Prenatal Development

1
Prenatal Development

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

2
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.

3
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)
1 2 3 4 5 6 7 8 9 16 32 38
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
8
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

10
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.

13
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.

15
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.

21
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
Score 0 1 2
Body Color Blue, pale Body pink, extremities blue Entire body pink
Heartbeat Absent Slow less than 100 beats per min. Fast 100 to 140 beats per min.
Reflex Irritability No response Grimace Coughing, sneezing, crying
Muscle Tone Limp and flaccid Inactive, weak, some flexion of extremities Strong, active motion
Respiratory Effort Breathing for no more than 1 min. Irregular and slow Breathing good with normal crying

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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