Transcript Chapter 4: The Period of Pregnancy and Prenatal Development

The Period of Pregnancy and
Prenatal Development
Infant Mortality
• Number of infants who die during first year of
life per 1,000 live births during that year
• 2006: U.S. rate was estimated at 6.7 deaths
per 1,000 lived births
• Two thirds of infant deaths occur during the
first month after birth
• What accounts for the fact that the United
States is behind so many other industrialized
countries in the rate of infant mortality?
Genetics and Development
• Variability is guaranteed by the complexity of
the human genome and the mechanisms for
genetic inheritance
• Human genetics establishes a foundation for
appreciating the biological basis of human
diversity
Chromosomes and Genes as Sources
of Genetic Information
• Chromosomes
– Rod-like structures in the nucleus
– Store and transmit genetic information
• There are 23 pairs of chromosomes in each
human cell
• Sex is determined by whether an X-bearing or
a Y-bearing sperm fertilizes the ovum
– XX in females, and XY in males
A Small Part of a DNA Molecule
The Principles of Heredity
• Gregor Mendel discovered the laws that
govern the process of genetic inheritance
– Series of experiments with pea plants in his
monastery garden
• Alleles: each gene has at least two states—
one on each chromosome strand in the pair
– Homozygous
– Heterozygous
The Principles of Heredity
• Genotype:
– Genetic information about a trait
• Phenotype
– Observed characteristic (e.g., eye color, hair color)
• Cumulative relation
• Codominance
• Dominance
The Principles of Heredity
The Principles of Heredity
• What is epigenetics?
• Sex-linked characteristics: genes for specific
characteristics are found on X and Y
chromosomes
• Three areas in which genetic determinants
contribute to individual variability
– The rate of development
– Individual traits
– Abnormal development
Epigenetic Mechanisms
Sex-Linked Inheritance of Hemophilia
Genetic Technology and Psychosocial
Evolution
• Genetic counseling and prenatal diagnosis
permit people to make informed decisions
about conceiving or carrying a pregnancy to
term
• Ethical considerations
– Nuclear transplantation
Case Study: Karen and Don
• Reflections
– Try to put yourself in the roles of the main
characters in this case: Karen, Don, Karen’s
mother, Don’s mother, and Don’s father. How
might you react?
– How might these experiences influence how Karen
and Don each view their marital relationship?
– What are the ethical considerations in this case?
Your Perspective
• Consider the issues faced by Karen and Don
through a cultural lens
• In what ways did their culture influence their
attitudes towards pregnancy, childbirth, and
abortion?
• In what ways would your culture influence you
under similar circumstances?
Gene X Environment Interactions
and Behavior
• Genetics and intelligence
– Specific genetic irregularities can cause
degrees of mental retardation
– The influence of genetics on intelligence can
be understood through the study of family
relationships
Gene X Environment Interactions
and Behavior
The Norm of Reaction
Normal Fetal Development
• Fertilization
– Only one sperm can fertilize an ovum
– Sperm carry genetic material necessary for
reproduction
– Gametes contain only one of each chromosome
• How do twins develop?
Infertility and Alternative Means of
Reproduction
• Infertility:
– Increases with age
– May place great stress on a couple
• What legal and ethical questions have arisen
from assistive reproductive technologies
(ARTs)?
• Would you consider adoption?
Development in the First Trimester
• The germinal period (weeks 1-2)
– After fertilization, the tiny mass of cells (zygote)
travels out of the fallopian tube and implants in
the uterine wall
Development in the First Trimester
• The embryonic period (weeks 3-8)
– Amniotic sac: forms and encloses the developing
organism in amniotic fluid
– Placenta: allows nutrients and waste to pass from
the mother to the developing child
– The groundwork for all body structures and
internal organs formed
– Sensitivity to teratogens: agents that can produce
malformations in the fetus
Development in the First Trimester
Critical Periods in Prenatal
Development
Development in Second Trimester
• Quickening (approx. 17-20 weeks)
– Developing fetus has grown large enough that its
movements can be felt by the mother
• Fetus begins to suck and swallow
• End of sixth month, sensory receptors of the
fetus are well established
Development in the Third Trimester
• Critical level of neurological maturation in
place by 32 weeks
• At the end of the third trimester:
– The fetal brain produces hormones
triggering the birth process
The Birth Process
The Birth Process
Caesarean Delivery
• Removing the baby surgically through an
incision in the uterine wall
– Increased from 5.5% of births in 1970 to 33% in
2010
• U.S. Public Health Service calls for a reduction
of the national cesarean rate
The Mother, the Fetus, and the
Psychosocial Environment
• What is the impact of the fetus on the
pregnant woman?
– Changes in roles and social status
– Changes in the mother’s emotional state
– Fathers’ involvement during pregnancy and
childbirth
Impact of the Pregnant Woman on
the Fetus
• Major factors
– Poverty
– Mother’s age
– Maternal drug use
– Nicotine
– Alcohol
– Caffeine
– Narcotics
– Prescription drugs
– Obstetric anesthetics
– Environmental toxins
– Mother’s diet
The Cultural Context of
Pregnancy and Childbirth
• Reactions to pregnancy
– Solicitude versus shame:
• Care, interest, and help of others versus shame,
condemnation, and secrecy
– Adequacy versus vulnerability:
• Sign of sexual prowess and entrance into social status
versus tiring, exhaustion, and lots of work
The Cultural Context of
Pregnancy and Childbirth
• Reactions to childbirth
– Every society marks the importance of childbirth
in different ways
– Americans focus on:
• Safety of the mother and child
• Building a sense of competence in the mother and the
father as they approach the care of their newborn
Applied Topic: Abortion
• Termination of a pregnancy before the fetus is
able to live outside the uterus
– Miscarriage
• Legal and political context of abortion in U.S.
– Developmental viability
– Fetal viability
– Roe v. Wade
Applied Topic: Abortion
• The abortion ratio in the U.S. for 2007 was
19.4 abortions per 1000 women
• What are the characteristics of women who
have abortions?
– Diverse socioeconomic, developmental, and family
contexts
• What is the psychosocial impact of abortion?
– Consider men’s reactions to abortion as well
Legal Abortions in the United States
Surrogacy & Classism
• 1.If you were considering hiring a surrogate, how important would her
race, education, skin color and class be if she has no genetic relationship
to the child for whom you are the intended parent?
• 2 Should the purchase price of genetic material be regulated by the
federal government? Do you think there should be limits on how much
sperm or how many eggs can be donated by one individual?
• 3 How does the sale and consumption of genetic material differ from
other forms of consumption? What ethical concerns do you have about
this industry?
• 4 Do you think that children conceived with donated sperm that has been
purchased have the right to know the identity of their genetic father when
they reach 18? Why or why not?
• 5 Other comments on this issue?