Post on 09-May-2020
WHAT WILL YOU KNOW?
When do the most important parts of the fetus form?
Does medical assistance safeguard or impede the birth process?
What usually occurs in the first few minutes of a newborn’s life?
Why do substances and circumstances sometimes harm the fetus and sometimes have no impact.
What are the immediate and long-term causes and consequences of low birthweight?
Why do some mothers suffer from postpartum depression, and how does that affect the baby?
Prenatal Growth
Three main periods of prenatal development
Germinal period
Embryonic period
Fetal period
Prenatal Growth
Can you define these terms related to
timing and technology?
Beginning of pregnancy
Length of pregnancy
Trimesters
Due date
Vulnerability During Prenatal Development
The Germinal Period (First 14 Days)
• About half of all conceptions fail to grow or implant properly and thus do not survive the germinal period. Most of these organisms are grossly abnormal.
The Embryonic Period (From Third Through Eighth Week)
• About 20 percent of all embryos are aborted spontaneously,** most often because of chromosomal abnormalities.
The Fetal Period (From Ninth Week Until Birth)
• About 5 percent of all fetuses are aborted spontaneously before viability at 22 weeks or are stillborn (defined as born dead after 22 weeks).
Birth
• About 31 percent of all zygotes grow and survive to become living newborn babies.
Germinal Period: First 14 Days
Zygote begins
duplication and division
within hours of
conception.
• Development of the
placenta
• Implantation (about 10
days after conception)
• Organism grows
rapidly
The Most Dangerous Journey
In the first 10 days after conception,
the organism does not increase in
size because it is not yet nourished
by the mother.
The Embryonic Period: From the Third
Through Eighth Week
Embryo
Primitive streak becomes the neural tube and
later forms the brain and spine of the CNS.
Head takes shape.
Eyes, ears, nose, and mouth form.
Heart begins to pulsate.
Extremities develop and webbed fingers and
toes separate.
The Embryonic Period
(a) 4 weeks past conception (b) 7 weeks
Fetus: From Ninth
Week Until Birth
The third month
–Rapid growth with
considerable variation
–Average: 3 months; 3
ounces; 3 inches
–9th week: SRY gene
triggers develop of sex
organs
–3rd month: Neurological
sex differences begin
Fetus: The Middle
Three Months
Middle three months
Digestive and excretory
system develop
Fingernails, toenails, and
buds for teeth form, and hair
grows (including eyelashes)
Fetus: The Middle Three Months
Brain
Experiences rapid growth
Follows proximodistal sequence from brainstem to
midbrain, to cortex
Develops many new neurons (neurogenesis) and
synapses (synaptogenesis)
Begins to regulate basic bodily functions as entire
CNS becomes responsive
Fetus: The Middle Three Months
Age of viability
•Age at which a preterm newborn may survive
outside the mother's uterus if medical care is
available
•About 22 weeks after conception
•Brain is able to regulate basic body functions
(e.g., breathing)
Fetus: The Final
Three Months
Last three months
Involves expansion and
contraction of lungs
Includes final maturation
of heart valves, arteries,
and veins
Provides time for
extensive growth and
folding in cortex
One of the Tiniest
Rumaisa Rahman was born after 26
weeks and 6 days weighing only 8.6
ounces (244 grams). She has a good
chance of living a full, normal life.
Prenatal Growth of the Brain
Birth
Fetal brain signals the release of hormones to trigger the female's uterine muscles.
Labor begins
• Average duration for firstborn babies: 12 hours
• Quicker labor for later-born babies
Birthing positions vary
• Sitting, squatting, lying down, water births
• Cultural and personal preference
A Normal, Uncomplicated Birth
The Newborn’s First Minutes
Newborns
Usually cry spontaneously
Color changes from bluish to pinkish
Eyes open, fingers grab, toes stretch
Newborn mortality = 1 in 250 in U.S.
Apgar scale
Quick assessment of newborn's heart rate, breathing, muscle tone, color, and reflexes
Completed twice (1 minute and 5 minutes after birth)
Score of 0, 1, or 2 in each category
Desired score: 7 or above
Criteria and Scoring of the Apgar Scale
Score Color Heartbeat Reflex
Irritability
Muscle
Tone
Respiratory
Effort
0 Blue, pale Absent No
response
Flaccid,
limp
Absent
1 Body pink,
extremities
blue
Slow
(below
100)
Grimace Weak,
inactive
Irregular, slow
2 Entirely
pink
Rapid
(over 100)
Coughing,
sneezing,
crying
Strong,
active
Good; baby is
crying
Medical Assistance
Characteristics of childbirth depend on several variables– Parents’ preparation
– Position and size of fetus
– Customs of culture
In most developed nations childbirth includes– Sterile procedures
– Electronic monitoring
– Drugs to dull pain or speed contractions
Medical Assistance
Surgery: Cesareans
• Are controversial
• Involve surgical birth
• Vary by rates and reasons for use
• Present advantages for hospitals; more
complications after birth
Too Many Cesareans or Too Few?
Rates of cesarean deliveries vary widely from nation to nation.
Latin America has the highest rates in the world (note that 40 percent of all births in Chile are by cesarean), and sub-Saharan Africa has the lowest (the rate in Chad is less than half of 1 percent).
The underlying issue is whether some women who should have cesareans do not get them, while other women have unnecessary cesareans.
Birth
Alternatives to hospital technology
Place of birth: Hospital labor room; birthing centers; home
Supports: Doulas
Home Births
Planned home births are more common in many
developed countries.
Almost all babies are born at home in poorer nations.
Some research indicate home births entail risks for the
baby.
Every study finds benefits for the mother.
Key to good choice is being “medically informed”.
What Is a Doula?
Person trained to support laboring woman
Time contractions
Provide encouragement
Do whatever else is helpful
Are particularly helpful for immigrant, low-income, or unpartnered women
Harm to the Fetus
Harmful substances
Prenatal teratogens
• Any agent or condition, including viruses, drugs, and resulting in birth defects or complications
Behavioral teratogens
• Agents and conditions that can harm the prenatal brain, impairing the future child's intellectual and emotional
Risk Analysis Factors
Risk analysis discerns which chances are
worth taking and how risks are minimized.
Critical time
Dose and/or frequency of exposure (Threshold
effect)
Innate vulnerability
Risk Analysis: How Much Is Too Much?
Threshold effect
Certain teratogens are relatively harmless until exposure reaches a certain level.
Thresholds are controversial.
Example: Alcohol consumption
Embryo exposed to heavy drinking can develop fetal alcohol syndrome (FAS).
FAS is more apparent when women are poorly nourished and cigarette smokers.
Risk Analysis: Innate Vulnerability
Genetic vulnerability
•Some zygotes carry genes that make them
vulnerable.
•Male fetuses are more vulnerable to teratogens
than female ones.
Mother’s genes affect the prenatal environment
she provides.
•Neural-tube defects are more common in certain
ethnic groups (e.g., Irish, English, and Egyptian).
Conflicting Advice
Advice from Doctors
Problems
• Provision of potentially
dangerous prescriptions for
pregnant women
• Failure to take time to
understand woman’s life
patterns
Advice from Scientists
Problems
• Provision of contradictory
interpretation of research that
led to opposite message
Internet site usage
• Many Internet sites provided
inadequate or incorrect
information about drug safety
What about the Father?
Indirect influence of risk for adverse birth
outcomes (Misra et al., 2010)
Father’s attitude
Father’s behavior
Relationship between mother and father
Immigrant paradox
What Do We Know?
Prenatal teratogens can cause
Structural problems during embryonic period and
several diseases throughout pregnancy
Behavioral problems and reproductive impairment
later in life
Social response to evidence is
controversial.
Prenatal Diagnosis
Early prenatal care may
Protect fetal growth
Make birth easier
Render parents better able to cope
Provide early recognition of potential problems
Raise anxiety
Present false positives
Trouble Ahead
Low Birthweight
Low birthweight (LBW)
Very low birthweight
(VLBW)
Extremely low birthweight
(ELBW)
PretermSmall for
gestational age (SGA)
Low Birthweight and the Mother
Maternal behavior
•Maternal health and illness
•Maternal drug use before and during
pregnancy
Consequences of Low Birthweight
High risk infants and children
Are later to smile, to hold a bottle, to walk, and to
communicate
Middle childhood, formerly SGA children
Have smaller brain volume
Remember that risk analysis gives odds, not
certainties!
The New Family: The Newborn
Brazelton Neonatal Behavioral
Assessment Scale (NBAS)
Test often administered to newborns that
measures responsiveness and records 46
behaviors, including 20 reflexes
Parents who watch their infant perform on the
NBAS are amazed at the newborn’s responses—
and this fosters early parent–child connection.
The New Family: The Newborn
Newborns seek to protect themselves
with three sets of reflexes
Maintaining oxygen: Breathing, hiccupping,
sneezing
•Maintaining constant body temperature: Crying,
shivering, tucking legs to body, pushing
•Managing feeding: Sucking, rooting, swallowing
The New Family: The Newborn
Other reflexes are not necessary for
survival but signify the state of brain and
body functions.
Babinski reflex
Stepping reflex
Palmar grasping reflex
Moro reflex
New Mothers
About half of all women experience physical problems after birth.
Between 8 and 15% of women experience postpartum depression.
• Feelings of sadness and inadequacy
• Symptoms from baby blues to postpartum psychosis
• May involve struggles with adequate baby care
• Varied causes
New FathersNot only fathers, but the entire social network and culture are crucial influences.
Father's role: Being there• Helping mother stay healthy
• Helping mother manage stress (affects fetus)
• Providing legal acceptance the birth
Couvade
Symptoms of pregnancy and birth experienced by fathers.
Parental Alliance
Involves commitment by
both parents to cooperate in
raising the child
Is especially beneficial when
infant is physically
vulnerable
Family Bonding
Parent-infant bond
• Bonding involves strong, loving connection that
forms as parents hold, examine, and feed the
newborn.
• Early skin-to-skin contact is not essential for
human bonding.