Page 159 - 86 human physiology part-2

Chapter 19

Some newborns have a fine, downy body hair called lanugo. It may be particularly noticeable on
the back, shoulders, forehead, ears and face of premature infants. Lanugo disappears within a few
weeks. Likewise, not all infants are born with lush heads of hair. Some may be nearly bald while others
may have very fine, almost invisible hair. Some babies are even born with a full head of hair. Amongst
fair-skinned parents, this fine hair may be blond, even if the parents are not. The scalp may also be
temporarily bruised or swollen, especially in hairless newborns, and the area around the eyes may be
puffy.

A newborn's genitals are enlarged and reddened, with male infants having an unusually large
scrotum. The breasts may also be enlarged, even in male infants. This is caused by naturally-occurring
maternal hormones and is a temporary condition. Females (and even males) may actually discharge
milk from their nipples, and/or a bloody or milky-like substance from the vagina. In either case, this is
considered normal and will disappear in time.

The umbilical cord of a newborn is bluish-white in color. After birth, the umbilical cord is
normally cut, leaving a 1–2 inch stub. The umbilical stub will dry out, shrivel, darken, and
spontaneously fall off within about 3 weeks. Occasionally, hospitals may apply triple dye to the
umbilical stub to prevent infection, which may temporarily color the stub and surrounding skin purple.

Newborns lose many of the above physical characteristics quickly. Thus prototypical older babies
look very different. While older babies are considered "cute", newborns can be "unattractive" by the
same criteria and first time parents may need to be educated in this regard.

Neonatal jaundice
Neonatal jaundice is usually harmless: this condition is often seen in infants around the second
day after birth, lasting till day 8 in normal births, or to around day 14 in premature births. Serum
Bilirubin normally drops to a low level without any intervention required: the jaundice is
presumably a consequence of metabolic and physiological adjustments after birth. A common
treatment is to use bilirubin lights on the newborn baby.

Changes in body Size and Muscle fat makeup

By the end of the first year an infant's height is increased by 50% since its birth and by the age of 2
the baby will have grown 75% greater.

By 5 months a baby will have doubled it's weight, and tripled it's weight by the first year. By the
age of 2, a baby's weight will have quadrupled.

Infants and toddlers grow in little spurts over the first 21 months of life. A baby can go through
periods of 7 to 63 days with no growth but they can add as much as an inch in one 24 hour period.
During the day before a growth spurt, parents described their babies as irritable and very hungry.

The best way to estimate a child's physical maturity is to use skeletal age, a measure of bone
development. This is done by having a x-ray of the long bones of the body to see the extent to which
soft, pliable cartilage has hardened into bone.

374 | Human Physiology