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CHAPTER 4 PRENATAL DEVELOPMENT AND BIRTH

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Title: CHAPTER 4 PRENATAL DEVELOPMENT AND BIRTH


1
CHAPTER 4PRENATAL DEVELOPMENT AND BIRTH
2
Learning Objectives
  • How does development unfold during the prenatal
    period from conception until the time of birth?
  • What are the developmental milestones of prenatal
    development?

3
Prenatal Development Conception
  • Conception
  • The union of the mature ovum and a sperm
  • The genetic material of the cells unite to form
    a zygote

4
Prenatal Development Infertility
  • Infertility
  • After a year of trying to get pregnant,
    conception does not occur
  • Assisted reproduction technologies (ARTs) are
    used to increase fertility
  • Artificial insemination
  • Sperm injected into a womans uterus
  • In vitro fertilization (IVF)
  • Eggs and sperm combined and then placed in a
    womans uterus

5
Stages of Prenatal Development Germinal Period
  • Lasts approximately 2 weeks
  • Zygote divides through mitosis and forms a
    blastocyst that implants into the blood vessels
    of the uterine wall
  • Only about half of fertilized ova implant
    successfully
  • Between 15-20 of recognized pregnancies
    terminate in miscarriage
  • As many as 50 of unrecognized pregnancies are
    estimated to terminate with miscarriage, probably
    due to genetic defects

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7
Stages of Prenatal Development Embryonic Period
  • From the 3rd week to the 8th week after
    conception
  • Organogenesis
  • Formation of every major organ
  • Brain and spinal cord, heart, facial features,
    limbs
  • Layers of the blastocyst differentiate
  • Sexual differentiation

8
Stages of Prenatal Development Embryonic Period
  • Differentiation of the blastocyst during the
    embryonic period
  • Outer layer becomes the amnion and chorion
  • Amnion - membrane that fills with fluid that
    cushions and protects the embryo
  • Chorion membrane that surrounds the amnion and
    eventually becomes the lining of the placenta
  • Placenta tissue connected to the embryo by the
    umbilical cord
  • Placenta and umbilical cord embryo receives
    oxygen and nutrients and eliminates carbon
    dioxide and metabolic wastes into the mothers
    bloodstream

9
Stages of Prenatal Development Embryonic Period
  • Differentiation of the blastocyst during the
    embryonic period
  • Cells in interior of blastocyst become the
    ectoderm, mesoderm, and endoderm
  • Ectoderm evolves into the central nervous sytem
  • Mesoderm evolves into muscle tissue, cartilage,
    bone, heart, arteries, kidneys, gonads
  • Endoderm gastrointestinal tract, lungs, bladder

10
Stages of Prenatal Development Embryonic Period
  • Neural tube defects during the embryonic period
  • In approximately 1 of 1,000 pregnancies, the
    neural tube fails to close completely
  • Spina bifida part of the spinal cord not fully
    encased in the protective covering of the spinal
    cord
  • Anencephaly the top of the neural tube does not
    close, and the main portion of the brain above
    the brain stem does not develop
  • Neural tube defects occur 25-29 days after
    conception
  • More common when the mother is deficient in folic
    acid

11
Stages of Prenatal Development Embryonic Period
  • Sexual differentiation during the embryonic
    period
  • Undifferentiated tissue becomes ovaries or testes
  • In a genetic male, a gene on the Y chromosome
    directs construction of testes
  • Embryonic testes secrete testosterone that
    stimulates development of the male internal
    reproductive system and a hormone that inhibits
    the development of a female internal reproductive
    system
  • In a genetic female, ovaries form
  • In the absence of hormones, the embryo develops
    the internal reproductive system of a female

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13
Stages of Prenatal Development Fetal Period
  • Lasts from the 9th week of pregnancy until birth
  • Cells proliferate, migrate, and differentiate
  • Differentiation of cells occurs according to
    where cells migrate
  • Organ systems continue to grow and begin to
    function
  • Sex organs appear during 3rd month of pregnancy
  • Age of viability reached at about 23 weeks
  • When survival is possible if the brain and
    respiratory system are sufficiently developed
  • Weight gain
  • Organized and adaptive behaviors develop
  • Patterns of heart rate, activity level

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15
Learning Objectives
  • How and when do various teratogens affect the
    developing fetus?
  • How can you summarize the effects of teratogens
    during the prenatal period?
  • How do maternal age, emotional state, and
    nutrition affect prenatal and neonatal
    development?
  • What about the fathers state - can this
    influence development?

16
Prenatal Environment
  • Reciprocal influences
  • Transactions between the developing organism and
    its physical and social environments
  • Events of the prenatal period have lifelong
    effects on physical health and mental development
  • Transactions between the organism and its
    environment begin at conception

17
  • Caption The critical periods of prenatal
    development

18
Teratogens
  • Any disease, drug, or environmental agent that
    can harm a developing organism
  • Generalizations about the effects of teratogens
  • Critical period effects are worst during the
    critical period when an organ system grows most
    rapidly
  • Dosage and duration the greater the level of
    exposure and the longer the exposure, the more
    likely is serious damage
  • Genetic makeup susceptibility to harm
    influenced by the organisms and its mothers
    genetic makeup
  • Environment effects depend upon the quality of
    both the prenatal and the postnatal environments

19
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21
  • Caption Characteristic features of a child with
    fetal alcohol syndrome (FAS)

22
Illustrations of the Principles of Teratology -
Drugs
  • Thalidomide critical periods for different
    deformities
  • Missing or deformed limbs deformed eyes, ears,
    nose, heart missing ears
  • Tobacco smoking restricts blood flow to the
    fetus and reduces levels of growth factors,
    oxygen, and nutrients that reach the fetus
  • Associated with higher rates of miscarriage
    slower prenatal growth increased risk for
    prematurity, low birth weight, cleft lips and
    palate increased risk of SIDS

23
Illustrations of the Principles of Teratology
Drugs
  • Alcohol
  • Readily crosses the placenta to affect fetal
    development by disrupting the normal process of
    neuronal migration
  • Fetal alcohol syndrome (FAS) most severe
  • FAS children have a smaller head and distinctive
    facial abnormalities FAS children are smaller
    and lag in physical growth compared to age-mates
  • Central nervous system damage

24
Illustrations of the Principles of Teratology-
Alcohol
  • Some children experience milder alcohol-related
    effects as a result of prenatal exposure to
    alcohol
  • Fetal alcohol effects or alcohol-related
    neurodevelopmental disorder
  • Not all features of FAS but have physical,
    behavioral, or cognitive problems, or a
    combination of problems

25
Illustrations of the Principles of Teratology-
Alcohol
  • The effects of alcohol
  • Women who consumer larger quantities are at
    greater risk for children with alcohol-related
    complications
  • Binge-drinking has more negative effects than
    consuming the same number of drinks across
    multiple occasions
  • The effects of alcohol depend upon which systems
    are developing at the time of exposure
  • 1st trimester facial abnormalities
  • 2nd and 3rd trimesters growth and brain
    development are stunted

26
Illustrations of the Principles of Teratology-
Alcohol
  • The effects of alcohol
  • Depend upon the womans physiology how
    efficiently she metabolizes alcohol and how much
    is transmitted to the fetus
  • Depend upon co-occurrence of other factors, such
    as use of cigarettes and other drugs, adequacy of
    prenatal care
  • Depend upon the embryos genetic makeup and
    physical condition and associated ability to
    resist and recover from damage
  • May depend upon direct and indirect paternal
    factors, such as his genetic makeup or quality of
    parenting

27
Illustrations of the Principles of Teratology-
Drugs
  • Cocaine can cause spontaneous abortion, premature
    detachment of the placenta, or fetal stroke
  • Cocaine contributes to fetal malnourishment,
    retarded growth, and low birth weight
  • A small proportion of cocaine-exposed infants
    experience withdrawal-like symptoms at birth
  • Cocaine-exposed infants show deficits on measures
    of information processing and sensory motor
    skills during their first year
  • Most problems caused by prenatal cocaine exposure
    do not persist into childhood

28
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30
Illustrations of the Principles of Teratogens -
Diseases
  • Rubella (German measles) associated with
    blindness, deafness, heart defects, and mental
    retardation in exposed infants
  • Most dangerous during the 1st trimester
  • Damage to the central nervous system, eyes, and
    heart is most likely during the first 8 weeks of
    pregnancy
  • Deafness is likely if the woman contracts rubella
    in weeks 6 to 13 of the pregnancy

31
Illustrations of the Principles of Teratogens -
Diseases
  • Diabetes
  • Gestational diabetes arises during the pregnancy
    and results from elevated blood glucose levels
  • Increased risk of prematurity, stillbirth or
    miscarriage, immature lung development, and large
    fetal size
  • Syphilis sexually transmitted infection
  • Can cause stillbirth or miscarriage
  • Exposed infants may have blindness, deafness,
    heart problems, or brain damage
  • Most damaging in the middle and later stages of
    pregnancy

32
Illustrations of the Principles of Teratogens -
Diseases
  • Acquired immunodeficiency syndrome (AIDS) is
    caused by the human immunodeficiency virus (HIV).
    HIV can be transmitted
  • Prenatally, if the virus passes through the
    placenta
  • Perinatally, by exposure to blood during birth
  • Postnatally, by breast-feeding
  • If HIV-infected pregnant women are not treated,
    approximately 15-35 of infants will be infected

33
Illustrations of the Principles of Teratogens
Environmental Hazards
  • Radiation
  • Doses of radiation used in x-rays and cancer
    treatments are capable of causing mutations,
    spontaneous abortions, and birth defects
  • Pollutants
  • Adverse effects are associated with prenatal
    exposure to air pollution, cigarette smoke, lead,
    and/or mercury

34
The Mothers State Age
  • Very young mothers have higher-than-normal rates
    of birth complications, premature delivery,
    and/or stillbirth
  • Inadequate prenatal care, alcohol use
  • Older women are more likely to experience trouble
    getting pregnant and have an increased risk of
    having miscarriage, stillbirth, or
    low-birth-weight infants
  • Greater chance of multiple pregnancy, which has
    increased risk of fetal mortality

35
The Mothers State Race/Ethnicity
  • Non-Hispanic black women have fetal mortality
    rates that are more than twice the rates
    experienced by other women
  • Non-Hispanic black mothers are more susceptible
    to premature labor
  • Reasons for disparity are not completely
    understood, but include poorer preconception
    health of the mother and less prenatal care

36
The Mothers State Emotional Condition
  • If prolonged and severe emotional stress and
    anxiety are experienced during pregnancy,
    consequences may include
  • Faster and more irregular fetal heart rate,
    stunted prenatal growth, premature birth, birth
    complications
  • Infants whose mothers were highly stressed during
    pregnancy
  • Tend to be smaller, more active, more irritable,
    more prone to crying, and may experience delays
    in cognitive development
  • Also associated with increased risk of developing
    schizophrenia

37
The Mothers State Nutritional Condition
  • Doctors now recommend a well-balanced diet with
    about 300 additional calories per day, with total
    weight gain of 25-35 pounds for normal-weight
    women
  • Depending upon when it occurs, malnutrition can
    result in stillbirths, neural tube defects,
    stunted growth, and cognitive deficits in infancy
    and childhood
  • Folate-enriched cereal products are associated
    with a decrease in the incidence of neural tube
    defects
  • Prenatal vitamins are recommended

38
The Fathers State
  • Fathers age
  • Children born to teenage fathers have increased
    risk of birth complications
  • Children born to older fathers have elevated risk
    of congenital heart defects, neural tube defects,
    and kidney problems
  • Likelihood of Down syndrome is greater when both
    father and mother are older
  • Advanced paternal age (50 and older) is a risk
    factor for schizophrenia

39
  • Caption The three stages of labor Stage 1 (a)
    contractions of the uterus cause dilation and
    effacement of the cervix. (b) transition is
    reached when the frequency and strength of the
    contractions are at their peak and the cervix
    opens completely. Stage 2 ( c) the mother pushes
    with each contraction, forcing the baby down the
    birth canal, and the head appears. (d) Near the
    end of Stage 2, the shoulders emerge and are
    followed quickly by the rest of the babys body.
    Stage 3 (e) with a few final pushes, the
    placenta is delivered.

40
The Fathers State
  • Research limited except for genetic contribution
  • Fathers age can also be influential
  • Over 35 increased number miscarriages, heart
    defects, Down syndrome
  • Over 50 higher risk for schizophrenia
  • Exposure to environmental toxins
  • Radiation, anesthetic gases, pesticides
  • Damage to genetic material in sperm

41
Learning Objectives
  • What is the typical perinatal environment like?
  • What hazards can occur during the birth process?
  • What is the birth experience like from the
    mothers and fathers perspectives, and from
    different cultural perspectives?

42
The Perinatal Environment
  • Modern-day birthing practices
  • Medical setting and use of technology in homelike
    setting
  • Parents want greater flexibility and control,
    especially control over who will assist with the
    delivery
  • Presence of supportive people in the delivery
    room

43
The Perinatal Environment - Childbirth
  • Childbirth is a three-stage process
  • First stage begins with regular uterine
    contractions and ends when the cervix is fully
    dilated (10 centimeters)
  • Second stage is delivery, which begins as the
    fetuss head moves through the cervix into the
    vagina and ends when the baby emerges
  • Third stage is delivery of the placenta

44
The Perinatal Environment Possible Hazards
  • Anoxia shortage of oxygen
  • Anoxia is dangerous because brain cells die if
    they are starved of oxygen for more than a few
    minutes
  • Severe anoxia can cause poor reflexes, seizures,
    heart rate irregularities, breathing
    difficulties, memory impairment, increased risk
    of learning or intellectual disabilities or
    speech difficulties, or cerebral palsy

45
The Perinatal Environment Complicated Delivery
  • If assistance with delivery is necessary, forceps
    or vacuum extraction (suction) may be used
  • Cesarean section is an alternative to normal
    vaginal delivery
  • Used when the baby is too large or the mother is
    too small, the fetus is out of position, when the
    placenta prematurely separates from the uterus,
    or fetal monitoring reveals that a birth
    complication is likely

46
The Perinatal Environment Complicated
Delivery - Cesarean
  • In 2007, 32 of U.S. births were Cesarean
  • Many Cesareans may be unnecessary
  • Reduced liability and more revenue for the
    obstetrician
  • Choose a second Cesarean rather than attempting
    vaginal birth
  • Preference for scheduled birth
  • For optimal outcome for infants, elective
    C-sections should be performed at 39-40 weeks

47
The Perinatal Environment Complicated Delivery
- Medications
  • Laboring women may be given
  • Analgesics and anesthetics to reduce pain
  • Sedatives for relaxation
  • Stimulants to induce or intensify uterine
    contractions
  • Sedatives can cross the placenta to the infant,
    and large doses can make the baby sluggish,
    irritable, difficult to feed or cuddle, and smile
    infrequently

48
The Mothers Experience
  • Birth stories are unique
  • Most women report pain and anxiety, and 77 felt
    the experience was positive
  • Factors that influence the mothers birth
    experience
  • Psychological factors such as her attitude and
    knowledge, sense of control, and social support

49
The Mothers Experience
  • The experience of childbearing is influenced by
    its cultural context
  • The desirability of having children
  • Practices and beliefs about pregnancy and
    delivery
  • In highly industrialized Western societies,
    childbirth is medicalized

50
The Mothers Experience
  • Baby blues 60 of new mothers report a
    relatively mild, quickly resolved state
  • Tearful, moody, irritable, anxious, depressed
  • Postpartum depression 1 in 10 new mothers
    experience a longer-lasting clinical depression
  • Most affected women have histories of depression
  • Additional life stresses and lack of social
    support increase the risk

51
The Mothers Experience Postpartum Depression
  • Research suggests that maternal postpartum
    depression may affect childrens development
  • Less secure attachment
  • Violent behavior
  • Predisposition to later depression
  • Results from maternal behavior that is
    unresponsive, possibly hostile, toward the baby
    tired, distracted, not fully engaged with the
    infant

52
Sibling Adjustment
  • Transition to siblinghood
  • Quality of the microsystem
  • Example strong father-child relationship
  • Exosystem factors
  • Example parents with strong support less
    stressed or tired
  • The childs age, gender, and personality affect
    how the child responds to and adjusts to a new
    sibling
  • Children under age 2 do not show the same
    disruption of mother-child attachment that often
    occurs when older children acquire a new sibling

53
The Fathers Experience
  • Fathers experience both positive and negative
    emotions
  • May experience couvade
  • Physiological symptoms associated with pregnancy
  • Possibly experience symptoms of postpartum
    depression
  • Typically experience postpartum decline in
    marital satisfaction

54
The Fathers Experience
  • Accepted, expected in delivery rooms
  • Attend prenatal classes with wife
  • Experience described as a significant event
  • Anxiety, stress common during delivery
  • Relief, pride, joy when baby is born
  • Sometimes depression following birth
  • Fathers also need support
  • Disappointed if sex does not resume soon

55
Learning Objectives
  • What are the advantages of breast-feeding?
  • Are there disadvantages of breast-feeding?
  • How can at-risk newborns be identified?
  • What treatments are available to optimize
    development of at-risk babies?
  • To what extent are the effects of the prenatal
    and perinatal environments long lasting?
  • What factors influence whether effects are
    lasting?

56
The Neonatal Environment
  • Ideas about parenting and infant care are
    culturally constructed
  • Brazelton Neonatal Behavioral Assessment
  • Newborn assessment technique that assesses infant
    reflexes and infant responses
  • Used to teach parents to understand and
    appreciate their infants

57
The Neonatal Environment
  • Breast or bottle?
  • All major health organizations advocate for
    exclusive breast-feeding for the first 6 months
    of life
  • Health benefits include fewer ear infections and
    respiratory tract problems, stronger lung
    function, and positive effects on immune system
    functioning and weight gain

58
The Neonatal Environment
  • Identifying at-risk newborns
  • Newborns are routinely screened with the Apgar
    test, which is a quick assessment of
  • Heart rate
  • Respiration
  • Color
  • Muscle tone
  • Reflexes

59
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60
The Neonatal EnvironmentIdentifying At-Risk
Newborns
  • Low-birth-weight infants may be born prematurely
    or to term but small for gestational age
  • Prematurity is the leading cause of infant
    mortality
  • Low-birth-weight (LBW) infants are born weighing
    less than 2,500 grams or 5.5 pounds
  • Extremely LBW infants are born weighing less than
    1,000 grams or 2 pounds, 3 ounces
  • Micropreemie infants are born weighing less than
    800 grams or 1.75 pounds

61
The Neonatal EnvironmentIdentifying At-Risk
Newborns
  • Low birth weight is associated with
  • Low socioeconomic status
  • Ethnicity African-American mothers are twice as
    likely to experience premature delivery and LBW
  • Smoking
  • Stress
  • Multiple births

62
The Neonatal EnvironmentIdentifying At-Risk
Newborns
  • LBW and extremely LBW children at risk for
  • Neuro-behavioral problems, including blindness,
    deafness, cerebral palsy, poor academic
    achievement, and autism
  • Respiratory problems as a consequence of
    insufficient surfactant
  • Substance that prevents air sacs of the lungs
    from sticking together

63
The Neonatal EnvironmentIdentifying At-Risk
Newborns
  • Interventions for LBW infants include surfactant
    therapy, breast-feeding, kangaroo care
    (skin-to-skin contact), and massage therapy
  • Long-term outcomes for LBW infants depend upon
  • Their biological condition, specifically their
    health and neurological condition
  • The quality of their postnatal environment
  • Early intervention programs help parents learn to
    provide a growth-enhancing home environment

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65
Risk and Resilience
  • Some infants who are exposed to and affected by
    risks recover from their deficiencies
  • The results of Werners 40-year-long Kauai
    longitudinal study revealed that
  • The effects of prenatal and perinatal
    complications decrease over time
  • The outcomes of early risk depend on the quality
    of the postnatal environment
  • The study also revealed protective factors
  • Personal resources
  • Supportive postnatal environment
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