Development of the Human
Baby
Day 1 - The first
cell divides into two, the two into four, and so on.
5-9 days - The new
individual burrows into the wall of the womb.
14 days - The
mother's menstrual period is suppressed by a hormone produced by her
child.
18 days - The heart
is forming. Soon, eyes start to develop.
20 days - The
foundation of the brain, spinal cord and nervous system are laid.
24 days - The heart
begins to beat.
28 days - Muscles
are developing along the future spine. Arms and legs are
budding.
30 days - The child
has grown 10,000 times its original size to 6-7 mm (1/4 ") long.
The brain has human proportions. Blood flows in the baby's veins
but stays separate from the mother's blood.
35 days - The
pituitary gland in the brain is forming. The mouth, ears and
nose are taking shape.
42 days - The
skeleton is formed. The brain coordinates the movement of
muscles and organs. Reflex responses have begun. The penis
is forming in boys. The mother now misses her second period.
43 days - Brain
waves can now be recorded.
45 days -
Spontaneous movements have begun. Buds of milk teeth have
appeared.
7 weeks - Lips are
sensitive to touch. Ears may resemble family patterns.
8 weeks - The child
is well proportioned. Now a small scale babe, 3 cm (1 1/8")
long, and weighing a gram (1/30 oz.) Every organ is present.
The heart beats sturdily. The stomach produces digestive juices.
The liver makes blood cells. The kidneys begin to function.
Taste buds are forming.
8 1/2 weeks -
Fingerprints are being engraved. Eyelids and palms of hands are
sensitive to touch.
9 weeks - The child
will bend fingers around an object placed in the palm. Thumb
sucking occurs. Fingernails are now forming.
10 weeks - The body
is sensitive to touch. The child squints, swallows, puckers up
brow and frowns.
11 weeks - The baby
urinates, makes complex facial expressions, even smiles.
12 weeks - The
baby's vigorous activity shows distinct individuality. The child
can kick, turn feet, curl and fan toes, make a fist, move thumbs, bend
wrists, turn the head, open the mouth, and press lips tightly
together. Breathing is practiced.
13 weeks - The face
is prettier, facial expressions resemble the parents'. Movements
are graceful, reflexes vigorous. Vocal chords are formed, but
without air the baby cannot cry. Sex organs are apparent.
4 months - The
child can grasp with hands, swim and turn somersaults.
4-5 months - The
mother first feels the baby's movements.
5 months - Sleeping
habits appear, but a slammed door will provoke activity. The
child responds to sounds in frequencies too high or low for adults to
hear.
6 months - Fine
hair grows on eyebrows and head. Eyelash fringe appears.
Weight is about 640 g (22 oz), height 23 cm (9"). Babies born at
this age have survived.
7 months - Eye
teeth are present. Eyelids open and close, eyes look around.
Hands grip strongly. Mother's voice is heard and recognized.
8 months - Weight
increases by 1 kg (over 2 lbs), and baby's quarters get cramped.
9 months - The
child triggers labor and birth occurs, usually 255 - 275 days after
conception. Of 45 generations of cell divisions before
adulthood, 41 have taken place. Four more will come during the
rest of childhood and adolescence.
|