Early Childhood and Physical Development

Infancy Weight

• The average newborn weighs approximately 7.5 pounds (5.8lb – 8.13lb) at full-term
• In the first few days, newborns typically lose weight as they adjust to life outside of the womb and get used to feeding; however, this is followed by a rapid period of growth.
• By the time an infant is ~4 months old, they usually double in weight
• By one year their weight has tripled and by age 2, the weight is 4x their original birth weight.
• The average 2-year-old weighs 26 to 32 pounds
  • Growth rate is considerably slower in the second year.

Body Proportions

• Body proportions of infancy are also not evenly distributed
• The head is significantly larger – taking up 50 percent of body weight when developing in utero, and 25 percent of body weight in infancy
• Younger babies need support for head, tummy time to increase head control and support
• Head should be protected, and baby should never be shaken.
  • Shaken baby syndrome: brain swelling and hemorrhaging.
• As individuals develop from infancy through adulthood, one of the most noticeable physical changes is that the head becomes smaller in relation to the rest of the body.
  • At 2 months, the head is about half the total body length; at 5 months, about a third the size.
  • A newborn’s head is about one-quarter the total body length; and the proportion continues to change into adulthood.

Early Reflexes

• Reflex behaviors are automatic, innate responses to stimulation.
  • They are controlled by the lower brain and they govern involuntary process, such as breathing and heart rate.
• Babies are born with innate reflexes to prime them to survive and thrive
• Related to instinctive needs for survival and protection
• Reflexes: built-in reactions to stimuli that govern the baby’s movements, which are automatic and beyond their control.
  • Rooting
  • Sucking
  • Moro
  • Grasping

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