Chapter 3 - Parental Development, Birth, and the Newborn Flashcards
What is prenatal development?
The changes that transform a fertilized egg into a newborn human
How long is prenatal development?
38 weeks
What are the stages of prenatal development?
1) Period of the Zygote/Germinal stage
2) Period of the Embryo/Embryonic stage
3) Period of the fetus/Fetal period
Period of the Zygote/Germinal Stage: Timespan; Starts; Ends; Milestones; Information
- Timespan: Approx. 2 weeks
- Starts: Fertilization
- Ends: Implantation
- Milestones: Cell division and implantation
- A small cluster of cells near the center of the blastocyst, the germ disc (inner layer), eventually develops into the baby
- The layer closest to the uterus becomes the placenta (outer layer), a structure for exchanging nutrients and waste between the mother and developing organism
What are the steps that occur during the period of the zygote/germinal stage?
1) Ovulation: An egg cell from the ovary enters the fallopian tube
2) Fertilization within 24 hours after ovulation
3) 24-30 hours after fertilization male (sperm) and female (egg) chromosome material unite
4) Egg cell divides for the first time
5) 4 days: A hollow ball of about 100 cells called a blastocyst
6) 4-5 days: Zygote enters the uterus
7) 6-7 days: Zygote begins to attach to the wall of the uterus
8) 12-14 days: Zygote is completely implanted in the uterine wall
Period of the Embryo/Embryonic Period: Timespan; Starts; Ends; Milestones
- Timespan: Approx. 1.5 months
- Starts: At implantation (approx. the 3rd week after conception)
- Ends: After organogenesis (approx. until the end of the 8th week)
- Milestones: Organogenesis and developing amnion (amniotic sac) and chorion (umbilical cord)
At the beginning of the period of the embryo/embryonic period, what layers form in the embryo and what will they form?
1) The outer layer - ectoderm - will become hair, the outer layer of skin, and the nervous system (brain)
2) The middle layer - mesoderm - will form muscles, bones, and the circulatory system (heart)
3) The inner layer - endoderm - will form the digestive system and the lungs
The embryo rests in what?
Amniotic sac
What is the amniotic sac filled with and what does it do?
Amniotic fluid that cushions the embryo and maintains a constant temperature
What does the umbilical cord do?
Houses blood vessels and joins the embryo to the placenta
In the placenta, where do the blood vessels from the umbilical cord run?
Close to the mother’s blood vessels, but not connected to them
Where does blood flow through from the umbilical cord vessels?
Villi
Period of the Fetus/Fetal Period: Timespan; Starts; Ends; Milestones; Information
- Timespan: Approx. 7 months
- Starts: Approx. 9 weeks
- Ends: Birth
- Milestones: Refinement of organ systems and body structures and increased amount of brain development
- By 22 to 28 weeks, most systems function well enough that a fetus born at this time has a chance to survive, which is why this age range is called the age of viability
What occurs during the period of the fetus/fetal period?
- Baby becomes much larger and its bodily systems begin to work
The finishing touches of the nervous, respiratory, and digestive systems are put on the body systems essential to human life - All regions of the brain grow, particularly the cerebral cortex, which regulate many important human behaviours
In general, when is prenatal development most likely to proceed normally for women?
- Between the ages of 20 and 35
- Eat right
- Get good health care
- Free of chronic stress
What are some general risk factors for prenatal development?
1) Nutrition
2) Stress
3) Mother’s age
4) Teratogens
Why is nutrition a general risk factor?
- Mother is the developing child’s sole source of nutrition
- Most pregnant woman need to increase their caloric intake by about 10-20%
- Proteins, vitamins, and minerals are essential (e.g., folic acid is important for the nervous system)
What happens when mothers do not consume adequate amounts of folic acid?
Their babies are at risk for spina bifida, a disorder in which the embryo’s neural tube does not close properly during the 1st month of pregnancy, resulting in permanent damage to the spinal cord and nervous system
What happens if a pregnant woman does not provide adequate nourishment?
The infant is likely to be born prematurely and underweight, in addition to being more vulnerable to illness
What is stress?
Refers to a person’s physical and psychological response to threatening or challenging situations
Why is stress a general risk factor?
- Occasional, relatively mild anxiety is not thought to have any harmful consequences for prenatal development, however, increased and non-generalized stress can harm prenatal development in several ways
- Studies typically show that women who report greater anxiety during pregnancy more often give birth early or have babies who weigh less than average
- When women are anxious throughout pregnancy, their children are less able to pay attention as infants and are more prone to behavioural problems as preschoolers
- When a pregnant woman experiences stress, her body secretes hormones that reduce the flow of oxygen to the fetus while increasing its heart rate and activity
- Stress can weaken a pregnant woman’s immune system, making her more susceptible to illness, which can, in turn, damage fetal development
- Pregnant women under stress are more likely to smoke or drink alcohol, and less likely to rest, exercise, and eat properly
Why are teenage women more likely to have problems during pregnancy, labour, and delivery?
- More likely to be economically disadvantaged and do not get food prenatal care because they are unaware of the need and wouldn’t be able to afford it if they did
- Children of teenage mothers generally do less well in school and more often have behavioural problems
What are some of the problems of teenage motherhood?
- Incomplete education
- Poverty
- Marital difficulties
Why do older women usually have more difficulty getting pregnant and are less likely to have successful pregnancies?
- Past the age of 35, the risks of miscarriage and stillbirth increase rapidly
- Women in their 40s are more liable to give birth to babies with Down syndrome
Why are older women quite effective as mothers?
They are just as able to provide the sort of sensitive, responsive caregiving that promotes a child’s development
What is a teratogen?
An agent that causes abnormal prenatal development
What can teratogens lead to?
- Limbs not developing properly
- Brain damage
- Psychological problems
What are some teratogenic diseases?
- Aids/HIV
- Cytomegalovirus (type of herpes)
- Genital herpes
- Rubella (German measles)
- Syphilis
- Toxoplasmosis
What are the potential consequences and means of transmission for aids/HIV?
- Frequent infections; neurological disorders; death; cognitive delays
- Through the placenta and during passage through the birth canal
What are the potential consequences and means of transmission for cytomegalovirus?
- Deafness, blindness, abnormally small head, cognitive impairments
- Through the placenta to attack the embryo or fetus directly
What are the potential consequences and means of transmission for genital herpes?
- Encephalitis, enlarged spleen, improper blood clotting
- Attacks at birth: The virus is present in the lining of the birth canal and the baby is infected as it passes through to be born
What are the potential consequences and means of transmission for rubella?
- Cognitive impairments, damage to eyes, ears, and heart
- Through the placenta to attack the embryo or fetus directly
What are the potential consequences and means of transmission for syphpilis?
- Damage to the CNS, teeth, and bones
- Through the placenta to attack the embryo or fetus directly
What are the potential consequences and means of transmission for toxoplasmosis?
- Brain and eye damage
- By parasites living in animals
What is the only way to guarantee that diseases do not harm prenatal development?
Women not contracting the disease before or during pregnancy
What are some teratogenic drugs?
- Alcohol
- Aspirin
- Caffeine
- Cocaine and heroin
- Marijuana
- Nicotine
What are some potential consequences of alcohol?
- Fetal alcohol syndrome (fetal alcohol spectrum disorder)
- Cognitive deficits
- Heart damage
- Slowed growth
- Often have a thin upper lip, a short nose, widely spaced eyes, and microcephaly (small head)
What are some potential consequences of aspirin?
Deficits in intelligence, attention, and motor skills
What are some potential consequences of caffeine?
- Low birth weight
- Decreased muscle tone
What are some potential consequences of cocaine and heroin?
- Slowed growth
- Irritability in newborns
- Poor motor development
- Withdrawal
What are some potential consequences of marijuana?
- Lower birth weight
- Less motor control
What are some potential consequences of nicotine?
- Slowed growth
- Possible cognitive impairments
- Constricts blood vessels and inhibits hemoglobin in the blood, thereby reducing oxygen and nutrients that can reach the fetus through the placenta
What are the five important general principles about how teratogens usually work?
1) The impact of a teratogen depends on the genotype of the organism
2) The impact of teratogens changes over the course of prenatal development
3) Each teratogen affects a specific aspect of prenatal development
4) The impact of teratogens depends on the dose
5) Damage from teratogens is not always evident at birth but may appear later
During the period of the zygote, what does exposure to teratogens usually result in?
Spontaneous abortion of the fertilized egg
During the period of the embryo, what does exposure to teratogens usually result in?
Major defects in the body structure
During the period of the fetus, what does exposure to teratogens usually result in?
Either produces minor defects in body structure or causes body systems to function improperly
When a genetic disorder is suspected, what two techniques are usually used?
Amniocentesis and chorionic villus sampling (CVS)
How many genetic disorders can be detected with samples obtained from either amniocentesis or CVS?
200
Although amniocentesis and CVS are virtually error free, what are their downsides?
More likely to cause miscarriages
How is an amniocentesis performed?
A needle is inserted through the mother’s abdomen to obtain a sample of the amniotic fluid that surrounds the fetus
- Ultrasound is used to guide the needle into the uterus
What does amniotic fluid contain and how does it contribute to determining genetic disorders?
Skin cells that can be grown in laboratory dishes and analyzed to determine the genotype of the fetus
When are amniocentesis’ typically performed?
Approximately 16 weeks after conception when the amniotic sac is large enough to provide easy access to the amniotic fluid
When are the results from an amniocentesis usually returned and why?
About 2 weeks later because genetic material can’t be evaluated until enough cells have reproduced for analysis
How is chorionic villus sampling (CVS) performed?
A small tube is inserted through the vagina and into the uterus, and is used to collect a small plug of cells from the placenta
When is CVS typically performed?
About 10 to 12 weeks after conception, which is why it is often preferred over amniocentesis
When are the results from chorionic villus sampling usually returned?
About 7 to 10 days later
What stages are labour usually divided into?
1) Effacement (cervix flattens and thins) and dilation (cervix widens)
2) Delivery of the child
3) Expulsion of the placenta (afterbirth)
What happens during effacement and dilation?
- Begins when the muscles of the uterus start to contract which forces amniotic fluid up against the cervix, opening at the bottom of the uterus that is the entryway to the birth canal
- The wavelike motion of the amniotic fluid with each contraction causes the cervix to enlarge gradually
- Lasts 12-24 hours
- When the cervix is fully enlarged to 10 cm, the second stage of labour begins
What happens during the delivery of the child?
- Pushing the baby along with uterine contractions propels the baby down the birth canal
- Soon the top of the baby’s head appears (crowning)
- Lasts 1 hour
- Most babies arrive head first, but a small percentage of babies come out feet first (breech presentation)
- The baby’s birth marks the end of the second stage of labour
What happens during the expulsion of the placenta?
- Placenta becomes detached from the wall of the uterus and contractions force it out through the birth canal
- Typically lasts 10-15 minutes
When are premature infants born?
Less than 38 weeks after conception
What are small-for-date infants?
Infants who are substantially smaller than would be expected based on the length of time since conception
What can early labour contributing to low birth weight include?
- Being pregnant with twins
- Having a disease
- Being malnourished
- Complications
What weight (g) is considered to be a low birthweight?
< 2,500 g
What weight (g) is considered to be a very low birthweight?
< 1,500 g
What weight (g) is considered to be an extremely low birthweight?
< 1,000 g
What respiratory problems can pre-term infants have?
- Lack chemical called surfactant which is needed for the lungs to fill up properly - synthetic surfactant can be administered to treat pre-term, low birthweight babies
- Can develop respiratory distress syndrome
How can health professionals assess a newborn?
Apgar scale and/or Neonatal behavioural assessment scale (NBAS)
What does an Apgar test do?
Provides a quick, approximate assessment of the newborn’s status by focusing on the body systems needed to sustain life
What key vital signs are looked at on the Apgar scale?
1) Breathing
2) Heart beat
3) Muscle tone
4) Presence of reflex
5) Skin tone
How is the Apgar scale scored?
- Each of the 5 vital signs receives a score of 0, 1, or 2 (2 is optimal)
- Five scores are added together
What does an Apgar score of at least 7 indicate?
The baby is in good physical condition
What does an Apgar score between 4 to 6 indicate?
The newborn will need some special attention and care
What does an Apgar scale of 3 or less indicate?
A life-threatening situation that requires emergency medical care
Apgar points (0-2): Activity
0 - No movement; muscles flaccid
1 - Baby moves limbs slightly
2 - Baby moves limbs actively
Apgar points (0-2): Pulse
0 - Not detectable
1 - Fewer than 100 beats per minute
2 - 100 beats or more per minute
Apgar points (0-2): Grimaces (response to irritating stimulus)
0 - Baby does not respond
1 - Baby grimaces or cries
2 - Baby cries intensely
Apgar points (0-2): Appearance (skin colour)
0 - Baby is blue-gray, pale all over
1 - Normal colour except for extremities
2 - Normal colour all over
Apgar points (0-2): Respiration
0 - No breathing
1 - Slow, irregular breathing
2 - Strong breathing and crying
What is the NBAS?
The neonatal behavioural assessment scale is a comprehensive assessment used with newborns to 2-month old’s to provide a detailed portrait of the baby’s behavioural repertoire
How many behavioural items and test reflexes does the NBAS test?
28; 18
What is the baby’s NBAS performance used to evaluate?
The autonomic, motor, state, and social system
