| |
Capítulo 43 5 a 6 Meses (20 a 24 Semanas): Responde ao Som; Cabelo e Pele; Idade de Viabilidade
|
| |
| By 24 weeks
the eyelids reopen
and the fetus exhibits
a blink-startle response.
This reaction to sudden,
loud noises
typically develops earlier
in the female fetus.
|
| Several investigators report
exposure to loud noise
may adversely affect
fetal health.
Immediate consequences
include prolonged
increased heart rate,
excessive fetal swallowing,
and abrupt behavioral changes.
Possible long-term consequences
include hearing loss.
|
| The fetal respiratory rate
can rise as high
as 44 inhalation-exhalation
cycles per minute.
|
| During the third
trimester of pregnancy,
rapid brain growth consumes
more than 50% of the energy
used by the fetus.
Brain weight increases
between 400 and 500%.
|
| By 26 weeks
the eyes produce tears.
The pupils respond to light
as early as 27 weeks.
This response regulates
the amount of light
reaching the retina
throughout life.
|
| All components required
for a functioning sense
of smell are operational.
Studies of premature babies
reveal the ability
to detect odors
as early as 26 weeks
after fertilization.
Placing a sweet substance
in the amniotic fluid
increases the rate
of fetal swallowing.
In contrast, decreased
fetal swallowing
follows the introduction
of a bitter substance.
Altered facial expressions
often follow.
|
| Through a series
of step-like leg motions
similar to walking,
the fetus performs somersaults.
|
| The fetus appears
less wrinkled
as additional fat deposits form
beneath the skin.
Fat plays a vital role
in maintaining body temperature
and storing energy after birth.
|
Capítulo 44 7 a 8 Meses (28 a 32 Semanas): Discriminação de Sons, Estados Comportamentais
|
| |
| By 28 weeks the fetus
can distinguish
between high- and
low-pitched sounds.
|
| By 30 weeks, breathing movements
are more common
and occur 30 to 40% of the time
in an average fetus.
|
| During the last 4 months
of pregnancy,
the fetus displays periods
of coordinated activity
punctuated by periods of rest.
These behavioral states
reflect the ever-increasing
complexity
of the central nervous system.
|
Capítulo 45 Os Membros e a Pele
|
| |
| By approximately 32 weeks,
true alveoli,
or air "pocket" cells,
begin developing in the lungs.
They will continue to form
until 8 years after birth.
|
| At 35 weeks the fetus
has a firm hand grasp.
|
| Fetal exposure
to various substances
appears to affect flavor
preferences after birth.
For instance, fetuses
whose mothers consumed anise,
a substance which gives
licorice its taste,
showed a preference
for anise after birth.
Newborns without fetal
exposure disliked anise.
|
Capítulo 46 9 Meses até o Nascimento (36 Semanas até o Nascimento)
|
| |
| The fetus initiates labor
by releasing large amounts
of a hormone called estrogen
and thus begins the transition
from fetus to newborn.
Labor is marked by powerful
contractions of the uterus,
resulting in childbirth.
|
| From fertilization
to birth and beyond,
human development is dynamic,
continuous, and complex.
New discoveries about
this fascinating process
increasingly show the vital
impact of fetal development
on lifelong health.
As our understanding of early
human development advances,
so too will our ability
to enhance health -
both before and after birth.
|
