Transcript Theories of Infant Development

Before Birth:
Prenatal Behavior
and Development
Fogel
Chapter 3
Created by Ilse DeKoeyer-Laros, Ph.D.
Overview Chapter 3
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Conception and Fertility
Applications: Family Planning
Developmental Processes
Individual Differences in Prenatal
Development
• Family and Society
Experiential Exercises
Conception & Fertility
• Conception: the union of an ovum and a
spermatozoon, creating a zygote (fertilized ovum)
• Spermatozoa & ova are known as gametes
• Twinning happens in about 1 in 80 pregnancies
– Dizygotic (DZ) or fraternal twins: two
ova are fertilized and two different
zygotes develop
– Monozygotic (MZ) or identical twins:
the fertilized zygote divides and splits
into two separate zygotes
Picture from: www.creative-baby-shower-ideas.com
Conception & Fertility
Fertility: the ability to contribute successfully to
fertilization or conception
– male fertility begins at puberty and, for most males,
lasts their entire life
– female fertility lasts until menopause; ova develop
prenatally but do not mature until puberty
Contraception & Family Planning
• How many people can the earth support?
– appr. 6 billion people on January 1, 2000 and by
2030, this is expected to have doubled
• Family planning & contraceptives
– especially important where the size of the population
outstrips the ‘s ability to provide for everyone
– depends on personal & cultural values and culturally
adapted interventions work the best
– education is a necessary ingredient in a successful
family planning program
Teenage Pregnancies
Teenage births increased until 1990s, then
declined. Risks involved with teen births include
– birth defects, infant death, low
birthweight
– teens show lower responsiveness
to babies & less mutual motherinfant affection and enjoyment
(compared to older mothers)
Picture from: blog.nj.com/parentalguidance/health
Teenage Pregnancies
Social systems perspective
– teenage mothers are 7 times as likely to be poor
before pregnancy as older mothers
– teen mothers & fathers are more likely to have low
academic performance & be unpopular among peers
– teen marriages often end in divorce
– children of teen parents are more prone to adolescent
delinquency, violence, and arrest than other teens
Education & Contraception
for Youth
Prevention should begin early & involve the entire
community and culture
– focus on internal locus of control,
academic achievement, effective life
choices, and poverty alleviation
– better pregnancy outcomes with
reduction of stress, social support,
prenatal care, and parental
involvement with the infant
Picture from: http://gainesvillecare.org/about/nine-months.php
Education & Contraception
for Youth
• 1990-2005: 50% of highschoolers engaged in
sexual activity
– the majority of teenagers do not have basic
knowledge of sexuality, conception & contraception
– more sex education is needed
• Education about responsible sexuality is more
effective than abstinence-only programs in
preventing sexual activity & pregnancy
Infertility
About 1 in 6 couples suffers from infertility – they
are unable to conceive successfully for at least
one year
– female infertility is usually caused by a failure to
ovulate (often treatable) or the unsuccessful journey
of the ovum to the Fallopian tubes (treated by surgery
and/or drugs)
– male infertility is caused by potentially treatable
factors (e.g., smoking ,tight underwear, hot baths or
saunas); or by injuries, underdeveloped testes, and
some childhood diseases
Enhancing Fertility
• Natural methods
– timing sexual intercourse around the time of ovulation
– good health, weight, diet, exercise; avoiding hot tubs
and saunas (males)
• Medical interventions
– artificial insemination
– in vitro fertilization (IVF)
• Some of these interventions raise ethical
dilemmas and health issues
Prenatal Developmental Processes
All cells in the body – except the gametes – have
the same set of genes and chromosomes:
– the genotype consists of a spiral-shaped molecule
called deoxyribonucleic acid (DNA)
– DNA is segmented into sections, each of which
contains a different set of bases
– each segment is called a gene
– genes are arranged in long strings
into chromosomes
Picture from: http://www.coolest-gadgets.com/search/model+of+DNA+strand
Prenatal Developmental Processes
Each of the body’s cells contains the same set of
genes and chromosomes
– 23 chromosomes in each gamete
– 46 chromosomes (23 pairs) in other cells represent
represent about 1 million bits of genetic information
Prenatal Developmental Processes
The number of genetically different individuals is
enormous
– each gamete contains a slightly different set of
chromosomes
– the particular pair that unite for fertilization is random
This rare set of twins, for
example, were born to
two parents of mixed race
(in the UK)
Picture from: www.parentdish.com
Prenatal Developmental Processes
• Two cell division processes
– mitosis: each chromosome copies itself before cell
division
– meiosis: cell division in the gametes, without copying
chromosomes
• Development of the zygote
– the number of cells grows rapidly through mitosis,
doubling every few hours
– because mitosis is an exact copying process, each of
these cells has the same genetic material
Prenatal Developmental Processes
How can different tissues and structures develop,
given identical genes in each cell?
– some cells are on the surface and some on the interior:
they are in contact with different environments
– different environments expose the cell to different
molecules moving into the cell
– these compose the epigenome – biochemical markers
that turn on or turn off the actions of particular genes
within each cell
Prenatal Developmental Processes
• Phenotype
– the result of a constant & dynamic interaction
between the genotype, the epigenome, and the
environment inside and outside of the cell
• Embryonic stem cells
– early in the process of the formation of different
regions, cells can be removed from one region and
placed in an entirely different one – they take on the
properties of the other cells around them
Prenatal Developmental Processes
Even though every cell in the embryo has the
same genes, because the epigenome is
responsive to the local environment,
different genes become active in different
types of cells
Prenatal
Developmental
Processes
The most common embryonic
structure is a tube
– in all animals, the first tube is
the gut
– in vertebrate animals, one of
the early-forming tubular
structures is the spinal cord
and spine
Types of Prenatal
Developmental Changes
• Changes in kind
– the zygote gradually differentiates into multiple kinds of tissue
– certain structures emerge and then disappear
• Changes in number
– cell numbers increase and decrease; but increase overall
• Changes in position
– e.g., the heart forms near the face
• Changes in size
– growth varies with the time and location of the organ
• Changes in shape
– the organism changes from an oval shape into an elongated
shape; there are also changes in the shape of cells and organs
Phases of Prenatal Development
Human gestation lasts about 38 weeks and
develops in three periods:
1. The period of the zygote: fertilization until implantation
into the uterine wall (about 2 weeks)
2. The period of the embryo: implantation until the end of
the 2nd month
3. The period of the fetus: the organism begins to
resemble a human and the bones begin to harden (2nd
– 9th month)
Phases of Prenatal Development
Examples of prenatal development:
• 3D slide shows at
–
news.bbc.co.uk/2/hi/in_pictures/384
7319.stm
–
slideshow.ivillage.com/parenting/pre
gnancy/calendar/your_babys_devel
opment
• 4D clips at
–
www.youtube.com
Picture from ivillage.com
The Period of the Zygote
At the end of the 2nd week, the zygote has
developed into a blastocyst
– consists of the embryonic disk,
surrounded by the amniotic sac and
the yolk sac
– triggers the secretion of human
chorionic gonadotropin (HCG)
hormones that inhibit menstruation
& are used in laboratory pregnancy
tests
The Period of the
Embryo
The embryonic disk
differentiates into three layers:
– endoderm: will become the digestive, urinary, and
respiratory systems
– mesoderm will become the muscles, bone, circulatory
system, and reproductive system
– ectoderm will become the central nervous system and
brain, the sense organs, and the skin, hair, nails, and
teeth
The Period of the Embryo
• Yolk sac: produces blood cells; becomes part of liver, spleen, and
bone marrow
• Amniotic sac: grows to cover the embryo and contains the amniotic
fluid (“cushion” for the fetus)
• The chorion is a membrane that surrounds all of these
developments – out of its outer surface, the placenta forms as a link
between the bloodstreams of mother and embryo
The Period of the
Embryo
There are rudimentary behaviors,
such as heartbeats, respiration,
and whole-body jerky movements
– the heart is beating by the end of the 1st month
– by 6 weeks, the limbs begin to differentiate; fingers &
toes will appear shortly
– has all of the major organs except genital organs
– by 4½ weeks, the embryo has a rudimentary sensory
system, but sense organs are not yet connected to
nerve fibers
– by 7 weeks, the embryo is responsive to touch in the
mouth region and will turn its head to the side
The Period of the Fetus
7-16 weeks
In this period, spontaneous movements emerge
– with maternal muscle
contractions, sounds, and
changes in maternal glucose
& oxygen levels
– become more localized and
specific over time
– reflexes emerge first
The Period of the Fetus
7-16 weeks
The purpose of these movements is not entirely
clear. However,
– preventing chicks & mice to move prenatally results in
deformations and movement problems
– fetal movement helps the development of nerve
endings in the sensory receptors
– possibly, early movements contribute to later hand
preferences
– early movements may help the fetus adapt to its
environment
The Period of the Fetus
7-16 weeks
Physical changes
– by 16 weeks, the fetus is about 3 inches & 1/2 ounce
– the brain forms two hemispheres around 9 weeks
– by 15 weeks, it communicates with the sense organs
& muscles and begins to inhibit movement
– external genitals form
• testosterone in male fetuses activates genes that induce the
development of external male genitals around 3 months; it
may also affect prenatal brain development
• female genitals do not require any specific hormone to
develop
The Period of the Fetus
17-22 weeks
Rapid brain development takes place
– subcortical & cortical
cells and pathways
inhibit uncontrolled,
spasmlike movements
– after 22 weeks,
movements are more
specialized & controlled
The Period of the Fetus
17-22 weeks
• New physical characteristics
– hair on the body (lanugo) & head, eyebrows &
eyelashes
– skin: vernix caseosa protects the delicate skin
– nails & tooth buds
• At 6 months, the fetus weighs about 2 pounds; it
is unlikely to survive if born prematurely
– esp. if less than 600 grams or less than 24 weeks
The Period of the Fetus
23-36 weeks
• Growth: 900 grams at 24 weeks to appr. 3,500
grams (7 pounds) at 36 weeks
• Active & quiet states become waking & sleeping
states
– sleep is divided into a period of quiet sleep and a
period of active or REM sleep
– the 32-week-old fetus spends about ¾ of its time in
REM sleep
The Period of the Fetus
23-36 weeks
• Can feel pain between 26-30 weeks (linked to
brain development)
• New movement patterns
– cry, grunt, yawn
– by the 8th month, thumb sucking and opens eyes
– grasping, postural adjustment movements
– fetus can see, hear, feel, and smell
• Could survive if born by about the 7th month,
with intensive care
The Period of the Fetus
23-36 weeks
• Fetuses also develop the capacity to learn
– distinguish voices (male & female; mother & stranger)
– newborns prefer songs or stories they heard
prenatally, as well as familiar smells and tastes
• Prenatal learning may
– serve as an early attachment mechanism
– orient the baby to the postnatal environment
– play a role in the development of connections
between sensory, motor, and information processing
areas of the brain
The Period of the Fetus
23-36 weeks
Do late-term fetuses have
psychological experiences?
Evidence suggests…
– the ability to self-regulate by 33 weeks
– beginnings of bodily self-awareness
Does prenatal enrichment have a
lasting effect?
– there is no good evidence for this yet
– still, singing, talking, and massaging can
be healthy & rewarding for mother & fetus
The Period of the Fetus
23-36 weeks
See a late-term fetus moving
around in the mother’s belly to
the father’s voice at
– www.youtube.com/watch?v=973dNQ-licM
Picture from http://www.jointeffortchiro.com
Individual Differences
Genetic Influences
• Depend on gene-environment interaction
• Genetic disorders can occur through
• polygenic inheritance
• dominant-recessive inheritance (e.g., PKU)
• sex-linked inheritance (e.g., Fragile X syndrome)
• Chromosomal disorders involve additions and
deletions of chromosomes
– e.g., Down’s syndrome
Individual Differences
Teratogens
• Environmental agents responsible for birth
defects are known as teratogens
– e.g., alcohol, drugs, and diseases
• Effects depend on
– when the exposure occurs: the earlier, the riskier
• ⅔ of all birth defects occur in the first trimester
– the size of the dosage & the length of exposure
• longer, larger doses create the greatest risk
Individual Differences
Teratogens
Fetal alcohol syndrome (FAS)
– mental retardation, facial abnormalities, hyperactivity,
growth retardation, more premature births &
miscarriages, lower birthweight, and heart defects
– 1 to 3 per 1,000 births in the United States
– the heaviest drinkers have a 30% higher risk of
having an FAS child, but children of moderate
drinkers may still develop fetal alcohol effects (FAE)
Individual Differences
Teratogens
Smoking
– respiratory problems, birth complications, growth
retardation, antisocial behavior, learning disabilities
– excitability, colic and gastrointestinal symptoms in
infancy & obesity, asthma and other respiratory
disorders, and conduct problems in childhood
– lowers boys’ sperm count and testes size when they
reach adolescence
– predisposes teens of both sexes to nicotine addiction
– passive smoking has effects just as severe as those
of direct smoking
Individual Differences
Teratogens
Cocaine
– reduces birthweight & creates circulatory, respiratory,
and urinary problems
– increases the risk of Sudden Infant Death Syndrome,
attentional difficulties, withdrawal, language delay,
and lags in motor development
– these problems may be due to other health risks (e.g.,
poor diet, poor prenatal care), poverty, maternal
depression, family disruption, child abuse, and
neglect – rather than the drug itself
• alleviation of these contextual factors can in most cases
eliminate the effects of the prenatal cocaine exposure
Individual Differences
Teratogens
Maternal Depression
– estimated 9-14% of women show depression during
pregnancy
– up to 35% of women take psychotropic medication
during pregnancy, primarily SSRIs
– in general, neither depression nor SSRIs cause birth
defects
– there is some evidence that newborns act somewhat
depressed (lower activity level, more sleeping, longer
latency to respond to stimulation) but these effects
generally decline over the next month after birth
Individual Differences
Teratogens
Maternal anxiety and stress
– fetuses: higher activity level
– infants: cried & fussed more and had difficulties with
emotion regulation & social behavior
– children: more likely to show symptoms of ADHD and
anxiety, lower attention ability, & socioemotional
problems
– adolescents: continue to show problems with ADHD
and anxiety & have lower IQ scores compared to
children of non-anxious mothers
– adults: more susceptible to mental illness, including
schizophrenia, depression, and anxiety
Individual Differences
Teratogens
Maternal anxiety and stress
– elevated cortisol levels in mothers likely affect the
development of the fetal brain & HPA axis, making it
more susceptible even to mild stresses later in life
– effective interventions include behavioral stress
reduction (e.g., meditation, hypnosis) and… eating
chocolate!
Individual Differences
Teratogens
AIDS
– proportion of infants who contract AIDS prenatally
ranges from 15 (Europe and North America) to 30%
(Africa)
– may contribute to low birthweight, but difficult to
separate its effects from the effects of other risk
factors
– biggest risk comes after birth, when infants begin to
show signs of the disease
Individual Differences
Teratogens
Other toxins
– modern environment is made up of many potentially
harmful chemicals, pollutants, and radiation
– exposure to environmental toxins during pregnancy
has the potential to influence not only the fetus but
possibly the fetus’ children and grandchildren!
Can Birth Defects Be Prevented?
• Many birth defects can be diagnosed prenatally
through genetic counseling & techniques like
amniocentesis
• Treatments include fetal medicine, postnatal
intensive care, and abortion
– abortion is controversial, especially if it is done
because of low income or for family planning
Family and Society
Mothers
• Pregnancy brings many changes
– transition to parenthood is a big shift
– many pregnant U.S. mothers worry about appearance
• Mother & fetus are a unique biological system –
each changes in response to the other
– good nutrition is essential
Family and Society
Mothers
Successful adaptation to pregnancy is related to
– knowledge of pregnancy & childbirth
– the presence of the father
– marital satisfaction
– low levels of family stress
– social support from family and friends
– ability to remain active
– emotional well-being
Family and Society
Fathers
• Fathers often identify with their partners’
changes & act in supportive roles
• Some have difficulties adapting to the pregnancy
– may feel emotionally distant, engage in extramarital
sex, or even abuse (about 1 in 6 women in the U.S.)
– risk for abuse increases with factors such as teenage
pregnancy, low social support, low income, unmarried
status, unplanned pregnancy, drug & alcohol abuse,
and poor prenatal care
Family and Society
Fathers
Adaptation to pregnancy is
supported by
– knowledge of pregnancy &
childbirth
– social support
– marital satisfaction
– low levels of family stress
– emotional well-being
Picture from www.healthcoop.bm
Family and Society
Siblings
• Preparing a first child for the birth of the second
child does not seem to affect the amount of later
sibling rivalry
• Conflict between the mother and
the first child predicts more
interfering behavior of the first
child with the new baby
Picture from www.breastfeeding123.com
On the Web
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www.engenderhealth.org/wh/fp/index.html
www.kencrest.org
www.waisman.wisc.edu/earlyint/pathways
www.babycenter.com
www.childsecure.com
www.birthpsychology.com
www.marchofdimes.com
Experiential Exercises:
Awakening your senses
• Blindfold yourself for a period of at least 3 hours,
preferably up to 24 hours, in a familiar environment
• Go about your various activities to the extent that the
blindfold allows.
• Spend some time noticing features of your environment
that are external to you and spend some time turning
your focus inward and noticing what is happening within
you.
• After doing this, try over the next few days to notice
some of the things that came up for you when you were
wearing the blindfold while now engaging in your typical
activities without the blindfold
Experiential Exercises:
Navel radiation patterns
•
•
Relax on the floor
Observe the movement of your breath and notice where in your
body you can feel the breath going. Can you imagine your breath
going up into your arms and legs; fingers and toes; and up into
your face and head?
Imagine your breath entering through the navel, and radiating
from there to all parts of your body as you inhale As you exhale,
imagine that the breath is flowing out through your navel.
•
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•
•
Keep imagining this movement of the breath until you begin to feel
the flow of energy, carried by the breath, through each limb – from the
navel to the fingers – toes – top of the head – and tail of the spine,
filling as you inhale, then returning back to the center again, emptying
out as you exhale.
Allow the breath to move you – in and out. Begin with small
movements through each limb, extending out and folding back in
to the center with the flow and rhythm of the breath. Gently
explore these movements
Rest & slowly come back to the room. Open your eyes.