Chapter 3 - Prenatal Development, Birth, and the Newborn

Question 1

Define: prenatal development

Answer 1

The changes that transform a fertilized egg into a newborn, takes an average of 38 weeks, divided into three stages.

Question 2

What are the 3 stages of prenatal development and at what point do each occur?

Answer 2

1. The period of the zygote (Weeks 1-2)
2. The period of the embryo (Weeks 3-8)
3. The period of the fetus (Weeks 9-38)

Question 3

Describe the main prenatal developments that occur during the period of the zygote.

Answer 3

The zygote grows rapidly through cell division and travels down the fallopian tube toward the uterus. The period ends when the fertilized egg implants itself in the wall of the uterus.

Question 4

Describe the main prenatal developments that occur during the period of the embryo.

Answer 4

Body structures and internal organs develop.

Question 5

Define: implantation

Answer 5

The blastocyst burrows into the uterine wall and establishes connections with the mother’s blood vessels. Takes about a week to complete and triggers hormonal changes that prevent menstruation, letting the woman know she has conceived.

Question 6

Define: placenta

Answer 6

A structure for exchanging nutrients and wastes between the mother and the developing organism.

Question 7

Define: embryo

Answer 7

The baby from weeks 3-8, after the blastocyst is completely embedded in the uterine wall. Rests in an amniotic sac, which is filled with amniotic fluid that cushions the embryo and maintains a constant temperature.

Question 8

Define: ectoderm

Answer 8

The outer layer of the embryo, will become hair, the outer layer of skin, and the nervous system.

Question 9

Define: mesoderm

Answer 9

The middle layer of the embryo, will form muscles, bones, and the circulatory system.

Question 10

Define: endoderm

Answer 10

The inner layer of the embryo, will form the digestive system and the lungs.

Question 11

Which two structures link the embryo to the mother?

Answer 11

The umbilical cord and the placenta.

Question 12

Define: the umbilical cord

Answer 12

Houses blood vessels that join the embryo to the placenta.

Question 13

At what point in development does the fetus weigh enough for the mother to feel it move?

Answer 13

At about 4 months, roughly 4 to 8 ounces.

Question 14

Define/explain: the age of viability

Answer 14

By 22 to 28 weeks. Most systems function well enough that a fetus born at this time has a chance to survive.

Question 15

What is the average increased calorie intake required of a pregnant woman, to meet the needs of prenatal development?

Answer 15

About 10% to 20%.

Question 16

What are the negative effects to the infant when a pregnant woman does not provide adequate nourishment?

Answer 16

The infant is likely to be born prematurely and to be underweight.

Question 17

What is one main risk factor when mothers do not consume adequate amounts of folic acid?

Answer 17

Their babies are at risk for spina bifida; a disorder in which the embryo’s neural tube does not close properly during the first month of pregnancy.

Question 18

What are the different weight gain expectations for normal, underweight, and overweight pregnant women?

Answer 18

A normal woman should expect to gain between 25 and 35 pounds during pregnancy. An underweight woman may gain as much as 40 pounds. An overweight woman should gain at least 15 pounds.

Question 19

What are the 3 ways chronic stress can harm an infant’s development?

Answer 19

1. 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 level
2. stress can weaken a pregnant woman’s immune system, making her more susceptible to illness, which can, in turn, damage fetal development
3. pregnant women under stress are more likely to smoke or drink alcohol and less likely to rest, exercise, and eat properly

Question 20

Define: teratogen

Answer 20

An agent that causes abnormal prenatal development.

Question 21

What are 5 of the most common diseases that are harmful to developing infants?

Answer 21

AIDS, genital herpes, rubella/German measles, syphillis, Cytomegalovirus/herpes.

Question 22

What are some of the effects of FAS on infants?

Answer 22

-children with FAS usually grow more slowly than normal and have heart problems and misshapen faces, have serious attentional, cognitive, and behavioral problems

Question 23

How does smoking effect the fetus?

Answer 23

Nicotine in cigarette smoke constricts blood vessels and thus reduces the oxygen and nutrients that can reach the fetus through the placenta.

Question 24

What are some examples of drug teratogens?

Answer 24

accutane, alcohol, aspirin, caffeine

Question 25

What are the 5 principles of how teratogens influence prenatal development?

Answer 25

1. The impact of a teratogen depends on the genotype of the organism
   - a substance may be harmful to one species but not to another, ex. thalidomide safe on pregnant rats/rabbits but not humans
2. The impact of teratogens changes over the course of prenatal development.
3. Each teratogen affects a specific aspect (or aspects) of prenatal development
4. The impact of teratogens depends on the dose
   - an implication of this principle is that researchers should be able to determine safe levels for a teratogen, this is very difficult because sensitivity to teratogens will not be the same for all people
5. Damage from teratogens is not always evident at birth, but may appear later in life, ex. cocaine babies had withdrawal right away vs. the drug DES caused cancer later in life
   - the impact of teratogens depends on the genotype of the organism as well as the timing and amount of exposure to the teratogen

Question 26

What are 4 types of prenatal screening/diagnosis?

Answer 26

genetic counselling, ultrasound, cvs, amniocentesis

Question 27

Define/explain: genetic counseling

Answer 27

a counselor constructs a family tree for each prospective parent to check for heritable disorders, if it turns out that one (or both) carries a disorder, further tests can determine the person’s genotype

Question 28

How many different genetic disorders can be detected with samples obtained from either amniocentesis or CVS?

Answer 28

about 200

Question 29

Why is CVS is often preferred over amniocentesis?

Answer 29

Because it can be done about 9 to 12 weeks after conception, nearly 4 to 6 weeks earlier than amniocentesis.

Question 30

Define: chorionic villus sampling (CVS)

Answer 30

a sample of tissue is obtained from the chorion (a part of the placenta) and analyzed

Question 31

Define: ultrasound

Answer 31

A standard part of prenatal care in North America. Procedure that uses sound waves to generate a picture of the fetus. Can be used as early as 4 or 5 weeks after conception.

Question 32

Define: amniocentesis

Answer 32

A needle is inserted through the mother’s abdomen to obtain a sample of the amniotic fluid that surrounds the fetus. Typically performed at approximately 16 weeks after conception.

Question 33

What are the different things an ultrasound can reveal?

Answer 33

gross physical deformities, twins or other multiple pregnancies, the child’s sex

Question 34

Define: fetal medicine

Answer 34

A field of medicine concerned with treating prenatal problems before birth, still highly experimental and therefore considered as a last resort.

Question 35

Define: genetic engineering

Answer 35

Replacing defective genes with synthetic normal genes.

Question 36

Describe the main features of prepared approaches to childbirth.

Answer 36

Prepared childbirth emphasizes education, relaxation, and the presence of a supportive coach, viewing labour and delivery as life events to be celebrated rather than medical procedures to be endured.

Question 37

Define: crowning

Answer 37

The point in labour when the top of the baby’s head appears.

Question 38

Define: breech presentation

Answer 38

Happens in a small percentage of births where the baby comes out feet or bottom first.

Question 39

Define: hypoxia

Answer 39

The flow of blood through the umbilical cord is disrupted, infants do not receive adequate oxygen.

Question 40

Define/explain: cesarean section (C-section)

Answer 40

An incision is made in the abdomen to remove the baby from the uterus. Rriskier for mothers than a vaginal delivery because of increased bleeding and greater danger of infection, poses little risk for babies.

Question 41

Define: premature infants

Answer 41

Born at 35 weeks after conception (or earlier). By age 2 or 3 years, differences in development vanish and most premature infants develop normally thereafter.

Question 42

Explain the 3 stages of labour and what happens during each stage.

Answer 42

In Stage 1, the muscles of the uterus contract, causing the cervix to enlarge, in Stage 2, the baby moves through the birth canal, in Stage 3, the placenta is delivered.

Question 43

List and describe the 4 newborn states.

Answer 43

1. alert inactivity: the baby is calm, with eyes open and attentive; the baby looks as if he is deliberately inspecting his environment.
2. waking activity: the baby’s eyes are open, but they seem unfocused, the baby moves her arms or legs in bursts of uncoordinated motion
3. crying: the baby cries vigorously, usually accompanying this with agitated but uncoordinated motion
4. sleeping: the baby’s eyes are closed and the baby drift s back and forth from periods of regular breathing and stillness to periods of irregular breathing and gentle arm and leg motion

Question 44

Define: sudden infant death syndrome (SIDS

Answer 44

A healthy baby dies suddenly, for no apparent reason, more likely when a baby sleeps on its stomach.

Question 45

Define: co-sleeping

Answer 45

When infants and young children sleep with their parents.

Question 46

Define: reflexes

Answer 46

Unlearned responses that are triggered by a specific form of stimulation.