bioactive components including secretory IgA, lactoferrin, leucocytes, and epidermal growth factor. Compared with later milk, colostrum contains relatively low concentrations of lactose, potassium, and calcium and higher levels of sodium chloride and magnesium. As lactose secretion becomes more efficient and milk lactose concentration increases, the colostrum/milk sodium concentration decreases proportionally.
Transitional milk appears at 5 to 14 days and contains increased amounts of lactose, fat, and total calories along with lower concentrations of immunoglobulins and total proteins. At 2 to 4 weeks, human milk is considered mature and the composition remains stable for the next several months. The change in macronutrient concentration in human milk over time is shown in Fig. 2 .
The macronutrient mineral, vitamin, and micronutrient concentration of mature human milk is shown in Table 1 . It must be pointed out that Table 1 lists average composition values; there is substantial variability in the nutrient content of human milk across individual mothers. Furthermore, aliquots of milk from one mother can also be quite different in composition. However, the mother-infant dyad seems to successfully adapt to these variations, and successful breastfeeding and normal infant growth is achieved for most mothers and infants.
| Energy | 66 ± 9 kcal |
| Protein | 1.3 ± 0.2 g |
| Fat | 3.0 ± 0.9 g |
| Lactose | 6.2 ± 0.6 g |
| Calcium | 28 ± 7 mg |
| Phosphorus | 15 ± 4 mg |
| Sodium | 18 ± 4 mg |
| Potassium | 53 ± 4 mg |
| Chloride | 42 ± 6 mg |
| Iron | 0.03 ± 0.01 mg |
| Vitamin D | 2.2 ± 0.4 IU/100 mL |
Human milk contains live cells and a large variety of bioactive substances. Macrophages, T cells, and lymphocytes are all found in human milk, with macrophages being the predominant cell type. These cells most likely perform an important host defense function for the infant. Multiple bioactive factors are present in human milk including immunoglobulins, growth factors, cytokines, and other small molecules. A partial list of bioactive substances contained in human milk along with their proposed function is shown in Table 2 .
| Compound | Proposed Function |
|---|---|
| Immunoglobulins (IgA, IgM, IgG) | Infection prevention |
| Cytokines | Infection prevention, reduce inflammation |
| Oligosaccharides | Promote beneficial flora |
| Nucleotides | Promote beneficial flora |
| Lactoferrin | Intestinal growth, immunomodulation |
| Epidermal growth factor | Intestinal maturation and repair |
| Insulin-like growth factor 1 and 2 | Tissue growth |
| Erythropoietin | Prevention of anemia, intestinal development |
| Vascular endothelial growth factor | Regulation of angiogenesis |
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