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