chapter 5 - the period of pregnancy & prenatal development

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    Chapter 5:

    The Period of Pregnancy

    and Prenatal Development

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    The Period of Pregnancy and Prenatal Development

    Chapter Objectives

    To describe the biochemical basis of geneticinformation 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 ofabnormalities

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    The Period of Pregnancy and Prenatal Development

    Chapter Objectives (cont.)

    To trace fetal development through threetrimesters 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.

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    The Period of Pregnancy and Prenatal Development

    Chapter Objectives (cont.)

    To analyze the reciprocity between thepregnant 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, suchas maternal age, drug use, nutrition, and

    environmental toxins

    To examine the impact of culture onpregnancy and childbirth

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    The Period of Pregnancy and Prenatal Development

    Chapter Objectives (cont.)

    To analyze abortion from a psychosocialperspective, including the legal context, its

    social and emotional impact on women, and

    mens views

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    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 humancell can be distinguished from one another.

    In females, this pair is called XX, in males, it is

    called XY

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    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

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    The Period of Pregnancy and Prenatal Development

    Figure 5.1 Diagram of a Small Part of a DNA Molecule

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    The Period of Pregnancy and Prenatal Development

    The Laws of Heredity

    Basic principles of genetics were unknownuntil 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 statesone

    on each chromosome strand in the pair

    Homozygous: both alleles are the same Heterozygous: alleles are different from each

    other

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    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 pairof genes influence a trait (e.g., height)

    Codominance: a pattern of inheritance in

    which both alleles influence the persons

    characteristics Dominance: when one alleles characteristics

    are always observed

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    The Period of Pregnancy and Prenatal Development

    Figure 5.3 Probability of Heterozygous Brown-Eyed Parents ProducingBlue-Eyed Offspring

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    The Period of Pregnancy and Prenatal Development

    Sex-Linked Characteristics

    Gene for specific characteristic is found onthe sex chromosome

    Genetic Sources of Individual Differences Genetic determinants of the rate of

    development

    Genetic determinants of individual traits

    Genetic determinants of abnormal

    development

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    The Period of Pregnancy and Prenatal Development

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    The Period of Pregnancy and Prenatal Development

    Genetic Technology and Psychosocial Evolution

    Today, genetic counseling and prenataldiagnosis 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 childdecide to conceive, several prenatal

    diagnostic methods and medical procedures

    that permit detection of problems before birth

    are available

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    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 onintelligence through the study of family

    relationships

    The Reaction Range

    A range of possible responses to environmental

    conditions, the limits of which are determined by

    ones genotype

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    The Period of Pregnancy and Prenatal Development

    Twins

    The zygote is the cell produced when thesperm 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

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    The Period of Pregnancy and Prenatal Development

    Infertility and Alternative Means of Reproduction

    Chances of experiencing infertility advancewith age

    Infertility may place great stress on a

    marriage

    Artificial insemination is the injection of donor

    sperm into the womans vagina to promote

    conception

    In Vitro fertilization is fertilization in an artificialenvironment or a Test tube baby. Fertilized

    in a petri dish, a zygote is then implanted into

    the mothers uterus

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    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 womans

    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 isthen transferred into the uterus of the mother

    Surrogate mother: a woman conceives and

    bears a child for an infertile couple

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    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

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    The Period of Pregnancy and Prenatal Development

    Figure 5.7 Outcome of Assisted Reproductive Technology CyclesUsing Fresh, Nondonor Eggs or Embryos,by Stage: 2001

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    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

    pregnancyAn amniotic sac forms that encloses the

    developing organism in amniotic fluid. It

    provides a cushion for the developing embryo

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    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 developingchild

    During these brief 6 weeks, the most rapid

    prenatal changes take place as thegroundwork 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

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    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

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    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

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    The Period of Pregnancy and Prenatal Development

    Development From the First to Third Trimester:

    The Fetal PeriodAt 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

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    The Period of Pregnancy and Prenatal Development

    Caesarean Delivery

    If natural childbirth is dangerous to the motheror 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

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    The Period of Pregnancy and Prenatal Development

    Infant Mortality

    The number of infants who die during the firstyear 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

    Th P i d f P d P l D l

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    The Period of Pregnancy and Prenatal Development

    Case Study: A Fathers 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 playduring 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?

    Th P i d f P d P l D l

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    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 mothers emotional state

    Fathers involvement during pregnancy and

    childbirth

    Th P i d f P d P t l D l t

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    The Period of Pregnancy and Prenatal Development

    Impact of the Pregnant Woman on the Fetus

    The Impact of Poverty Mothers Age

    Maternal Drug Use

    NicotineAlcohol

    Fetal alcohol syndrome (FAS) refers to a disorder

    in which mental retardation, poor attention, and

    overactivity are typical of children with the disorder

    Th P i d f P d P t l D l t

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    The Period of Pregnancy and Prenatal Development

    Impact of the Pregnant Woman on the Fetus

    (cont.) Caffeine

    Narcotics

    Prescription Drugs

    Obstetric Anesthetics

    Environmental Toxins

    Mothers Diet

    Th P i d f P d P t l D l t

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    The Period of Pregnancy and Prenatal Development

    Figure 5.9 Live Birthrates by Age of Mother, 1960-2000

    Th P i d f P d P t l D l t

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    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 Pregnanc and Prenatal De elopment

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    The Period of Pregnancy and Prenatal Development

    Reactions to Childbirth

    Every society marks the importance ofchildbirth 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 asthey approach the care of their newborn

    The Period of Pregnancy and Prenatal Development

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    The Period of Pregnancy and Prenatal Development

    Applied Topic: Abortion

    The decision to abort reflects the mothersattitude 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 cultures

    attitudes about the moral implication of ending

    a life after conception and the legal principles

    about when the fetus itself has a right to

    societys protection

    The decision to abort is related to its safety,

    accessibility, and expense

    The Period of Pregnancy and Prenatal Development

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    The Period of Pregnancy and Prenatal Development

    Applied Topic: Abortion (cont.)

    The legal context of abortion in the UnitedStates

    The incidence of legal abortions

    The psychosocial impact of abortion

    Mens reactions to abortion

    The Period of Pregnancy and Prenatal Development

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    The Period of Pregnancy and Prenatal Development

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    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, Karens

    mother, Dons mother, and Dons 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 Dons marital relationship be

    influenced by these experiences?

    What are the ethical considerations in this case?

    The Period of Pregnancy and Prenatal Development

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    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 situationdifferently?