CHAPTER 3
PRENATAL DEVELOPMENT AND BIRTH
RESOURCES-AT-A-GLANCE
Detailed Outline
Learning
Objectives
Instructor’s Resources
Test Bank
MyPsychLab Connection
Chapter Introduction pp. 48–49
PowerPoint Slides
1-4
Sketchnote Videos
Genetics and Prenatal
Development
Birth and the Newborn
5-16
Genetic and Chromosomal
Disorders pp. 54-57
Genetic Disorders
Chromosomal Errors
3.3
3.4
PowerPoint Slides
17–23
MC 24-36
FI 79–80
SA 96
ES 109
PowerPoint Slides
Pregnancy and Prenatal
Development pp. 57–64
PowerPoint Slides
24–34
MC 37-57
FI 81–84
Watch
Period of the Zygote, p. 57
CHAPTER OVERVIEW
Human development begins with the genes and chromosomes passed on to the new individual at the
moment of conception and is impacted by the prenatal environment. From conception to birth, prenatal
development follows a truly amazing course that begins with a single cell and ends with a crying, but
curious, newborn making his or her debut in the outside world.
Many disorders appear to be transmitted through the operation of dominant and recessive genes.
Autosomal disorders are caused by genes located on the autosomes; the genes that cause sex-linked
disorders are found on the X chromosome. A variety of problems can be caused when a child has too
many or too few chromosomes, a condition referred to as chromosomal error or chromosomal anomaly.
Pregnancy is a physical condition in which a woman’s body is nurturing a developing embryo or fetus.
Prenatal development, or gestation, is the process that transforms a zygote into a newborn. Pregnancy is
usually divided into trimesters, three periods of 3 months each. The three stages of prenatal development
amniocentesis, are used to identify problems prenatally.
Once gestation is complete, the fetus must be born into the world. In industrialized countries, especially
in the United States, parents have several choices, including birth attendants, whether or not to use drugs
during delivery, and the location of the birth. Labor is typically divided into three stages. Stage 1 covers
LEARNING OBJECTIVES
After completing Chapter 3, students should be able to answer the following learning objective questions:
3.1 What are the characteristics of the zygote?
3.2 In what ways do genes influence development?
3.3 What are the effects of the major dominant, recessive, and sex-linked diseases?
3.4 How do trisomies and other disorders of the autosomes and sex chromosomes affect
development?
3.5 What are the characteristics of each trimester of pregnancy?
3.6 What happens in each stage of prenatal development?
KEY TERMS
amnion (p. 59)
gonads (p. 50)
anoxia (p. 75)
implantation (p. 59)
axons (p. 62)
low birth weight (LBW) (p. 76)
cell body (p. 61)
multi-factorial inheritance (p. 53)
cephalocaudal pattern (p. 59)
neonate (p. 75)
cesarean section (c-section) (p. 73)
neurons (p. 59)
chromosomes (p. 49)
organogenesis (p. 61)
dendrites (p. 62)
phenotype (p. 51)
deoxyribonucleic acid (DNA) (p. 49)
placenta (p. 59)
dominant-recessive pattern (p. 51)
polygenic inheritance (p. 53)
embryonic stage (p. 59)
proximodistal pattern (p. 59)
fetal stage (p. 61)
synapses (p. 62)
gametes (p. 49)
teratogens (p. 64)
genes (p. 49)
umbilical cord (p. 59)
genotype (p. 51)
viability (p. 61)
germinal stage (p. 59)
zygote (p. 49)
glial cells (p. 62)
INTEGRATED CHAPTER TEACHING NOTES
CONCEPTION AND GENETICS (pp. 49-54)
MyPsychLab Connections
The Process of Conception
LO 3.1 What are the characteristics of the zygote?
Conception occurs when a sperm penetrates an ovum, typically in a woman’s fallopian tube. If the ovum
Discussion Launcher (Learning Objective 3.1, p. 49)
Research indicates that only about half of all conceptions are likely to survive to birth. What are some
reasons for this large number of fertilized eggs not surviving?
Chromosomes, DNA, and Genes
Most cells in the human body contain 23 pairs of chromosomes. Gametes are sperm and ovum cells that
have only 23 unpaired chromosomes. Chromosomes are composed of molecules of a chemical called
Discussion Launcher (Learning Objective 3.1, p. 49)
What would happen if gametes had more (or less) than 23 chromosomes?
Determination of Sex
There are two types of chromosomes: autosomes and sex chromosomes. Twenty-two of the pairs of
chromosomes are called autosomes. They look alike and contain matching genetic pairs. The sex
chromosomes are called either X or Y. A human female has two X chromosomes (XX) and a male has
Discussion Launcher (Learning Objective 3.1, pp. 49-50)
What might be some psychological results of a person who is male but lacks male genitals? What about a
female who has male genitals?
Development of the gonads, testes in males and ovaries in females, also depend on the presence or
Multiple Births
Fraternal twins, also called dizygotic twins, are conceived when two eggs are fertilized by two separate
sperm. Identical twins, also called monozygotic twins, are conceived when a single fertilized ovum
Discussion Launcher (Learning Objective 3.1, pp. 50-51)
Can you think of other reasons for the increase in multiple births?
Feature Box Activity (Learning Objective 3.1, p. 51)
Research Report: Twins in Genetic Research
The text gives evidence that psychological traits are not determined by the genes in the same way as
physical traits, such as blood type. How do you explain the difference?
How Genes Influence Development
LO 3.2 In what ways do genes influence development?
Dominant and Recessive Genes
The simplest set of genetic rules is the dominant-recessive pattern in which a single dominant gene
strongly influences phenotype. Because we inherit one chromosome from each parent, our genetic
instructions may be either homozygous (the same) or heterozygous (different). You are homozygous for
Discussion Launcher (Learning Objective 3.2, pp. 51-52)
Think about your hair type and that of your siblings. What does your hair suggest about your parents’
genotypes?
Both dominant and recessive genes differ in expressivity, meaning that the degree to which any gene
influences phenotypes varies from person to person. In other words, all individuals with curly hair don’t
have equally curly hair.
Polygenic Inheritance
With polygenetic inheritance, many genes influence the phenotype. The interaction of several genes,
Discussion Launcher (Learning Objective 3.2, p. 53)
What might be some factors that cause a child to be considerably shorter than her agemates?
Other Types of Inheritance
A genetic imprint is a chemical marker that identifies each gene in a person’s body as having come from
his father or mother. Genomic imprint has implications for development because they possibly “turn on”
an atypical development process or “turn off” a normal one. Imprints may cause responses in other genes
Discussion Launcher (Learning Objective 3.2, p. 53)
How do you suppose the research was conducted that discovered mitochondrial inheritance?
Multi-Factorial Inheritance
There are many physical traits that are influenced by both genes and environment, a pattern known as
multi-factorial inheritance. Height is one example. If a child is ill, poorly nourished, or emotionally
Critical Thinking Question (Learning Objectives 3.1-3.2, pp. 49-54)
In what ways have genetic and environmental influences interacted to influence your development?
GENETIC AND CHROMOSOMAL DISORDERS (pp. 54-57)
Genetic Disorders
LO 3.3 What are the effects of the major dominant, recessive, and sex-linked diseases?
Many disorders appear to be transmitted through the operation of dominant and recessive genes.
Discussion Launcher (Learning Objective 3.3, p. 54)
Why do you suppose sex-linked disorders are found on the X chromosome rather than the Y
chromosome?
Autosomal Disorders
Most recessive disorders are diagnosed in infancy or early childhood. The following are examples of
autosomal disorders:
▪ Phenylketonuria (PKU) involves a recessive gene that causes a baby to have problems digesting the
amino acid phenylalanine. It can cause developmental retardation as the toxins build up in the baby’s
brain. It is more likely to occur in Caucasian babies than infants in other ethnic groups.
Discussion Launcher (Learning Objective 3.3, pp. 54-55)
Why don’t all of us display these recessive disorders? What factors would increase your chances of
having a child that displayed these recessive-gene diseases?
Sex-Linked Disorders
Most sex-linked disorders are caused by recessive genes. The following are examples of common sex-
linked disorders:
Discussion Launcher (Learning Objective 3.3, p. 55)
The text states that when potential parents know they carry a gene that can cause prenatal damage, they
Chromosomal Errors
LO 3.4 How do trisomies and other disorders of the autosomes and sex chromosomes affect
development?
A variety of problems can be caused when a child has too many or too few chromosomes, a condition
referred to as a chromosomal error or chromosomal anomaly. Like genetic disorders, they are
distinguished by the involvement of either autosomes or sex chromosomes.
Trisomies
A trisomy is a condition in which a child has three copies of a specific autosome. The most common is
Sex-Chromosome Anomalies
The following are examples of anomalies associated with the sex chromosomes:
▪ Klinefelter’s syndrome is associated with an XXY pattern. Affected boys usually look normal but
Discussion Launcher (Learning Objective 3.4, pp. 56-57)
Mental retardation is listed as a symptom of many of the genetic disorders. Why do you suppose that is?
Critical-Thinking Question (Learning Objectives 3.3-3.4, pp. 54-57)
In your view, what are the advantages and disadvantages of genetic counseling for couples who want to
have a child, but who are concerned about genetic or chromosomal disorders that run in one or both of
their families?
PREGNANCY AND PRENATAL DEVELOPMENT (pp. 57-64)
MyPsychLab Connections
Watch: Period of the Zygote, p. 57
Watch: Prenatal Development: Pregnancy and Prenatal Care, p. 57
Watch: Fetal Development, p. 61
The Mother’s Experience
LO 3.5 What are the characteristics of each trimester of pregnancy?
First Trimester
Pregnancy begins when the zygote implants itself in the lining of the woman’s uterus. The zygote then
sends out chemical messages that cause the woman’s menstrual periods to stop. Some of these chemicals
are secreted in her urine, making it possible to confirm pregnancy within a few days after conception.
Discussion Launcher (Learning Objective 3.5, pp. 57-58)
Why can’t a woman depend on symptoms, such as morning sickness, to accurately confirm her
pregnancy?
Prenatal care is essential in the first trimester to prevent birth defects because all of the baby’s organs
form during the first 8 weeks. Early prenatal care can identify maternal conditions, like sexually
transmitted diseases that may threaten prenatal development. Medical personnel can also urge women to
abstain from drugs and alcohol during pregnancy.
Second Trimester
During the second trimester, morning sickness usually disappears, resulting in an increase in appetite.
The woman gains weight and the uterus expands to accommodate the rapidly growing fetus. The woman
begins to feel the fetus’s movements between the 16th and 18th weeks of pregnancy.
Prenatal visits include monitoring the mother’s and the baby’s vital functions and keeping track of the
Discussion Launcher (Learning Objective 3.5, p. 58)
Would you want to know the sex of the baby before delivery? Why or why not?
The risk of miscarriage drops in the second trimester; however, a few fetuses die between the 13th and the
20th weeks of pregnancy. Premature labor after the 21st week can result in delivery of a living, but
extremely small, baby.
Discussion Launcher (Learning Objective 3.5, p. 58)
If we use the premise that healthy babies are “cheaper” than unhealthy babies, what economic aspects
would make this statement true? List as many as possible. Are the expenses of an unhealthy baby borne
only by the parents? Explain your answer.
Third Trimester
At 25 weeks, the pregnant woman enters her third trimester. Weight gain and abdominal enlargement are
the main experiences of this period. The woman’s breasts may secrete a substance called colostrum in
preparation for nursing.
Prenatal Development
LO 3.6 What happens in each stage of prenatal development?
In contrast to the three trimesters of pregnancy, the three stages of prenatal development are defined by
Discussion Launcher (Learning Objective 3.6, p. 59)
Why is it logical that development follows these two principles?
The Germinal Stage
The first 2 weeks of gestation, from conception to implantation, constitute the germinal stage. During the
first 24 to 36 hours after conception, cell division begins. The cells are all alike until about four days after
conception; they form a hollow sphere with two layers and are called a blastocyst. The outer cells form
Discussion Launcher (Learning Objective 3.6, p. 59)
Why do you think that the mother’s and the baby’s blood are close to one another but not mixed? What
would happen if the mother’s and the baby’s blood mixed?
The blastocyst’s inner cells begin to specialize. One group of cells will become the umbilical cord, the
The Embryonic Stage
The embryonic stage begins when implantation is complete, at about the end of the 2nd week of
pregnancy. It continues for 6 weeks, until the end of week 8. The embryo’s cells start to specialize to
form the foundations of all the body’s organs.
▪ In the 3rd week after conception, the cells of the nervous system, neurons, form a structure called the
neural tube from which the brain and spinal cord will develop. A primitive heart and the forerunner
▪ During week 7, embryos begin to move spontaneously. They have visible skeletons and fully
Discussion Launcher (Learning Objective 3.6, pp. 59-61)
The embryonic period is often called the “critical period of prenatal development.” Why?
The Fetal Stage
The final stage is the fetal stage, beginning at the end of week 8 and continuing until birth, about 7
months. The fetus’s weight grows from one-fourth ounce to seven or eight pounds, and its length
Discussion Launcher (Learning Objective 3.6, p. 61)
Why is it important for babies to reach full term (38 weeks)? Hint: What does this information tell you
about pre-term babies and low-birth-weight babies?
Discussion Launcher (Learning Objective 3.6, p. 61)
In the context of all the debate about abortion, why is it relevant to establish the average age of viability?
The Fetal Brain
The foundational structures of all of the body’s organ systems are formed during the embryonic stage.
Yet most of the formation and fine-tuning of the brain takes place during the fetal stage. Neurons are
Discussion Launcher (Learning Objective 3.6, pp. 61-62)
Why do you think neurons consist only of cell bodies while migrating?
Sex Differences
LO 3.7 How do male and female fetuses differ?
Because prenatal development is strongly influenced by maturational codes that are the same for both
males and females, there are only a few sex differences in prenatal development. The following is a list
of some of them:
▪ Female fetuses appear to be more sensitive to external stimulation and advance more rapidly in
skeletal development.
Discussion Launcher (Learning Objective 3.7, pp. 61-62)
Why do you think boys are more vulnerable to prenatal difficulties than girls?
Prenatal Behavior
LO 3.8 What behaviors have scientists observed in fetuses?
Following are some of the behaviors that have been displayed by fetuses:
▪ By the 32nd or 33rd week, fetuses can distinguish between familiar and novel stimuli.
Discussion Launcher (Learning Objective 3.8, pp. 63-64)
Critical Thinking Question (Learning Objectives 3.5-3.8, pp. 57-64)
Why do you think most expectant mothers become emotionally attached to their unborn children during
the third trimester?