The Developing Person
Through Childhood and Adolescence
Ninth Edition
Kathleen Stassen Berger
Part I
Chapter Four
Prenatal Development and Birth
CHAPTER PREVIEW
• Anticipating the birth of a child is one of life’s
most enriching experiences.
• The period of prenatal development is a time
of incredibly rapid growth.
• The emerging person develops from a single
cell into a fully functioning individual. This
development is outlined in Chapter 4,
followed by a discussion of the birth process.
CHAPTER PREVIEW (CONT.)
• The fetus becomes a separate human being who
begins life almost completely dependent upon its
caregivers.
• Problems that can occur—among them prenatal
exposure to disease, drugs, and other hazards—and
the factors that moderate the risks of teratogenic
exposure. One sign. problem is low birthweight,
which is generally linked to maternal malnutrition and
drug use.
• Concludes with a discussion of the significance of the
parent–newborn bond.
Figure 4.1 The Most Dangerous Jou
Table 4.1 Timing and Terminology
Prenatal Growth
• Germinal: The First 14 days
• Embryo: From the Third Through the
Eighth Week
• Fetus: From the Ninth Week Until
Birth
Germinal Period (First 14 days)
• The germinal period is the first two weeks of prenatal
development after conception, characterized by rapid
cell division and the beginning of cell differentiation.
• About a week after conception, the multiplying cells
(now numbering more than 100) separate into two
distinct masses. The outer cells form a shell that will
become the placenta (the organ that surrounds and
protects the developing creature), and the inner cells
form a nucleus that will become the embryo.
Germinal Period (Cont.)
• The first task of the outer cells is to
achieve implantation— that is, to embed
themselves in the nurturing lining of the
uterus.
• This is far from automatic; about 50
percent of natural conceptions and 70
percent of in vitro conceptions do not
implant. Thus, most new life ends
before an embryo begins.
Embryonic (3rd - 8th Weeks)
• Formless Mass becomes a distinct being
known as the embryo.
• A thin line down the middle of the embryo (the
primitive streak) forms a structure that becomes the
neural tube, then the brain and spinal column (the
central nervous system).
• In the fourth week, the cardiovascular system is
functioning; the eyes, ears, nose, and mouth start to
form. At five weeks, the arm and leg buds appear.
•
Embryonic (3rd to 8th Weeks)
• By the end of the second month,
the developing organism weighs
about 1 gram (1/30 ounce), is 21/2
centimeters (1 inch) long, and has
all the basic organs and body parts
of a human being (except the sex
organs).
From the Third Through the Eighth Week
What happens during the embryonic period of prenatal development?
Brain
As nerves and muscles form links to the brain,
the embryo now moves spontaneously, as the
brain begins to move muscles.
Facial
Features
Eyes and eyelids are developed. Eyes will continue
to migrate to the front of the head, where they
will eventually rest. Eyelids begin to grow
together and are only half closed. External,
middle, and inner ears are now fully formed.
External ears will continue to migrate to the side
of the head, where they will eventually rest.
External
sex organs
Urogenital membranes have developed into either
male or female organs, and ovaries or testicles
are visible. Clitoris or penis begins to form, but
distinguishing the embryo’s sex is difficult.
Overall
appearance
The head is still disproportionately large but is
erect and appears rounded. The neck is well
defined. The tail will disappear by the end of this
week. Cartilage begins to turn into bone. The
ectoderm layer is replaced by the beginnings of
skin. The body becomes evenly rounded, due to
the growth in the abdomen.
Intestines
The intestines begin to move from
the umbilical cord to the embryo’s
body cavity.
Arms, hands
and fingers
Arms are well formed, longer, and can
bend at elbows and move forward.
Fingers elongate and digits are fully
separated. Each finger has three digits,
and the thumb has two digits.
Brain
Facial
Features
Intestines
External sex
organs
Arms, hands
and fingers
Overall
appearance
11
Embryonic
• What body parts develop during
the embryonic period? The brain
and spinal column, eyes, ears,
nose, and mouth start to form as
do the heart, arms and legs. This
is followed by the upper arm,
forearm, palms, webbed fingers,
legs, knees, feet and webbed toes.
Prenatal Development
• Prenatal development is cephalocaudal,
meaning that it proceeds from “head to
tail,” and proximodistal, or from “near to
far."
Fetal Period (9th Week until Birth)
• In the fourth, fifth, and sixth months, the
heartbeat becomes stronger. Digestive and
excretory systems develop. Fingernails,
toenails, and buds for teeth form, and hair
grows (including eyelashes). The brain
increases about six times in size and
develops many new neurons (neurogenesis)
and synapses (synaptogenesis). Up to half a
million brain cells per minute are created at
peak growth during mid-pregnancy (Dowling,
2004).
Fetal Period
• During the fetal period, if the fetus is male
(XY), the SRY gene on the Y chromosome
signals the development of male sex organs.
If the fetus is female (XX), no signal is sent,
and the fetus begins to develop female sex
organs. Most functions of the brain are
gender-neutral; some neurological sex
differences occur in the third month.
Fetal Period
• At the end of the third month, the fetus has all
its body parts, weighs approximately 3
ounces (87 grams), and is about 3 inches
(7.5 centimeters) long.
• In the middle 3 months, the systems develop
more fully. The crucial factor in the fetus’s
attaining the age of viability, beginning at
about 22 weeks, is brain maturation, which is
essential to the regulation of basic body
functions, such as breathing and sucking.
Last Three Months
• In the last three months of prenatal life, the
lungs begin to expand and contract,
exercising muscles involved in breathing by
using the amniotic fluid as a substitute for air.
The valves of the heart go through a final
maturation, as do the arteries and veins
throughout the body. Among other things, this
helps to prevent “brain bleeds,” one of the
hazards of preterm birth in which paper thin
blood vessels in the skull collapse.
Table 4.2 Vulnerability During Prenat
Benefits of Prenatal Care
What are some prenatal tests?
19
Figure 4.3 Prenatal Growth of the Br
From the Ninth Week until Birth
What happens during the fetal period of prenatal development?
9 weeks through 38
weeks
9
1
2
1
2
2
2
3
3
6
0
4
8
2
6
fetus: A developing human organism from
the start of the ninth week after
conception until birth.
3
8
21
Birth
• Birth usually begins at about 38 weeks after
conception, when the fetus’s brain signals the
release of hormones, specifically oxytocin,
that trigger uterine contractions in the mother.
The baby is born, on average, after 12 hours
of active labor for first births and 7 hours for
subsequent births.
Figure 4.4 A Normal, Uncomplicated
Birth
• The quality of the birth experience depends
on many factors, including the parents’
preparation for birth, the skill of the birth
attendants, the position and size of the fetus,
and the customs of the culture.
• Cesarean sections (c-sections) account for
more than one-third of U.S. births. Less
studied is the epidural, a spinal injection to
ease pain. Another medical intervention is
induced labor.
Birth
• Most U.S. births occur in hospital labor
rooms. Another 5 percent occur in birthing
centers. Only 1 percent of U.S. births take
place at home. They are usually normal and
healthy but risk complications.
• Many North American mothers today use a
professional birth coach, or doula, to assist
them.
Apgar Scale
• Used to assign a score between 0 and 2 to
the newborn’s heart rate, breathing, muscle
tone, color, and reflexes at one minute after
birth and again at five minutes. A score of 7
or better indicates the newborn is not in
danger; below 7, that the infant needs help in
establishing normal breathing; and below 4,
that the baby is in critical condition and needs
immediate medical attention.
Table 4.3 Criteria and Scoring of the
Preterm and a Robust Newborn
• What are three major reasons why
pregnancy continues months after the
fetus could live outside the uterus? The
critical difference between life and death,
or between a fragile preterm baby and a
robust newborn, is maturation of the
neurological, respiratory, and
cardiovascular systems.
Teratogens
Include such substances or conditions as
viruses, drugs, chemicals, stressors, and
pollutants that can impair prenatal
development and lead to birth defects, even
death. Teratogens that tend to harm the
prenatal brain are called behavioral
teratogens. Approximately 20 percent of all
children have behavioral difficulties that could
be related to behavioral teratogens.
Teratology
• Teratology is a science of risk
analysis, which attempts to
evaluate what factors can make
prenatal harm more, or less, likely
to occur.
Teratogen
• Three crucial factors that determine
whether a specific teratogen will
cause harm, and of what nature, are
the timing of exposure, the amount of
exposure, and the developing
organism’s genetic vulnerability to
damage from the substance.
Teratogen
• Although each body structure has its own
critical period during which it is most
susceptible to teratogenic damage, health
during the entire fetal period affects the brain.
• Some teratogens have a cumulative effect on
the developing individual. For other
teratogens, there is a threshold effect; that
is, the substance is virtually harmless until
exposure reaches a certain level.
Table 4.4 Teratogens: Effects of Expo
Table 4.4 Teratogens: Effects of Expo
Fetal Alcohol Syndrome
• Early in pregnancy, large doses of
alcohol can trigger the physical,
behavioral, and mental symptoms of
fetal alcohol syndrome (FAS). Later
in pregnancy, alcohol is a behavioral
teratogen, the cause of fetal alcohol
effects (FAE).
Problems
• A deficiency in folic acid in the mother’s diet
may result in neural-tube defects, such as
spina bifida or anencephaly. These also
occur more commonly in certain ethnic
groups.
• Early prenatal care protects fetal growth,
makes birth easier, and makes parents better
able to cope with birth. Laboratory test results
sometimes produce false positives because
they incorrectly suggest a problem that does
not exist.
Low Birthweight
• Low birthweight (LBW) is defined as birthweight that
is less than 51/2 pounds (2,500 grams). Babies who
weigh less than 3 pounds, 5 ounces (1,500 grams)
are classified as very low birthweight (VLBW); those
who weigh less than 2 pounds, 3 ounces (1,000
grams) are classified as extremely low birthweight
(ELBW).
• Low-birthweight infants who are born 3 or more
weeks early are called preterm. Others, born close to
the due date but weighing less than most full-term
newborns, are called small for gestational age (SGA).
Culture Influence
• Not only are fathers important to the birth
process, but the entire social network and
culture are crucial influences. This is most
apparent in what has been called the
Hispanic paradox, which says that although
immigrants to the U.S. are poorer and have
less adequate prenatal care, they have
healthier newborns than American-born
mothers of the same ethnic background.
LBW
• Worldwide, the LBW rate is lower than it
was 20 years ago. The U.S. infant
mortality rate of about 7 per 1,000 is
primarily because of low birth weight.
• In US, African Americans have LBW
newborns twice as often as the national
avg. The birth rate has < in the past 20
yrs. Nations with many small newborns
are also nations where hunger is high.
Figure 4.2 Each Critical Day
Birth Complications
• More likely if the fetus is already at
risk because of low weight, preterm
birth, genetic abnormality, or
teratogenic exposure or because the
mother is unusually young, old, small,
or ill.
Cerebral Palsy (CP)
• Researchers
now
realize
that
cerebral palsy (difficulties with
movement control resulting from
brain damage) results from genetic
vulnerability, worsened by teratogens,
maternal infection, and a birth in
which anoxia (a temporary lack of
oxygen) occurs.
NEWBORN
• Newborns are social beings that
respond to others in many ways. The
test that measures behavioral
responsiveness in newborns is the
Brazelton Neonatal Assessment
Scale (NBAS). The test measures 46
behaviors, 20 of which are reflexes.
REFLEXES
• The breathing reflex is an involuntary
response that causes the newborn to
take the first breath even before the
umbilical cord is cut. Other reflexive
behaviors that maintain oxygen are
hiccups, sneezes, and thrashing.
REFLEXES
• Shivering, crying, and tucking the
legs close to the body are examples
of reflexes that help to maintain
constant body temperature.
REFLEXES
• A third set of reflexes relates to
feeding - suck anything that touches
the lips; to turn their heads and start
to suck when something brushes
against their cheek-rooting reflex.
Other important reflexes that facilitate
this behavior are swallowing, crying,
and spitting up.
FATHER
• The presence of the father reduces
complications during birth - helps the
mother.
• Many fathers experience symptoms of
preg.- weight gain, indigestion, and pain
during labor. Crucial re the birth
experience is the formation of a strong
parental alliance between the parents.
Postpartum Depression
• Some mothers may develop feelings of sadness and
inadequacy, or postpartum depression, in the days
and weeks after birth.
• What are the signs of postpartum depression? One
sign is feelings of euphoria after birth that give way to
sleeplessness and feelings of sadness and
inadequacy. Caring for the infant becomes a burden
or seems overwhelming.
Parent-Infant Bond
• The term parent–infant bond is used to emphasize
the strong, loving connection that forms between
parent and child in the early moments after birth.
• For vulnerable infants, parents are encouraged to
help with early caregiving in the hospital. This
reduces stress in both infant and parents. One ex. of
early caregiving is kangaroo care - mothers of lowbirthweight infants spend extra time holding their
infants between their breasts.
Kangaroo Care
• What are the results of kangaroo care? A
rise in infant adjustment to life outside of
the womb as well as increased parental
sensitivity and effectiveness are results of
kangaroo care. Results are seen in weight
gain, more time in deep stages of sleep
and more alert awake time spent by
infants receiving kangaroo care.