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Chapter 4 PRENATAL DEVELOPMENT AND BIRTH. FROM CONCEPTION TO BIRTH. Phases of Prenatal Development Period of the zygote: conception through implantation Period of the embryo: 3 rd -8 th week, organ formation, heart beat Period of the fetus: 9 th week-birth. THE PERIOD OF THE ZYGOTE.

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Chapter 4 prenatal development and birth

Chapter 4 PRENATAL DEVELOPMENT AND BIRTH


From conception to birth
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


The period of the zygote
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 mother’s blood supply through uterine wall

    • Only 25% successfully implant



Period of the zygote
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



Period of the zygote1
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


The period of the embryo
THE PERIOD OF THE EMBRYO

  • Ectoderm (outer layer)

    • Nervous system

    • Skin

    • Hair

  • Mesoderm (middle layer)

    • Muscles

    • Bones

    • Circulatory system


The period of the embryo1
THE PERIOD OF THE EMBRYO

  • Endoderm (inner layer)

    • Digestive system

    • Lungs

    • Urinary tract

    • Vital organs (pancreas, liver, etc.)


The period of the embryo2
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



The period of the fetus
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



The period of the fetus1
THE PERIOD OF THE FETUS Increase in size is especially dramatic from the ninth to the twentieth week. ADAPTED FROM MOORE & PERSAUD, 1993.

  • 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


The period of the fetus2
THE PERIOD OF THE FETUS Increase in size is especially dramatic from the ninth to the twentieth week. ADAPTED FROM MOORE & PERSAUD, 1993.

  • 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




Potential problems in prenatal development
POTENTIAL PROBLEMS IN PRENATAL DEVELOPMENT Increase in size is especially dramatic from the ninth to the twentieth week. ADAPTED FROM MOORE & PERSAUD, 1993.

  • 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


Potential problems in prenatal development1
POTENTIAL PROBLEMS IN PRENATAL DEVELOPMENT Increase in size is especially dramatic from the ninth to the twentieth week. ADAPTED FROM MOORE & PERSAUD, 1993.

  • Effects of teratogens, continued

    • One teratogen can cause different defects

    • Longer exposure/higher dose, more harm

    • Father’s exposure may affect embryo

    • Long-term effects depend on postnatal environment

    • Some effects not apparent until later in life


  • 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.


Teratogens
TERATOGENS 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.

  • 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


Teratogens1
TERATOGENS 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.

  • Toxoplasmosis –

    • Caused by eating undercooked meat, handling cat feces

    • Causes eye and brain damage during first trimester

    • Induces miscarriage later in pregnancy



Teratogens2
TERATOGENS or Newborn

  • 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


Teratogens3
TERATOGENS or Newborn

  • 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


Teratogens4
TERATOGENS or Newborn

  • 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


Teratogens5
TERATOGENS or Newborn

  • 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


Teratogens6
TERATOGENS or Newborn

  • 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


Teratogens7
TERATOGENS or Newborn

  • 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


Teratogens8
TERATOGENS or Newborn

  • 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

      • Father’s drinking may also be harmful


Teratogens9
TERATOGENS or Newborn

  • 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


Teratogens10
TERATOGENS or Newborn

  • 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


Teratogens11
TERATOGENS or Newborn

  • 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



Teratogens12
TERATOGENS Mother That Affect (or Are Thought to Affect) the Fetus or the Newborn

  • Environmental Hazards

    • Radiation – death, mental retardation

    • Chemicals/pollutants

      • Lead/mercury – deformities, mental retardation

      • PCB’s – less neurologically mature

        • Prenatal and postnatal effects

      • Father’s exposure also harmful



Maternal characteristics
MATERNAL CHARACTERISTICS based on child’s 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.

  • Pregnant Woman’s 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



Maternal characteristics1
MATERNAL CHARACTERISTICS months for babies born to Dutch mothers who had experienced famine during World War II. ADAPTED FROM STEIN & SUSSER, 1976.

  • Pregnant Women’s 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


Maternal characteristics2
MATERNAL CHARACTERISTICS months for babies born to Dutch mothers who had experienced famine during World War II. ADAPTED FROM STEIN & SUSSER, 1976.

  • Pregnant Woman’s Emotional Well-Being

    • Prolonged and severe emotional stress

      • Stunted prenatal growth

      • Premature delivery

      • Irritable

      • Irregular feeding, sleeping

      • Causal relationship in animals




Maternal characteristics3
MATERNAL CHARACTERISTICS 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)

  • Pregnant Women’s 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


Maternal characteristics4
MATERNAL CHARACTERISTICS 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)

  • Pregnant Woman’s 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


Box 4 1 focus on research fetal programming
BOX 4.1 - FOCUS ON RESEARCH: FETAL PROGRAMMING 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)

  • Fetal Programming Theory – brain and other systems are programmed in a manner that is adaptive for the uterine environment

    • Persists at birth, but what’s 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


Prevention of birth defects
PREVENTION OF BIRTH DEFECTS 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)

  • 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



Birth and the perinatal environment
BIRTH AND THE PERINATAL ENVIRONMENT 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)

  • Perinatal environment – environment surrounding birth

    • Medications

    • Delivery practices

    • Social environment


The birth process
THE BIRTH PROCESS 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)

  • 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


  • Figure 4.9 The three stages of childbirth. 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)


The baby s experience
THE BABY’S EXPERIENCE 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)

  • Stressful, but assists with breathing

  • Baby’s Appearance - 20 inches long, 7-7.5 pounds, bluish, a bit misshapen

  • Assessing the Baby’s 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


  • Table 4.5 The Apgar Test 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)


The baby s experience1
THE BABY’S EXPERIENCE 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)

  • Assessing the Baby’s 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


Labor and delivery medication
LABOR AND DELIVERY MEDICATION 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)

  • 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


Box 4 2 applying research to your life variations in birthing practices
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


The social environment surrounding birth
THE SOCIAL ENVIRONMENT SURROUNDING BIRTH BIRTHING PRACTICES

  • Mother’s 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


The social environment surrounding birth1
THE SOCIAL ENVIRONMENT SURROUNDING BIRTH BIRTHING PRACTICES

  • The Father’s 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


Potential problems at birth
POTENTIAL PROBLEMS AT BIRTH BIRTHING PRACTICES

  • 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


Potential problems at birth1
POTENTIAL PROBLEMS AT BIRTH BIRTHING PRACTICES

  • 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


  • [ BIRTHING PRACTICES

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


Potential problems at birth2
POTENTIAL PROBLEMS AT BIRTH BIRTHING PRACTICES

  • 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


Potential problems at birth3
POTENTIAL PROBLEMS AT BIRTH BIRTHING PRACTICES

  • 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


Potential problems at birth4
POTENTIAL PROBLEMS AT BIRTH BIRTHING PRACTICES

  • 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



Reproductive risk and capacity for recovery
REPRODUCTIVE RISK AND CAPACITY FOR RECOVERY low-birth-weight twins from middle-class (high SES) and lower socioeconomic (low SES) backgrounds. ADAPTED FROM WILSON, 1985.

  • 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


Applying developmental themes to prenatal development and birth
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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