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Chapter 4 PRENATAL DEVELOPMENT AND BIRTH

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PRENATAL DEVELOPMENT AND BIRTH FROM CONCEPTION TO BIRTH Phases of Prenatal Development Period of the zygote: conception through implantation Period of the embryo: 3rd ... – PowerPoint PPT presentation

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Title: Chapter 4 PRENATAL DEVELOPMENT AND BIRTH


1
Chapter 4 PRENATAL DEVELOPMENT AND BIRTH
2
FROM CONCEPTION TO BIRTH
  • Phases of Prenatal Development
  • Period of the zygote conception through
    implantation
  • Period of the embryo 3rd-8th week, organ
    formation, heart beat
  • Period of the fetus 9th week-birth

3
THE PERIOD OF THE ZYGOTE
  • Blastocyst 60-80 cells
  • Embryo inner layer of blastocyst
  • Protective/nourishing tissues outer layer
  • Implantation
  • 7-10 days after conception
  • Tapping mothers blood supply through uterine
    wall
  • Only 25 successfully implant

4
  • Figure 4.1 The Period of the Zygote

5
PERIOD OF THE ZYGOTE
  • Blastocyst Support Structures
  • Amnion watertight sac with amniotic fluid
  • Cushioning against blows
  • Temperature regulation
  • Weightless environment for movement
  • Yolk sac early blood cell production
  • Chorion becomes lining of placenta
  • Allantois forms umbilical cord

6
  • Figure 4.2 The embryo and its prenatal
    environment.

7
PERIOD OF THE ZYGOTE
  • Purpose of the Placenta
  • Semipermeable
  • Allowing nutrients and gasses to pass through
  • Blood cells are too large
  • Site of all metabolic transactions sustaining the
    embryo

8
THE PERIOD OF THE EMBRYO
  • Ectoderm (outer layer)
  • Nervous system
  • Skin
  • Hair
  • Mesoderm (middle layer)
  • Muscles
  • Bones
  • Circulatory system

9
THE PERIOD OF THE EMBRYO
  • Endoderm (inner layer)
  • Digestive system
  • Lungs
  • Urinary tract
  • Vital organs (pancreas, liver, etc.)

10
THE PERIOD OF THE EMBRYO
  • Developmental Milestones
  • 3rd week neural tube
  • 4th week heart beat
  • 7th week a rudimentary skeleton
  • 7th-8th weeks sexual development
  • If male, the Y chromosome triggers a reaction to
    produce testes, otherwise ovaries result

11
  • Figure 4.3 A human embryo at 40 days.

12
THE PERIOD OF THE FETUS
  • Third Month
  • Movement cannot yet be felt by mother
  • Digestive system and excretory systems
    functioning
  • Reproductive system contains immature ova or
    sperm cells

13
  • Figure 4.4 Rate of body growth during the fetal
    period. Increase in size is especially dramatic
    from the ninth to the twentieth week. ADAPTED
    FROM MOORE PERSAUD, 1993.

14
THE PERIOD OF THE FETUS
  • Fourth-Sixth Months
  • Sucking, swallowing, breathing
  • Movements felt by mother
  • Heart beat can be heard with stethoscope
  • Sweat glands functioning
  • Vernix protects skin from chapping
  • Lanugo fine hair helps vernix stick to skin
  • Visual and auditory senses are functional

15
THE PERIOD OF THE FETUS
  • Seventh Ninth Months
  • Age of viability - 22-28 weeks survival outside
    the womb is possible
  • Weight is 4 pounds (at end of 7th month)
  • 9th month activity slows, sleep increases
  • Birth occurs

16
  • Table 4.1 Brief Overview of Prenatal Development

17
  • Table 4.1 Brief Overview of Prenatal Development
    (continued)

18
POTENTIAL PROBLEMS IN PRENATAL DEVELOPMENT
  • Teratogen any agent that can harm an embryo or
    fetus
  • Effects of teratogens
  • Most serious when structure is forming
  • Susceptibility to harm is influenced by genetic
    makeup of mother and embryo
  • Same defect can be caused by different teratogens

19
POTENTIAL PROBLEMS IN PRENATAL DEVELOPMENT
  • Effects of teratogens, continued
  • One teratogen can cause different defects
  • Longer exposure/higher dose, more harm
  • Fathers exposure may affect embryo
  • Long-term effects depend on postnatal environment
  • Some effects not apparent until later in life

20
  • Figure 4.5 The critical periods of prenatal
    development. Each organ or structure has a
    critical period when it is most sensitive to
    damage from teratogens. Dark band indicates the
    most sensitive periods. Light band indicates the
    time that each organ or structure is somewhat
    less sensitive to teratogens, although damage may
    still occur. ADAPTED FROM MOORE PERSAUD, 1993.

21
TERATOGENS
  • Diseases of the pregnant woman
  • Rubella (German measles)
  • Blindness, deafness, cardiac abnormalities,
    mental retardation
  • Most dangerous during 1st trimester
  • No woman should try to conceive unless they have
    had rubella or been immunized

22
TERATOGENS
  • Toxoplasmosis
  • Caused by eating undercooked meat, handling cat
    feces
  • Causes eye and brain damage during first
    trimester
  • Induces miscarriage later in pregnancy

23
  • Table 4.2 Common Diseases That May Affect an
    Embryo, Fetus, or Newborn

24
TERATOGENS
  • Sexually Transmitted Diseases
  • Syphilis
  • Cannot be transmitted to fetus until 18th week
  • Early treatment prevents harm
  • Damages eyes, ears, bone, heart, brain
  • Can result in miscarriage

25
TERATOGENS
  • Sexually Transmitted Diseases
  • Genital Herpes
  • Can cross placenta
  • Most infections occur during birth
  • Kills 33 of infected newborns
  • Causes blindness, brain damage and other
    neurological problems in 25-30
  • Cesarean delivery prevents infecting newborn

26
TERATOGENS
  • Sexually Transmitted Diseases
  • Acquired Immunodeficiency Syndrome (AIDS)
  • Caused by HIV
  • Passed through placenta, while giving birth, or
    while breast-feeding
  • Only 25 of those at risk are infected
  • ZDV reduces transmission by 70
  • 50 of HIV infected infants live past 6

27
TERATOGENS
  • Drugs
  • Thalidomide
  • Used to prevent nausea and vomiting
  • Tested on animals and was safe
  • Caused birth defects (for some) if taken during
    first 2 months of pregnancy
  • Eyes, ears, noses, hearts
  • Phocomelia parts of limbs missing, feet or
    hands connected to torso

28
TERATOGENS
  • Drugs
  • Aspirin growth retardation, infant death
  • Ibuprofen 3rd trimester pulmonary
    hypertension, prolonged delivery
  • Caffeine miscarriage, low birth weight
  • Lithium 1st trimester heart defects
  • Oral contraceptives heart defects
  • Diethylstilbestrol (DES) delayed effects in
    reproductive system, primarily female

29
TERATOGENS
  • Drugs
  • Alcohol compromises functioning of the placenta
  • Fetal alcohol syndrome (FAS)
  • Microcephaly
  • Malformation of heart, limbs, joints and face
  • Hyperactivity, seizures, tremor
  • Lower IQ, major adjustment problems

30
TERATOGENS
  • Alcohol
  • Fetal Alcohol Effects (FAE)
  • Social drinking (1-3 per day)
  • Greatest risk binge drinking (5)
  • Slow physical growth, poor motor skills,
    attention difficulties, verbal learning
    difficulties
  • Subnormal intellectual performance
  • Fathers drinking may also be harmful

31
TERATOGENS
  • Cigarette Smoking
  • Cleft lip
  • Abnormal lung functioning
  • Miscarriage
  • Low-birth-weight
  • Ectopic pregnancy implantation in fallopian
    tube
  • Sudden Infant Death Syndrome
  • Higher concentration of nicotine in fetus

32
TERATOGENS
  • Marijuana
  • Emotional regulation in males
  • Poorer reading/spelling at 10 years old
  • More depression/anxiety
  • Narcotics (heroin, methadone)
  • 60-80 born addicted
  • Breathing/swallowing coordination
  • Normal developmental progress by age 2, although
    boys remain vulnerable

33
TERATOGENS
  • Cocaine
  • Miscarriage, premature birth
  • Sleep disturbances, very irritable
  • Lower IQ
  • Poor language development skills
  • Negative effects also due to
  • Maternal vocabulary
  • Home environment
  • Exposure to additional teratogens

34
  • Table 4.3 Partial List of Drugs and Treatments
    Used by the Mother That Affect (or Are Thought to
    Affect) the Fetus or the Newborn

35
TERATOGENS
  • Environmental Hazards
  • Radiation death, mental retardation
  • Chemicals/pollutants
  • Lead/mercury deformities, mental retardation
  • PCBs less neurologically mature
  • Prenatal and postnatal effects
  • Fathers exposure also harmful

36
  • Figure 4.6 Average cognitive test performance at
    age nine, based on childs level of exposure to
    PCB prenatally and through breast feeding. Light
    bars indicate children who were exposed to low
    levels of PCB, dark bars are children who were
    exposed to high levels of PCB.

37
MATERNAL CHARACTERISTICS
  • Pregnant Womans Diet
  • Total weight gain 25-35 pounds
  • 1st trimester malnutrition miscarriage, spinal
    cord malformation
  • 3rd trimester malnutrition low-birth-weight,
    small heads
  • Dietary supplements and stimulation can reduce
    effects of prenatal malnutrition

38
  • Figure 4.7 Incidence of infant mortality in the
    first 12 months for babies born to Dutch mothers
    who had experienced famine during World War II.
    ADAPTED FROM STEIN SUSSER, 1976.

39
MATERNAL CHARACTERISTICS
  • Pregnant Womens Diet
  • Magnesium Zinc reduce complications
  • Folic acid reduces Down Syndrome, spina bifida,
    anencephaly
  • Medical supervision is necessary, as excessive
    vitamin/mineral supplements can be harmful

40
MATERNAL CHARACTERISTICS
  • Pregnant Womans Emotional Well-Being
  • Prolonged and severe emotional stress
  • Stunted prenatal growth
  • Premature delivery
  • Irritable
  • Irregular feeding, sleeping
  • Causal relationship in animals

41
  • Figure 4.8 Percent of bath time infants spent
    fussing and crying. The figure compares infants
    whose mothers experienced high levels of cortisol
    (a hormone related to stress) to infants whose
    mothers experienced low levels of cortisol during
    pregnancy.

42
  • Figure 4.8 Percent of bath time infants spent
    fussing and crying. The figure compares infants
    whose mothers experienced high levels of cortisol
    (a hormone related to stress) to infants whose
    mothers experienced low levels of cortisol during
    pregnancy. (continued)

43
MATERNAL CHARACTERISTICS
  • Pregnant Womens Emotional Well Being
  • Prolonged stress
  • Stress hormones impede oxygen and nutrients to
    fetus
  • Weaken immune system
  • Linked to poor eating, smoking, drug and alcohol
    use all harm fetus
  • Counseling to manage/reduce stress
  • Moderate levels may aid development

44
MATERNAL CHARACTERISTICS
  • Pregnant Womans Age 16-35 is optimal
  • 15 years old and younger
  • Impoverished backgrounds
  • Poor nutrition, high stress, little prenatal care
  • Little risk if good prenatal care is present
  • Older than 35
  • Increased risk of miscarriage
  • Risks not reduced by prenatal care

45
BOX 4.1 - FOCUS ON RESEARCH FETAL PROGRAMMING
  • Fetal Programming Theory brain and other
    systems are programmed in a manner that is
    adaptive for the uterine environment
  • Persists at birth, but whats adaptive in the
    uterus may not be after birth
  • Focus is on subtle changes in metabolism,
    endocrine and autonomic functions
  • Result may be increased susceptibility to
    diseases in adulthood, like diabetes

46
PREVENTION OF BIRTH DEFECTS
  • 95 of newborns are normal
  • Many of remaining 5 have minor congenital
    problems that are temporary or correctable
  • Each pregnancy is different
  • Genetic makeup
  • Prenatal environment

47
  • Table 4.4 Reducing Likelihood of Congenital
    Disorders.

48
BIRTH AND THE PERINATAL ENVIRONMENT
  • Perinatal environment environment surrounding
    birth
  • Medications
  • Delivery practices
  • Social environment

49
THE BIRTH PROCESS
  • First stage of labor
  • Contractions 10-15 minutes apart
  • Cervix fully dilates
  • Second stage of labor delivery
  • Head passes through cervix
  • Baby emerges from body
  • Third stage of labor afterbirth
  • Placenta expelled from body

50
  • Figure 4.9 The three stages of childbirth.

51
THE BABYS EXPERIENCE
  • Stressful, but assists with breathing
  • Babys Appearance - 20 inches long, 7-7.5
    pounds, bluish, a bit misshapen
  • Assessing the Babys Condition
  • Apgar test
  • Heart rate, respiratory effort, muscle tone,
    color, reflex irritability
  • Scored 0-10 (0-2 each)
  • 7 good, 4 and lower needs attention

52
  • Table 4.5 The Apgar Test

53
THE BABYS EXPERIENCE
  • Assessing the Babys Condition
  • Neonatal Behavioral Assessment Scale
  • Several days after birth
  • 20 inborn reflexes
  • Reactions to comforting and social stimuli
  • Unresponsiveness may indicate neurological
    problems
  • Can be a parent teaching tool

54
LABOR AND DELIVERY MEDICATION
  • Some medication used by 95 of mothers
  • Reduce pain, induce contractions, relax the
    mother
  • Can reduce the ability to push effectively
  • Can make babies lethargic and inattentive
  • Drugs in appropriate doses can increase comfort
    without disrupting delivery

55
BOX 4.2 APPLYING RESEARCH TO YOUR LIFE
VARIATIONS IN BIRTHING PRACTICES
  • Pokot of Kenya community celebration
  • Uttar Predesh in India shameful, disgusting
  • U.S. typically a hospital procedure
  • Natural / prepared childbirth focus is on
    support, relaxation reduces medication
  • Home births shorter labors, less meds, safe if
    smooth pregnancy, trained midwife
  • Alternative birthing centers homelike setting
    in hospital

56
THE SOCIAL ENVIRONMENT SURROUNDING BIRTH
  • Mothers experience
  • First 6-12 hours sensitive period for emotional
    bonding (not essential)
  • Maternity blues 40-60 of mothers
  • Postpartum depression 10 of mothers
  • Should seek professional help
  • Depression affects outcomes of both mother and
    infant

57
THE SOCIAL ENVIRONMENT SURROUNDING BIRTH
  • The Fathers experience
  • Engrossment intense fascination, desire to
    touch, hold and caress
  • Early contact with newborn can make father feel
    closer to partner, positive support for mother

58
POTENTIAL PROBLEMS AT BIRTH
  • Anoxia oxygen deprivation
  • Umbilical cord becomes tangled
  • Breech position
  • Placenta separation
  • RH factor incompatibility now preventable
  • Can cause neurological damage, permanent
    disabilities
  • Increased risk of adult heart disease

59
POTENTIAL PROBLEMS AT BIRTH
  • Complications of Low Birth Weight
  • Preterm born more than 3 weeks early, but
    appropriate weight for time in womb
  • Small for date underweight due to slow fetal
    growth greater risk than preterm
  • Causes include smoking, drug use, stress, lack of
    prenatal care, multiple births, social support

60
  • Figure 4.10. Gestational age at birth for
    singletons, twins, and triplets.

61
POTENTIAL PROBLEMS AT BIRTH
  • Short-term Consequences of Low Birth Weight
  • 40-50 weighing less than 2.2 pounds die
  • Brain development and neural pattern formation in
    preterm infants differs
  • Breathing difficulty due to lack of surfactin, or
    respiratory distress syndrome
  • Spend time in isolettes
  • Can be frustrating to care for

62
POTENTIAL PROBLEMS AT BIRTH
  • Interventions for Preterm Infants
  • Early acquaintance programs touching, rocking,
    talking, are developmentally beneficial
  • Parents can be taught how to be sensitive and
    responsive to preterm infants
  • Combined with stimulating day care programs help,
    improves cognitive growth and reduces behavioral
    disturbances

63
POTENTIAL PROBLEMS AT BIRTH
  • Long-term Consequences of Low Birth Weight
  • Depends on postnatal environment
  • Stimulating home, very good
  • Less stable home or being economically
    disadvantaged
  • Smaller, emotional problems
  • Deficits in intellectual/academic performance

64
  • Figure 4.11. Age trends in intellectual
    development for low-birth-weight twins from
    middle-class (high SES) and lower socioeconomic
    (low SES) backgrounds. ADAPTED FROM WILSON, 1985.

65
REPRODUCTIVE RISK AND CAPACITY FOR RECOVERY
  • Werner Smith Kauai Longitudinal Study
  • At birth,
  • 16 severe complications, 31 mild
  • Age 2 severity predicted developmental
    progress, but emotional support and educational
    stimulation improved outcomes
  • Age 10 severity not very predictive, home
    environment now predictive

66
APPLYING DEVELOPMENTAL THEMES TO PRENATAL
DEVELOPMENT AND BIRTH
  • Active child moves, practices in womb
  • Nature/nurture interaction effects of
    teratogens
  • Qualitative changes stages of birth
  • Quantitative changes fetal development
  • Holistic nature of development prenatal
    development affects all future development
    social support during birth has consequences for
    future development
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