Transcript Chapter 5

Chapter 5:
The Period of Pregnancy
and Prenatal Development
The Period of Pregnancy and Prenatal Development
• Chapter Objectives
– To describe the biochemical basis of genetic
information and the process through which
genetic information is transmitted from one
generation to the next
– To identify the contributions of genetic factors
to individuality through their role in controlling
the rate of development, their contributions to
individual traits, and the genetic sources of
abnormalities
The Period of Pregnancy and Prenatal Development
• Chapter Objectives (cont.)
– To trace fetal development through three
trimesters of pregnancy, including an
understanding of critical periods when normal
fetal development can be disrupted
– To describe the birth process and factors that
contribute to infant mortality.
The Period of Pregnancy and Prenatal Development
• Chapter Objectives (cont.)
– To analyze the reciprocity between the
pregnant woman and the developing fetus,
focusing on ways in which pregnancy affects
a childbearing woman and expectant father
and on basic influences on fetal growth, such
as maternal age, drug use, nutrition, and
environmental toxins
– To examine the impact of culture on
pregnancy and childbirth
The Period of Pregnancy and Prenatal Development
• Chapter Objectives (cont.)
– To analyze abortion from a psychosocial
perspective, including the legal context, its
social and emotional impact on women, and
men’s views
The Period of Pregnancy and Prenatal Development
• Genes and Chromosomes as Sources of
Genetic Information
– Chromosomes are rodlike structures visible in
the nucleus, which store and transmit genetic
information.
– There are 23 pairs of chromosomes residing
in each human cell, one is inherited from the
mother and one from the father.
– The 23 pairs of chromosomes in each human
cell can be distinguished from one another.
– In females, this pair is called XX, in males, it is
called XY
The Period of Pregnancy and Prenatal Development
• Genes and Chromosomes as Sources of
Genetic Information (cont.)
– The sex of the new organism is determined by
whether an X-bearing or a Y-bearing sperm
fertilizes the ovum
The Period of Pregnancy and Prenatal Development
Figure 5.1 Diagram of a Small Part of a DNA Molecule
The Period of Pregnancy and Prenatal Development
• The Laws of Heredity
– Basic principles of genetics were unknown
until the mid-nineteenth century, when the
Austrian monk and botanist Gregor Mendel
began a series of experiments with pea plants
in his monastery garden
– Alleles: each gene has at least 2 states—one
on each chromosome strand in the pair
– Homozygous: both alleles are the same
– Heterozygous: alleles are different from each
other
The Period of Pregnancy and Prenatal Development
• Genotype, Phenotype, and Influences of Alleles
– Genotype: genetic information about a trait
– Phenotype: observed characteristic (e.g., eye
color, hair color)
– Cumulative relation: when more than one pair
of genes influence a trait (e.g., height)
– Codominance: a pattern of inheritance in
which both alleles influence the person’s
characteristics
– Dominance: when one alleles’ characteristics
are always observed
The Period of Pregnancy and Prenatal Development
Figure 5.3 Probability of Heterozygous Brown-Eyed Parents Producing
Blue-Eyed Offspring
The Period of Pregnancy and Prenatal Development
• Sex-Linked Characteristics
– Gene for specific characteristic is found on
the sex chromosome
• Genetic Sources of Individual Differences
– Genetic determinants of the rate of
development
– Genetic determinants of individual traits
– Genetic determinants of abnormal
development
The Period of Pregnancy and Prenatal Development
The Period of Pregnancy and Prenatal Development
• Genetic Technology and Psychosocial Evolution
– Today, genetic counseling and prenatal
diagnosis permit people to make informed
decisions about conceiving or carrying a
pregnancy to term
– Genetic counseling helps couples assess
their chances of giving birth to a baby with a
hereditary disorder
– If couples who might bear an abnormal child
decide to conceive, several prenatal
diagnostic methods and medical procedures
that permit detection of problems before birth
are available
The Period of Pregnancy and Prenatal Development
• Evaluating the Contribution of Genetic Factors to
Behavior
– Genetics and Intelligence
• Specific genetic irregularities can cause degrees of
mental retardation
• Understand the influence of genetics on
intelligence through the study of family
relationships
– The Reaction Range
• A range of possible responses to environmental
conditions, the limits of which are determined by
one’s genotype
The Period of Pregnancy and Prenatal Development
• Twins
– The zygote is the cell produced when the
sperm and egg unite and fertilization occurs.
– Monozygotic twins result when a zygote
divides in two and separates resulting in
identical twins
– Dizygotic, or fraternal twins, result when
multiple ovulations and fertilizations occur
The Period of Pregnancy and Prenatal Development
• Infertility and Alternative Means of Reproduction
– Chances of experiencing infertility advance
with age
– Infertility may place great stress on a
marriage
– Artificial insemination is the injection of donor
sperm into the woman’s vagina to promote
conception
– In Vitro fertilization is fertilization in an artificial
environment or a ‘Test tube baby’. Fertilized in
a petri dish, a zygote is then implanted into
the mother’s uterus
The Period of Pregnancy and Prenatal Development
• Infertility and Alternative Means of Reproduction
(cont.)
– Gamete Intrafallopian Transfer (GIFT): Eggs
and sperm are transferred into a woman’s
fallopian tube and normal fertilization can then
occur
– In Vivo Fertilization: fertilization in a living
body. A woman is artificially inseminated with
sperm, once fertilization occurs the zygote is
then transferred into the uterus of the ‘mother’
– Surrogate mother: a woman conceives and
bears a child for an infertile couple
The Period of Pregnancy and Prenatal Development
• Infertility and Alternative Means of Reproduction
(cont.)
– Many legal and ethical questions have arisen
from these alternative means of reproduction
The Period of Pregnancy and Prenatal Development
Figure 5.7 Outcome of Assisted Reproductive Technology Cycles
Using Fresh, Nondonor Eggs or Embryos,by Stage: 2001
The Period of Pregnancy and Prenatal Development
• Development in the First Trimester: The
Germinal and Embryonic Periods
– The Period of the Zygote lasts about 2 weeks,
from fertilization until the tiny mass of cells
drifts down and out of the fallopian tube and
attaches itself to the wall of the uterus
– The period of the embryo lasts from
implantation through the eighth week of
pregnancy
– An amniotic sac forms that encloses the
developing organism in amniotic fluid. It
provides a cushion for the developing embryo
The Period of Pregnancy and Prenatal Development
• Development in the First Trimester: The
Germinal and Embryonic Periods (cont.)
– The placenta is an organ that is newly form
with each pregnancy and expelled at birth.
Nutrients and waste pass through the
placenta from the mother to the developing
child
– During these brief 6 weeks, the most rapid
prenatal changes take place as the
groundwork for all body structures and
internal organs is laid down. During this time
the embryo is sensitive to tetragons or agents
that can produce malformations in the fetus
The Period of Pregnancy and Prenatal Development
• Development in the First Trimester: The
Germinal and Embryonic Periods (cont.)
– Examples of teratogens are viruses,
medicines, alcohol, drugs, and environmental
toxins
The Period of Pregnancy and Prenatal Development
• Development From the First to Third Trimester:
The Fetal Period
– Lasting from the ninth week until the end of
pregnancy, during this longest prenatal
period, the organism begins to increase
rapidly in size
– In the third month, the organs, muscles, and
nervous system start to become organized
and connected.
– Between 17 and 20 weeks, the new being has
grown large enough that its movements can
be felt by the mother
The Period of Pregnancy and Prenatal Development
• Development From the First to Third Trimester:
The Fetal Period
– At the end of the second trimester, many
organs are quite well developed, and a major
milestone is reached in brain development, in
that all the neurons are now in place
The Period of Pregnancy and Prenatal Development
The Period of Pregnancy and Prenatal Development
The Period of Pregnancy and Prenatal Development
• Caesarean Delivery
– If natural childbirth is dangerous to the mother
or the newborn, an alternative is to remove
the baby surgically through an incision in the
uterine wall. For example, in long labor,
breech position, and anoxia
– Today there is debate if Caesarean sections
are too widely used by physicians
The Period of Pregnancy and Prenatal Development
• Infant Mortality
– The number of infants who die during the first
year of life per 1,000 live births during that
year
– In 2002, the U.S. rate was estimated at 7.0
deaths per 1,000 lived births – up from 6.8 in
2001
– Increases in multiple births, low birth weight
(under 2,500 grams), and premature births
(less than 37 weeks) are all associated with
this increase
– Two thirds of infant deaths occur during the
first month after birth
The Period of Pregnancy and Prenatal Development
• Case Study: A Father’s Recollections
– Thought Questions
• Given all the stress of the situation, what might
account for the very positive feelings reported by
Kunjufu at the moment of birth?
• What are some different roles that men can play
during the childbirth process: What roles is Kunjufu
playing?
• What might be some reasons that men do not want
to be present during labor and delivery?
• How do hospital personnel influence the
experiences of fathers during childbirth?
• How might childbirth preparation classes influence
the experiences of fathers during childhood?
The Period of Pregnancy and Prenatal Development
• The Impact of the Fetus on The Pregnant
Woman
– Changes in roles and social status
– Changes in the mother’s emotional state
– Fathers’ involvement during pregnancy and
childbirth
The Period of Pregnancy and Prenatal Development
• Impact of the Pregnant Woman on the Fetus
– The Impact of Poverty
– Mother’s Age
– Maternal Drug Use
– Nicotine
– Alcohol
• Fetal alcohol syndrome (FAS) refers to a disorder
in which mental retardation, poor attention, and
overactivity are typical of children with the disorder
The Period of Pregnancy and Prenatal Development
• Impact of the Pregnant Woman on the Fetus
(cont.)
– Caffeine
– Narcotics
– Prescription Drugs
– Obstetric Anesthetics
– Environmental Toxins
– Mother’s Diet
The Period of Pregnancy and Prenatal Development
Figure 5.9 Live Birthrates by Age of Mother, 1960-2000
The Period of Pregnancy and Prenatal Development
• The Cultural Context
• Reactions to Pregnancy
– Solicitude versus Shame - care, interest, and
help of others versus shame, condemnation,
and secrecy
– Adequacy versus Vulnerability - sign of sexual
prowess and entrance into social status
versus tiring, exhaustion, and lots of work
The Period of Pregnancy and Prenatal Development
• Reactions to Childbirth
– Every society marks the importance of
childbirth in different ways
– Americans focus on safety of the mother and
child, and toward building a sense of
competence in the mother and the father as
they approach the care of their newborn
The Period of Pregnancy and Prenatal Development
• Applied Topic: Abortion
– The decision to abort reflects the mother’s
attitude toward childbirth, her criteria for a
healthy normal child, her age and economic
resources, and her access to a safe means of
ending the pregnancy
– The decision also reflects the culture’s
attitudes about the moral implication of ending
a life after conception and the legal principles
about when the fetus itself has a right to
society’s protection
– The decision to abort is related to its safety,
accessibility, and expense
The Period of Pregnancy and Prenatal Development
• Applied Topic: Abortion (cont.)
– The legal context of abortion in the United
States
– The incidence of legal abortions
– The psychosocial impact of abortion
• Men’s reactions to abortion
The Period of Pregnancy and Prenatal Development
The Period of Pregnancy and Prenatal Development
• Case Study: Karen and Don
– Thought Questions
• Try to put yourself in the roles of the main
characters in this case: Karen, Don, Karen’s
mother, Don’s mother, and Don’s father. How might
you react?
• How does technology enter this case?
• How are the biological, psychological, and societal
systems involved in understanding the issues
faced by Karen and Don?
• How might Karen and Don’s marital relationship be
influenced by these experiences?
• What are the ethical considerations in this case?
The Period of Pregnancy and Prenatal Development
• Case Study: Karen and Don (cont.)
– Thought Questions (cont.)
• In what ways do cultural issues related to
pregnancy, childbirth, and abortion come into play
in this case? How might a couple living in a
different cultural context approach this situation
differently?