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Nutrition in Infants


Deborah M. Consolini

, MD, Sidney Kimmel Medical College of Thomas Jefferson University

Last full review/revision Sep 2019| Content last modified Sep 2019
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If the delivery was uncomplicated and the neonate is alert and healthy, the neonate can be brought to the mother for feeding immediately. Successful breastfeeding is enhanced by putting the neonate to the breast as soon as possible after delivery. Spitting mucus after feeding is common (because gastroesophageal smooth muscle is lax) but should subside within 48 hours. If spitting mucus or emesis persists past 48 hours or if vomit is bilious, complete evaluation of the upper gastrointestinal (GI) and respiratory tracts is needed to detect congenital GI anomalies.

Daily fluid and calorie requirements vary with age and are proportionately greater in neonates and infants than in older children and adults (see Table: Calorie Requirements at Different Ages*). Relative requirements for protein and energy (g or kcal/kg body weight) decline progressively from the end of infancy through adolescence (see Table: Recommended Dietary Reference Intakes* for Some Macronutrients, Food and Nutrition Board, Institute of Medicine of the National Academies), but absolute requirements increase. For example, protein requirements decrease from 1.2 g/kg/day at 1 year to 0.9 g/kg/day at 18 years, and mean relative energy requirements decrease from 100 kcal/kg at 1 year to 40 kcal/kg in late adolescence.

Nutritional recommendations are generally not evidence-based. Requirements for vitamins depend on the source of nutrition (eg, breast milk vs standard infant formula), maternal dietary factors, and daily intake.


Calorie Requirements at Different Ages*





< 6 months



1 year



15 years



* When protein and calories are provided by breast milk that is completely digested and absorbed, the requirements between 3 months and 9 months of age may be lower.

Feeding problems

Minor variations in day-to-day food intake are common and, although often of concern to parents, usually require only reassurance and guidance unless there are signs of disease or changes in growth parameters, particularly weight (changes in the child’s percentile rank on standard growth charts are more significant than absolute changes).

Loss of > 5 to 7% of birth weight in the first week indicates undernutrition. Birth weight should be regained by 2 weeks, and a subsequent gain of about 20 to 30 g/day (1 ounce/day) is expected for the first few months. Infants should double their birth weight by about 5 months.

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