Prenatal Development

1
Prenatal Development

• Germination
• Stages of Prenatal Development
• Genetics
• Inherited Diseases
• Neonates

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Germination

• Humans start off as a single cell organism
• Gametes The male/female reproductive cells
• Zygote Formed an hour after the sperm enters
• the ovum when the two gametes fuse
• Genes Blueprints for creating a person
• 25,000 of them
• Composed of DNA molecules
• __________________________________________________
  _____________
• Deoxyribonucleic Acid (DNA)
• Located along 46 chromosomes which are organized
  in 23 pairs.
• Each parent provides 23 chromosomes.
• Possible combinations are limitless.
• Nearly all of the cells of the body will contain
• the same 46 chromosomes as the zygote.

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Prenatal Development

• Typically divided into Trimesters
• First Conception to 3 months
• Second 3 to 6 months
• Third 6 to 9 months
• The division of pregnancy into trimesters is
  arbitrary and has no significance with regard to
  prenatal development.

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Prenatal Development

• Conception
• Occurs the moment a sperm cell fertilizes the
  ovum (egg cell), forming a single-celled zygote.

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Prenatal Development

• Three Stages of Prenatal Development
• Germinal (2 weeks)
• Begins with conception.
• Takes place in one of the fallopian tubes.
• Zygote travels to the uterus and attaches
• itself to the uterine wall.
• Rapid cell division occurs
• Once the zygote is successfully attached
• the germinal stage is over.
• Embryonic (6 weeks)
• Developing embryo forms all the major body
  systems,
• organs, and structures.
• Lasts from the beginning of week 3 through week
  8.
• Begins when the zygote attaches itself to the
  uterine wall.
• Ends when the first bone cells form.
• 1 inch long and weighs 1/7 of an ounce.
• Embryo already resembles a human being.

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Prenatal Development

• Teratogen (any agent that causes birth defects)
• Drugs (prescription, nonprescription)
• Alcohol, tobacco
• Environmental pollutants
• Infectious diseases
• Nutritional deficiencies
• Maternal stress
• Advanced age of a parent
• Severity of damage to the unborn depends on
• Dose
• Time of exposure
• Genetic susceptibility

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Teratogens and Timing of Their Effects on
Prenatal Development
Zygote Embryonic period (wks)
Fetal Period (wks)
Central nervous system
Heart
Arms
Most serious damage from teratogens in first
2-8 wks
Eyes
Legs
Ears
Teeth
Palate
Period of susceptibility to structural defects
External genitalia
Period of susceptibility to functional defects
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Prenatal Development

• Fetal alcohol syndrome
• Abnormalities in newborn due to mothers heavy
  use of alcohol in pregnancy
• Abnormalities include
• Facial deformities
• Defective limbs, face, heart
• Most are below-average intelligence
• Some are mentally retarded
• Moderate drinkers during pregnancy have babies
  who were less attentive and alert even at 4 years
  of age.

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Prenatal Development

• Maternal smoking can cause
• Respiratory problems
• SIDS
• ADHD
• Low birth weight

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Prenatal Development

• Illegal drugs that harm during pregnancy
• Cocaine (norcocaine)
• Marijuana
• Heroin
• Incompatible blood types (Rh factor)
• Environmental hazards
• exposure to radiation or chemicals
• STDs, HIV infection, AIDS
• Mother to child transmission of HIV is a serious
  issue in Africa today.

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Multiple Births

• Less than 3 of all cases result in twins
• Any more is far less
• Two types of twins
• Monozygotic (Maternal twins) Identical
• Dizygotic (Fraternal) Completely different
  individuals
• Mothers carrying multiple children run a
  higher risk of premature delivery and birth
  complications.

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Is it a boy or a girl?

• 23 matched pairs of chromosomes
• 22 of them copy their pair.
• 23rd chromosome
• Determines sex
• XX females (Two matching, relatively large
  chromosomes)
• XY males
• Female contributes an X chromosome.
• Male can contribute either an X or a Y.
• If the father contributes a Y chromosome then the
  infant will be male.
• Father who determines the sex of the child.

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Genetics

• Genetics and Traits
• Dominant
• Expressed trait when two competing traits are
  present.
• Recessive
• Trait within an organism that is present, but is
  not expressed.
• Examples Eye color, skin tone, and cleft pallet
• Genotype
• Underlying combination of genetic material
  present.
• Not physically visible
• Phenotype
• Observable trait
• The trait that is actually seen.

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Genetics

• Homozygous
• Inheriting from parents similar genes for a given
  trait.
• Heterozygous
• Inheriting from parents different forms of a gene
  for a given trait.
• Polygenic inheritance
• Inheritance in which combination of multiple gene
  pairs is responsible for the production of a
  particular trait.
• X-linked genes
• Genes that are considered recessive and located
  only on the x chromosome.

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Human Genome Project

• Reached in 2001
• When molecular biologists succeeded
• in mapping the specific sequence of
• genes on each chromosome.
• Most important moment in the history
• of genetics.
• Discovered that 99.9 of the gene
• sequence is shared by all humans.
• Behavioral Genetics Studies the effects
• of heredity on behavior and psychological
• characteristics

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Inherited Diseases

• Down Syndrome
• Disorder produced by the presence.
• of an extra chromosome on the 21st pair.
• Most frequent cause of mental retardation.
• Fragile X Syndrome
• Produced by injury to a gene on the
• X chromosome.
• Producing mild to moderate
• mental retardation.

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Inherited Diseases

• Sickle-cell Anemia
• Blood disorder
• Gets its name from the shape of the red blood
  cells.
• Symptoms Poor appetite, stunted growth, swollen
  stomach, and yellowish eyes.
• Most sever form of the disease
• rarely live beyond childhood.
• Affects one African-American in 400.

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Inherited Diseases

• Tay - Sachs Disease
• Produces blindness and muscle
• degeneration prior to death
• No treatment.
• Usually causes death before its victims reach
  school age.
• Klinefelters Syndrome
• Presence of an extra x chromosome.
• Produces underdeveloped genitals,
• extreme height, and enlarged breasts.

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Inherited Diseases

• Genetic Counseling
• Discipline that focuses on helping people deal
  with issues relating to inherited disorders.

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Prenatal Testing

• Ultrasound Sonography
• High-frequency sound waves scan the
• mothers womb to produce an image of
• the unborn baby.
• Size and shape can be addressed.
• Chorionic villus sampling (CVS)
• Finds genetic defects.
• Involves taking samples of hair like
• material that surrounds the embryo.

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Prenatal Testing

• Amniocentesis
• Identifies genetic defects
• Examines a small sample of fetal cells
• drawn by a needle.
• Inserted into the amniotic fluid surrounding
• the unborn fetus.
• 15-20 weeks into pregnancy.
• Nearly 100 percent accurate.
• Fetal Blood sampling (FBS)
• After 18 weeks of pregnancy.
• Collects a small amount of blood from
• the umbilical cord.
• Detects Down syndrome and most other
• chromosome abnormalities.

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Neonates

• Labor The Process of Birth Begins
• Oxytocin
• Released by the mothers pituitary gland.
• When the concentration of oxytocin is high
  enough, mothers uterus begins periodic
  contractions.
• Braxton-Hicks Contractions (After 4th month)
• False labor
• Contractions will eventually get strong enough to
  force the fetus down the birth canal until the
  baby enters the world.
• Cone-head (Dont Panic!)

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NeonatesThe Stages of Labor

• Most labors take 16-24 hours for firstborn
  children.
• Duration of labor can vary depending on mothers
• Age
• Race
• Ethnicity
• Number of prior pregnancies

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NeonatesThe Stages of Labor

• Stage 1 (Longest stage)
• Uterine contractions every 8-10 minutes
• Last 30 seconds
• Toward the end contractions occur every 2 minutes
• Last 2 minutes
• As the contractions increase the cervix
  (separates uterus from the vagina) becomes
  wider
• Eventually expanding to allow the babys head to
  pass through
• Transition Final part of the first stage
• Fully opened cervix is usually around 10cm
• Stage 2 (Approx. 90 min)
• Episiotomy Incision made to increase the size of
  the vagina to help in stretching
• Is it ethical?
• Babys head emerges from the mother
• Stage ends when the baby has completely left the
  mother
• The placenta is still inside the mother at the
  end of this stage

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NeonatesThe Stages of Labor

• Stage 3 (Quickest stage)
• Expelling of the umbilical cord and placenta
• Lasts just a few minutes
• In most cases once a baby makes it outside they
  spontaneously cry, which helps them to clear
  their lungs of fluid
• If they dont the child may need to be stimulated
  or startled to make it cry
• If it still does not
• Immediate life saving attention may be necessary

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NeonatesApgar Scale

• Rhythm
• Repetitive, cyclical pattern of behavior.
• Important way that behavior can become integrated
  in the neuronal system and aide in the learning
• Circadian Rhythm
• State
• Degree of awareness that an infant displays to
  both internal and external stimulation.
• Alertness, fussing, crying, and different levels
  of sleep.
• How much stimulation is necessary for a reaction

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NeonatesApgar Scale

• Apgar Scale Defined A standard measurement
  system that looks for a variety of indications of
  good health in newborns.
• Evaluates 5 basic qualities
• Appearance (color)
• Pulse (heart rate)
• Grimace (reflex irritability)
• Activity (muscle tone)
• Respiration (respiratory effort)
• Scoring
• From 0-2 on each of the five qualities
• Score total ranges from 0-10
• Prognosis
• Score from 10 down to 8 means that the child is
  fine
• Score from 7 down to 4 will most probably need
  help to start breathing
• Score less than 4 means that the child needs
  immediate life-saving attention

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The Apgar Scale

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NeonatesIf the Child does not Pass the Apgar
Scale

• Average infant weights 7 ½ pounds
• Infant Mortality Death within the first year of
  life
• Anoxia Lack of oxygen
• If lasts longer than a few minutes can cause
  mental retardation
• Stillbirth Delivery of a child who is not alive
• Less than 1 in 100

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NeonatesIf the Child does not Pass the Apgar
Scale

• BIRTH COMPLICATIONS
• Preterm infants (Premature infants) Born prior
  to 38 weeks after conception
• High risk for illness and death.
• Average preterm weighs less than 5 ½ pounds
• Called Low-Birthweight Infants
• High risk for infection and RDS (Respiratory
  Distress Syndrome) because of their lungs have
  not developed completely
• Presents great difficulty in taking in sufficient
  levels of oxygen
• Small-For-Gestational-Age Infants
• Due to delayed fetal growth
• Weigh 90 of the average weight of infants of the
  same gestational age

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NeonatesIf the Child does not Pass the Apgar
Scale

• Very-Low-Birthweight Infants
• Weigh less than 2 ¼ pounds
• Been in womb less than 30 weeks
• Their eyes are fused shut, and earlobes are
  hardly formed
• Their skin is darkened red color
• These infants rarely reach the Age of Viability
• Point at which an infant can survive prematurely
• An infant born earlier than 25 weeks has less
  than a 50-50 chance of survival.
• Postmature Infants Still not born after two
  weeks after the mothers due date
• Blood supply from placenta may become
  insufficient
• Blood supply to the brain may be decreased (brain
  damage)
• Baby may be too large to make it through the
  birth canal

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NeonatesIf the Child does not Pass the Apgar
Scale

• Possible consequences of low birthweight
• Brain injuries
• Lung and liver diseases
• Learning disabilities
• ADHD
• Lower levels in reading and math achievement
• Deficits are evident in adulthood

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NeonatesIf the Child does not Pass the Apgar
Scale

• About 50 of low-birthweight children are
  enrolled in special education programs.
• Low birthweight is linked to asthma.
• Some defects can be improved with
• Early speech therapy
• Intensive enrichment programs
• Kangaroo care and massage therapy

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Postpartum Period

• Lasts about 6 weeks after childbirth when woman
  adjusts physically and psychologically back to
  the prepregnant state.
• Influenced by preceding conditions and
  experiences
• Mother learns to care for the baby, feel good
  about herself and those close to her
• Physical hormone changes, weight loss, return to
  menstruation, loss of energy or fatigue
• Psychological feelings of depression, anxiety,
  coping in new role, excessive worrying

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Percentage of U.S. Women Who Experience
Postpartum Blues and Postpartum Depression
Postpartum blues symptoms appear 2 to 3 days
after delivery and subside within 2 to 3 weeks
No symptoms
Postpartum depression symptoms linger for weeks
or months and interfere with daily functioning