What is the BMR like in newborn infants?

What is the BMR like in newborn infants?

• A. It is highest in infancy
• B. It is lowest in infancy
• C. It is the same as adults
• D. It is lowest at birth and increases

Answer: (A)

Newborns have a very high metabolic rate because growth and development are occurring rapidly and many organs are highly active. Their bodies also need more energy per unit of body weight to support brain growth, organ maturation, and maintaining body temperature in the face of a large surface area-to-mass ratio. This combination means the basal metabolic rate is highest during infancy, especially when compared on a per-kilogram basis with older children and adults. As children grow, the rate per kilogram declines—even though total energy needs rise with bigger body size—so infancy stands out as the period with the greatest metabolic demand relative to body weight.

Newborns have a very high metabolic rate because growth and development are occurring rapidly and many organs are highly active. Their bodies also need more energy per unit of body weight to support brain growth, organ maturation, and maintaining body temperature in the face of a large surface area-to-mass ratio. This combination means the basal metabolic rate is highest during infancy, especially when compared on a per-kilogram basis with older children and adults. As children grow, the rate per kilogram declines—even though total energy needs rise with bigger body size—so infancy stands out as the period with the greatest metabolic demand relative to body weight.