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Prenatal Development
and the Newborn Period
How Children Develop (3r
d
ed.)
Siegler, DeLoache & Eisenberg
Chapter 2
Overview

Prenatal
Development

The Birth
Experience

The Newborn
Infant
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Prenatal Development
Conception, Developmental
Processes, and
Early Development
Fetal Behavior, Experience,
and Learning
Hazards to Prenatal
Development
Conception


Results from the union of two gametes, the egg and the sperm
Gametes produced through specialized cell division, meiosis:

Each has only half the genetic material of all other normal cells in the
body
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Prenatal Development
1. Ovum (1/175 inch) + Sperm (1/500 inch) = Baby
1. Of 360 million released by male, only 100 reach
ovum.
 Sperm live for 48 hours – they swim for 6 hours, they lie in wait.
Sex Differences
Begin at Conception

Approximately 120 to 150 males are
conceived for every 100 females
How and why?


to the egg than X
chromosome sperm
Male embryos are miscarried at higher
rates, and boys are more vulnerable to
developmental disorders and illness
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Sex Differences
Begin at Conception
The Zygote

The fertilized egg, or zygote, has a full complement of
human genetic material, half from each parent

Marks the beginning of the three periods of prenatal
development

Germinal: Begins with conception and lasts until the
zygote becomes implanted in the uterine wall. Rapid
cell division takes place.
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The Zygote

Embryonic: Following implantation, major
development occurs in all the organs and systems of
the body.

Fetal: Continued development of physical structures
and rapid growth of the body. Increasing levels of
behavior, sensory experience, and learning.
Periods of
Prenatal Development
Germinal
(conception - 2 weeks)
Embryonic
(3 rd - 8th week)
Fetal
(9 th week - birth)
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The Cells

Four major developmental
processes transform a
zygote into an embryo and then into a fetus
1.
2.
3.
4.
Cell division results in the proliferation of cells
Cell migration is the movement of cells from their
point of origin to somewhere else in the embryo
Cell differentiation transforms the embryo’s
unspecialized stem cells into roughly 350
different types of cells
The selective death of certain cells, or
apoptosis, also enables prenatal development
The Role of Hormones

Hormones play a crucial role in sexual
differentiation


All human fetuses can develop either male or
female genitalia, depending on the presence or
absence of testosterone
One of the many ways in which the fetus acts
as an instigator of its own development
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The Blastocyst

By the 4th day after conception, the
zygote arranges itself into a hollow
sphere of cells with a bulge of cells,
the inner cell mass, on one side

The inner cell mass eventually forms
into the embryo
Protecting the Fetus

The placental membrane is a barrier against
some, but not all toxins and infectious agents

The amniotic sac, a membrane filled with
fluid in which the
fetus floats,
provides a
protective
buffer for
the fetus
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The Fetus: An active contributor
to its own development

By 12 weeks after gestation, most of
the movements that will be present at
birth have appeared

Swallowing amniotic fluid promotes the
development of the palate and aids in the
maturation of the

Pulling in and expelling small amounts of
amniotic fluid help the
become functional
Sensation

The sensory structures are present
relatively early in prenatal development
and play a vital role in fetal development
and learning

The fetus experiences tactile stimulation as
a result of its own activity, and tastes and
smells the amniotic fluid

It responds to sounds from at least the
6th month of gestation

Prenatal visual experience, however, is
negligible
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Fetal Learning

At 32 weeks’
gestation, the
fetus decreases
responses to
repeated or
continued
stimulation, a
simple form of
learning called
Fetal Learning

Newborn infants
have been shown to
recognize rhymes
and stories presented
before birth

Newborns also prefer
smells, tastes, and
sound patterns that
are familiar because
of prenatal exposure
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Miscarriage

By far the most common misfortune in
prenatal development is spontaneous
abortion (miscarriage)

Around 45% or more of conceptions
result in very early miscarriages, and
about 15-20% of pregnancies of which
women are aware are miscarried

The majority of embryos that miscarry
very early have
Teratogens (Greek: teras – monstrosity):


Environmental agents that
have the potential to cause
harm during prenatal
development
Timing is a crucial factor
in the severity of the
effects of potentially
harmful agents
 Many agents cause
damage only if
exposure occurs during
a sensitive period in
development
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p. 60
Sensitive Periods
Teratogens
What effects impact of a teratogen?






Amount and length of exposure.
Genetic make-up of mother and baby.
Multiple negative factors (poor nutrition,
no medicine).
Age of organism at time of exposure.
Teratogens include legal as well as
illegal substances...
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Some Environmental Hazards
to Fetus or Newborn
p. 62
Prescription and
non-prescription drugs
Any drug that mother takes affects fetus.
Good example is the anti-naseau thalidomide.

But, many pregnant women take unprescribed drugs:

Aspirin: linked to low birth weight (LBW), infant
death, poor motor development…and on and on.

Caffeine (heavy use): linked to LBW, miscarriage,
irritable and vomiting newborns.
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Teratogens

Maternal alcoholism can lead to fetal alcohol syndrome
(FAS), which is associated with mental retardation, facial
deformity, and other problems
FAS is the leading cause of mental retardation in western civilization.
Teratogens

Cigarette smoking during
pregnancy is linked to
retarded growth and low
birth weight

Cigarette smoking has also
been linked to SIDS (sudden
infant death syndrome),
although the ultimate causes
of SIDS are still unknown

Parents can reduce the risk by
, putting babies to
sleep on their backs, using firm mattresses and no pillows,
not wrapping infants in many blankets
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Teratogens
•
cocaine babies born yearly
Babies born to cocaine users

Physical: Eye, bone, genital, kidney, heart deformities.
Babies born to users of heroin & methadone:
 Physical: LBW, physical defects, breathing problems, drug
addicted
 Psychological: Less attentive, motor development slowed.
Marijuana – less is known and mixed findings.
 Evidence of disturbed sleep, startles, tremors.
Maternal Factors

The age, nutrition, disease, and stress-level of the mother
have an impact on prenatal development

Infants born to girls 15 years or younger are three to four times
more likely to die before their first birthday than are those
whose mothers are in their 20s

Inadequate nutrients or vitamins
such as folic acid can have
dramatic consequences
(e.g., growth of the fetal brain)
babies born
undernourished yearly in US. Only
72% of impoverished
mothers given extra food.
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Table 4.5
Nutritional Need Difference Between Non-pregnant and Pregnant Women (24 Years Old)
Nutrient
Folic acid
Vitamin D
Iron
Calcium
Phosphorus
Pyridoxine
Thiamin
Zinc
Riboflavin
Protein
Iodine
Vitamin C
Energy
Magnesium
Niacin
Vitamin B-12
Vitamin A
Nonpregnant
180 mcg
5 mg
15 mg
800 mg
1.6 mg
1.1 mg
12 mg
1.3 mg
50 g
150 mcg
60 mg
2200 kcal
280 mg
15 mg
2.0mcg
800mg
Pregnant
400 mcg
10mg
30 mg
1200 mg
1200 mg
2.2 mg
1.5 mg
15 mg
1.6 mg
60 g
175 mcg
70 mg
2500 kcal
320 mg
17 mg
2.2 mcg
800 mg
Percent Dietary Sources
Increase
+122
+100
+100
+50
+50
+38
+36
+25
+23
+20
+17
+17
+14
+14
+13
+10
0
Leafy vegetables, liver
Fortified dairy products
Meats, eggs, grains
Dairy products
Meats
Meats, liver, enriched grains
Enriched grains, pork
Meats, seafood, eggs
Meats, liver, enriched grains
Meats, fish, poultry, dairy
Iodized salt, seafood
Citrus fruits, tomatoes
Proteins, fats, carbohydrates
Seafood, legumes, grains
Meats, nuts, legumes
Animal proteins
Dark green, yellow, or orange
fruits and vegetables, liver
Source: Data from Reece et al., 1995. From Reece, E.A., Hobbins, J.C., Mahoney, M.J., and Petrie, R.H. (1995) HANDBOOK OF MED ICINE
OF T HE FET US AND THE MOT HER. Copyright © 1995. Used by permission of Lippincott Williams & Wilkins (http://lww.com)
The Birth Experience

Approximately 38 weeks after conception, contractions
of the uterine muscles begin, initiating the birth of the
baby

Research on the birth process has revealed that many
aspects of the birth
experience, including
squeezing in the birth
canal, have adaptive
value and increase the
likelihood of survival for
the newborn
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Psychological Stress
High anxiety linked to miscarriage, LBW, respiratory illness
Why?
• Under stress blood rushes to heart, brain, muscles - away
from uterus.
• Anxious women more likely to smoke, drink, eat poorly.
Reduced by partner, friends:
complicated pregnancy,
complication.
with help had
without help had
Maternal Age:
• Birth in 30s are increasing (best is 16-34).
• But, less problems if mother is healthy.
Assessing the Newborn’s Condition – Apgar Scale
Rating from 0-2 on five ratings
Score of 7+ is good, 4-6 help needed, 3- is bad.
The Newborn’s
Appearance
Average = 20 inches
long, 7½ pounds.
Big head – they learn
quickly but are
immobile.
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Interacting with the
Environment

State: The infant’s
level of arousal and
engagement in the
environment

Ranges from deep
sleep to intense activity

Is an important
influence in the
newborn’s exploration
of the world
Newborn States
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Sleep


Newborns sleep twice as much
as young adults
The pattern of two different
sleep states changes
dramatically


REM (rapid eye movement) sleep:
An active sleep state associated
with dreaming in adults
Non-REM sleep: A quiet or deep
sleep state characterized
Sleep

REM sleep constitutes fully 50% of a newborn’s total
sleep time and declines rapidly to only 20% by 3 or
4 years of age...

Why?
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Infant Mortality Worldwide (2002)
p. 75
Infant Mortality

Death during the first year after birth
(infant mortality) has become a relatively rare
event in the Western industrialized world

However, rates in the United States are the 23rd
highest in the world...

African-American infants are more than twice as
likely to die before their first birthday as EuroAmerican babies

Why?
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Low Birth Weight Infants
Infants weighing less than 5.5 pounds
(2,500 grams) are considered to be of
low birth weight (LBW)


LBW infants born at or before 35 weeks after
conception are described as premature

Other LBW infants are referred to as small for
gestation age (SGA) when their birth weight is
substantially less than the norm for their
gestational age
LBW Infants

As a group, LBW babies experience
more medical complications, have
more developmental difficulties, and
present special challenges for parents

However, the majority of LBW
babies turn out quite well

They need extensive parent
contact and more touch
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Risk Factors

Tend to occur
together in the world

A negative outcome
is more likely when
there are multiple
risk factors

Despite multiple risk
factors, however,
some individuals do
well
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