2. 4. Vulnerability during Prenatal Development
1. Introduction
2. Fact or Fiction?
3. From Zygote to Newborn
4. Vulnerability during Prenatal Development
5. The Birth Process
6. The Newborn
7. Closing Thoughts 2

3. [Video: Prenatal Development and Birth
Introduction
Instruction:
Click to play video
This presentation follows the dramatic and extensive transformations of human prenatal development and the events that surround birth
[Video: Prenatal Development and Birth
Introduction] 3

4. Fact or Fiction? Fiction Fact
1. An embryo is the developing human organism between the third and eighth week after conception.
2. By the end of the third month, the fetus has all of its body parts.
3. Teratogens are only a concern for women who use alcohol and drugs.
Instruction: Click to reveal each question, then the category.
Please note, this page is available to use with a clicker system.
4. All newborn reflexes help a baby survive. 4 4

5. Beginning of pregnancy
What is the timing and terminology of pregnancy?
Popular and professional books use various phrases to segment pregnancy. The following comments may help to clarity the phrases used.
Pregnancy begins at conception, which is also the starting point of gestational age. However, the organism does not become an embryo until about two weeks later, and pregnancy does not affect the woman (and cannot be confirmed by blood or urine testing) until implantation.
Beginning of pregnancy
Length of pregnancy
Full-term pregnancies last 266 days, or 38 weeks, or 9 months.
Instruction:
Click to reveal details.
Beginning of Pregnancy: Paradoxically, many obstetricians date the onset of pregnancy from the date of the woman’s last menstrual period (LMP), about 14 days before conception.
Length of pregnancy: If the LMP is used as the starting time, pregnancy lasts 40 weeks, sometimes expressed as 10 lunar months. (A lunar month is 28 days long).
Trimesters: Months 1, 2, and 3 are called the first trimester; months 4, 5, and 6, the second trimester; and months 7, 8, and 9, the third trimester.
Due Date: Babies born between three weeks before and two weeks after that date are considered “full term” or “on time.” Babies born earlier are called preterm; babies born later are called post-term. The words preterm and post-term are more accurate than premature and postmature.
Instead of germinal period, embryonic period, and fetal period, some writers divide pregnancy into three-month periods called trimesters.
Trimesters
Although doctors assign a specific due date (based on the woman’s LMP), only 5% of babies are born on that exact date.
Due date 5 5 5

6. How does implantation occur?
The First 14 Days
implantation: The process beginning about 10 days after conception, in which the developing organism nestles in, and attaches to the placenta that lines the uterus.
How does implantation occur?
The Most Dangerous Journey
Conception
Zygote (single cell)
Two-celled stage
Fallopian tube
Instruction:
After implantation, the placenta nourishes and protects the developing organism as it continues to grow and mature.
Automatic animation.
The germinal period (also called the germinal stage) is the first two weeks of prenatal development after conception, characterized by rapid cell division and the beginning of cell differentiation.
The zygote—which is the single cell formed from the union of two gametes—starts to duplicate and divide within hours of conception.
Ova
Sperm
Ovum
Implantation
Ovary 6 6 6

7. From the Third Through the Eighth Week
What happens during the embryonic period of prenatal development?
As nerves and muscles form links to the brain, the embryo now moves spontaneously, as the brain begins to move muscles.
The intestines begin to move from the umbilical cord to the embryo’s body cavity.
Brain
Intestines
Eyes and eyelids are developed. Eyes will continue to migrate to the front of the head, where they will eventually rest. Eyelids begin to grow together and are only half closed. External, middle, and inner ears are now fully formed. External ears will continue to migrate to the side of the head, where they will eventually rest.
Arms are well formed, longer, and can bend at elbows and move forward. Fingers elongate and digits are fully separated. Each finger has three digits, and the thumb has two digits.
Arms, hands and fingers
Facial Features
Urogenital membranes have developed into either male or female organs, and ovaries or testicles are visible. Clitoris or penis begins to form, but distinguishing the embryo’s sex is difficult.
External sex organs
Instruction:
Click to reveal details.
The word embryo is often used loosely, but it is just one of three periods, or stages, for a developing human prior to birth.
The embryonic period (also called the embryonic stage) is the stage of prenatal development from approximately the third through the eighth week after conception, during which the basic forms of all body structures, including internal organs, develop. This critical since it is a time when all the support systems form, along with the basic organs of the body, including the brain.
Brain
Facial Features
The head is still disproportionately large but is erect and appears rounded. The neck is well defined. The tail will disappear by the end of this week. Cartilage begins to turn into bone. The ectoderm layer is replaced by the beginnings of skin. The body becomes evenly rounded, due to the growth in the abdomen.
Arms, hands and fingers
Intestines
Overall appearance
External sex organs
Overall appearance 7 7 7

8. [Video: Germinal and Embryonic Periods]
From the Third Through the Eighth Week
Instructions: Click to start animation.
By day 56 (the end of week 8), the embryo weighs just one-thirtieth of an ounce (that’s 1 gram) and is about 1 inch (or 2 ½ centimeters) long.
[Video: Germinal and Embryonic Periods] 8 8 8

9. What happens during the fetal period of prenatal development?
From the Ninth Week until Birth
What happens during the fetal period of prenatal development?
9 weeks through 38 weeks
Instruction:
Automatic Animation.
The fetal period (also called the fetal stage) is the stage of prenatal development from the ninth week after conception until birth, during which the fetus gains about 7 pounds (more than 3,000 grams) and organs become more mature, gradually able to function on their own.
By the end of the third month, the sex organs are visible via ultrasound (also called a sonogram).
By 11 weeks, the rough brain structure is complete, and all the organ systems are present.
At about 22 weeks after conception, the fetus may survive outside of the mother’s uterus if specialized medical care is available. This is known as the “age of viability.” 9 12 16 20 24 28 32 36 38
fetus: A developing human organism from the start of the ninth week after conception until birth. 9 9 9

10. Prenatal Brain Development
Brain stem
Hindbrain
Neural tube
(forms spinal cord)
Forebrain
(a) 25 days
Midbrain
Prenatal Growth of the Brain
How does the brain grow during the periods, or stages, of prenatal development?
(b) 50 days
(c) 100 days
Instruction:
Click to reveal brain growth for that period.
By day 100, the brain looks distinctly human. By week 28, brain activity begins, and the various sections of the brain are recognizable.
When the fetus is full term, all the parts of the brain, including the cortex (the outer layers) are formed, folding over one another and becoming more convoluted, or wrinkled, as the number of brain cells increases.
(d) 20 weeks
(e) 28 weeks
(f) 36 weeks (full term) 10 10 10

11. [Video: Brain Development Animation: Prenatal]
From the Ninth Week until Birth
Instruction:
Click to show a video about prenatal brain development.
This video clip shows an animation of prenatal brain development from conception through birth.
What aspect of prenatal brain development did you find most interesting or surprising? Why?
[Video: Brain Development Animation: Prenatal] 11 11 11

12. What percentage of zygotes make it through each prenatal period?
Making it to Birth
What percentage of zygotes make it through each prenatal period?
The Germinal Period
At least 60 percent of all developing organisms fail to grow or implant properly and thus do not survive the germinal period. Most of these organisms are grossly abnormal.
The Embryonic Period
About 20 percent of all embryos are aborted spontaneously*, most often because of chromosomal abnormalities.
The Fetal Period
Instruction:
Click to reveal details.
During the germinal period, about 60 percent of natural conceptions and 70 percent of in vitro conceptions do not implant.
The embryonic period is critical for many teratogens, which are agents that can result in birth defects or even death.
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.
*Spontaneous abortions are also called miscarriages. This table does not include induced abortions.
Sources: Bentley & Mascie-Taylor, 2000; K.L. Moore & Persaud, 2003. 12 12 12

13. What are the risks at different stages of development?
Birth Defects from Teratogens: Time of Exposure and Effect on Major Organs
Germinal Period
Main Embryonic Period (in weeks)
Fetal Period (in weeks) 1 2 3 4 5 6 7 8 9 16 32 38
Common site(s)
of action of
teratogens
Highly critical
period
Less critical
period
Central nervous system
Neural-tube defects
Mental retardation
Learning disabilities
Heart
Arms
Legs
Instructions:
Automatic animation.
Since timing of exposure is a crucial factor, preconception health is at least as important as health during pregnancy. For example, one study found that, although smoking cigarettes throughout pregnancy can be lethal for the fetus, smokers who quit in the first weeks of pregnancy had no higher risks of birth complications than did women who never smoked (McCowan et al., 2009).
A situation, called threshold effect, is one in which a certain teratogen is relatively harmless in small dose, but becomes harmful once exposure reaches a certain level (the threshold). For instance, alcohol, tobacco, and marijuana do more harm in combination, thus lowering the threshold for each on its own.
Genes are another factor. When a woman carrying dizygotic twins drinks alcohol, for example, the twins’ blood alcohol levels are equal, yet one twin may be more severely affected than the other—possibly because one twin has an allele that affects the enzyme that metabolizes alcohol.
Before pregnancy women should stop smoking, avoid drugs (especially alcohol), eat a balanced diet, take supplements helpful during pregnancy, and update immunizations.
Scientists sometimes apply research in contradictory ways. For instance, U.S. pregnant women are advised not to eat much fish (in part, due to a concern about the teratogenic substance of mercury found in some fish), but pregnant women in the United Kingdom have been advised that fish consumption is beneficial to the fetus.
Lips
Cleft lip
Ears
Low-set malformed ears and deafness
Eyes
Cataract, glaucoma
Teeth
Enamel staining
Palate
Cleft palate
Sex organs
Masculinization of
female genitalia
Teratogens often
prevent implantation
Major congenital anomalies
Functional defects and minor anomalies 13
Source: Adapted from K.L. Moore & Persaud. 2003 13 13

14. What are some prenatal tests?
Benefits of Prenatal Care
What are some prenatal tests?
Instruction:
Automatic animation.
Some tests are noninvasive (like those shown here), but other tests that detect chromosomal abnormalities or other serious problems are invasive, posing greater risk. 14 14 14

15. Benefits of Prenatal Care
Instruction:
Click to show prenatal sonograms.
The sonograms you will see show a developing fetus from ages 2.5 to 6 months.
What body parts and/or organs do you see in the sonograms?
[Video: Sonogram] 15 15

16. How do you feel about viewing the birth process?
1. A close friend or relative asks you to be present during the labor and at the birth of her child You feel like saying:
Yes, I want to be there!
Yes, if you need me.
Maybe; let me think about it.
It’s something I don’t think I can do.
Don’t know; it’s hard to imagine.
2. You learn that someone took a photograph of the moment of your birth. Are you:
Very eager to see the photograph?
Interested in seeing the photograph at some time?
Turned off by the thought of the photograph?
Both interested and turned off by the idea of the photograph?
Don’t know.
Instruction
Click to reveal the answer choices to each question .
Please note, this page is available to use with a clicker system.
In the past, prospective first-time parents often approached birth with a host of fears and negative feelings.
Today, women and men are increasingly well-informed and highly positive about the birth of their babies.
It is not unusual to experience first-person accounts celebrating the birth experience.
Click to see a video that shows a birth.
In this video, you’ll witness the birth of baby Jaclyn.
3. You learn that your class is scheduled to see a film of a birth. Are you:
Very interested in seeing the film?
Somewhat interested in seeing the film?
Somewhat uneasy about seeing the film?
Very uneasy about seeing the film?
Both interested and uneasy? 16 16 16

17. [Video: Birth] Instruction: Click to play video
In what way (if at all) does watching this birth change your answers to any of the questions that were presented on the last slide?
[Video: Birth] 17 17

18. First Minutes and Complications
apgar scale: A quick assessment of a newborn’s health, given twice (at one minute and five minutes after birth).
How is a
Newborn tested?
Instruction:
In an Apgar scale assessment, the baby’s color, heart rate, reflexes, muscle tone, and respiratory effort are given a score of 2; each time the total of all five scores is compared with the maximum score of 10 (rarely attained).
anoxia: A complication at birth due to lack of oxygen, and three of the five criteria on the Apgar scale monitor the potential for this condition.
cerebral palsy: A condition based on brain damage related to movement control—used to be considered a result of problem birth procedures, but it is more often related to genetic vulnerability worsened by teratogens or maternal illness. 18 18 18

19. First Minutes and Complications
Instruction:
Click to play a video that shows a newborn.
In this video clip, you’ll see an Apgar test being given to a newborn.
Why do you think that a perfect score of 10 is rarely received by a newborn?
[Video: Apgar Test] 19 19

20. Variations in Birth Weight
Low Birth Weight (LBW): A body weight at birth of less than 5 ½ pounds (2,500 grams).
Very Low Birth Weight (VLBW): A body weight at birth of less than 3 pounds, 5 ounces (1,500 grams).
Extremely Low Birth Weight (ELBW): A body weight at birth of less than 2 pounds, 3 ounces; (1,000 grams).
Why is birth weight important?
Lagging physical and cognitive development confronts babies born early (or preterm, once called premature), and a preterm baby also is probably low birth weight.
Instruction:
Automatic animation.
Low birth weight may be the result of an illness (in mother or fetus), maternal drug use or smoking, or maternal malnutrition. This is a worldwide challenge. For example, 3 percent of babies born in nations of North Europe are low birth weight, but 30 percent of babies born in nations of South Asia weigh less than 2,500 grams. Also, the United States has a distressing incidence of infant mortality, primarily because of low birth weight.
Some low birth weight babies survive and overcome early problems if they receive excellent early care in the hospital and then at home (Spittle et al., 2009).
On the other hand, very low birth weight babies are later to smile, hold a bottle, walk, and communicate. As the months go by, cognitive difficulties as well as visual and hearing impairments may emerge. And as adults, some risks persist for low birth weight babies including, ironically, higher rates of obesity, heart disease, and diabetes.
Click to see a video about low birth weight babies.
This video focuses on programs and research on low birth weight babies in India.
Click to see a video about a preterm newborn.
In this clip, you’ll see how a hospital cares for a preterm infant.
Click to see another video about a preterm newborn.
In this clip, you’ll see how a parent and preterm baby interact.
Play video:
Low Birth weight in India
Play video:
An Observation of Premature Infants Clip E
Play video:
An Observation of Premature Infants Clip F 20 20 20

21. [Video: Low Birth Weight - India]
Variations in Birth Weight
Instruction:
Click to Play video
According to this video, how does low birth weight affect development across generations in India?
[Video: Low Birth Weight - India] 21 21

22. [Video: An Observation of Premature Infants]
Variations in Birth Weight
Instruction:
Click to play video
What is done to help this preterm baby survive and thrive?
[Video: An Observation of Premature Infants] 22 22

23. [Video: An Observation of Premature Infants]
Variations in Birth
Instruction:
Click to play video
What is done to help this preterm baby bond with its mother?
[Video: An Observation of Premature Infants] 23 23

24. Variations in Birth What are some newborn reflex experiences?
Instruction:
A reflex occurs without conscious thought.
Automatic animation.
The breathing and sucking reflexes are necessary for a child’s survival.
Some reflexes aren’t necessary for survival, but they do indicate the state of brain and body functions. This animation shows the stepping reflex, which is when the baby’s legs move as if the infant is walking (and that happens whenever a baby is held upright with feet touching a flat surface). You also see the Moro reflex, when a baby flings its arms outward and then brings them together on its chest, as it cries with eyes wide open.
Breathing reflexes
Sucking reflexes
Stepping reflexes
Moro reflexes
reflex: An unlearned, involuntary action or movement in response to a stimulus. 24 24 24

25. [Video: Newborn Reflexes]
Instruction:
Click to see a video about newborn reflexes.
In this video, you’ll see several babies, each demonstrating a different reflex.
Based on the actions of the babies in the video, which reflexes are shown in the clip?
[Video: Newborn Reflexes] 25 25

26. Social Support What is a father’s role?
Instruction:
Fathers can be crucial during prenatal development and a newborn’s life.
couvade: Symptoms of pregnancy and birth experienced by fathers. 26 26 26

27. [Video: The Experience of Pregnancy: The First Trimester]
Social Support
Instruction:
Click to play a video about a father-to-be.
In this video an expectant father talks about his wife, their pregnancy, and the child they are expecting.
In what ways is the father in this video involved in his child’s birth and early infancy?
[Video: The Experience of Pregnancy: The First Trimester] 27 27

28. Closing Thoughts
From what you discovered about prenatal development in these slides, what examples can you cite to support the statement, “The most dramatic and extensive transformation of the entire life span occurs before birth?” 28 28