1. Module 4

1.9. Page 2

Lesson 2

Module 4—From Fertilization to Birth

Explore

 

fetal alcohol spectrum disorder: a permanent syndrome of birth defects caused by maternal intake of alcohol during pregnancy; includes disorders of growth, behaviour, and cognitive abilities

 

lactation: the production and secretion of milk from the breast; also known as “nursing”

 

parturition: childbirth or labour

To understand fetal development, complete the Read and Watch and Listen activities. You may choose the order in which you complete the activities. As you work through the material, record the information in your course folder. Include the concepts of teratogens, fetal alcohol spectrum disorder, parturition, and lactation in your work. Consider the significance of “Figure 15.12” on page 522 of the textbook.

 

Read

 

Understanding the events of embryonic and fetal development and how substances and other factors can help or be harmful to prenatal development will be better understood after you read from the start of page 520 up to the heading “Parturition: Delivery of the Baby” on page 523 in your textbook. Also, take the time to do an Internet search using the search words “fetal development” for more information.

 

Watch and Listen

 

Watch the following videos to gain a better understanding of the events of fetal development.

  • The “Fetal Development and Birth: An Amazing Transformation” video outlines the development of fetal systems during each trimester and identifies the hormones and genetic factors involved in regulating fetal development. It also illustrates the mechanism for exchanging nutrients and wastes between the mother and fetus, and describes environmental influences, such as alcohol and drugs.

    You may be required to enter a username and password to access the video. Contact your teacher for this information.

For an illustrated presentation of the pregnancy timeline, do a web search using the search terms “pregnancy timeline” “and “aboutkidshealth.” Click on “Pregnancy and Babies: Fetal Development.”

  • This video reviews the pregnancy timeline from fertilization and implantation through to full-term fetal development.
Try This

 

TR 1. Ensuring proper nutrition is just as important as staying away from harmful teratogens when pregnant. Read “Thought Lab 15.1: Folic Acid and Neural Tube Defects” on page 524 of your textbook. Answer the “Analysis” questions and then check your answers with your teacher to see how well you understand the importance of the need for folic acid.

 

TR 2. See how well you know the major events of prenatal development by completing this drag-and-drop activity.

 

Discuss

 

Discuss one, some, or all of the following questions in the discussion area for your class.

 

D 1. Why are most women who wish to become pregnant told by their doctor to take a prenatal vitamin supplement?

 

D 2. There are many teenage pregnancies every year in Canada. Do you see a possible problem with some teenage dietary habits and teenage pregnancy?

 

D 3. Can you think of any everyday household substances that pregnant mothers should stay away from?

 

D 4. Why should pregnant women not change cat litter boxes?

 

Self-Check

 

SC 1. See how well you understand fetal development by answering questions 24 to 26 on page 520 and questions 27 and 28 on page 523 of your textbook. Discuss your answers with your teacher.

 

Check your work.
Self-Check Answers

 

Textbook questions 24 to 26, page 520

  1. The main difference between the embryonic and fetal development periods relate to the type of development of the organism. The embryonic period is a time of morphogenesis when the organs are formed. During the fetal period the organs continue to develop.

  2. You can list any three of the following events during the second trimester:

    • heartbeat can be heard with a stethoscope

    • the bones of the skeleton and joints begin to form

    • face begins to look distinctly human

    • the brain grows rapidly

    • the nervous system begins to function

    • the mother can feel fetal movements as the limbs grow and develop

    • fetus becomes covered with fine soft hair and an oily substance

    • skin becomes more pink as capillaries extend into it

    • body becomes larger in relation to the head

    • the scalp develops hair

    • eyes open

    • eyelashes form

    • fetus assumes “fetal position”

  3. Students can list any three of the following events during the third trimester:

    • brain cells form rapidly

    • testes descend in males

    • fat develops beneath the skin

    • fetus shifts to head-first position

    • bone marrow takes over production of red blood cells

    • the digestive and respiratory systems mature

    • lanugo is shed

Textbook questions 27 and 28, page 523

  1. Teratogens are agents that cause structural abnormalities due to exposure during pregnancy.

  2. Examples of dangers that teratogens pose include:

    • structural abnormalities, such as deformed limbs (prescription medication, e.g., Thalidomide)

    • constriction of blood vessels, restricting oxygen supply and increasing risk of underweight babies, premature birth, stillbirth, and miscarriage (cigarette smoke)

    • damage to the brain, central nervous system, and physical development, leading to decreased weight, height, head size, capacity to learn, memory problems, and personality disorders (alcohol)

    • excess amounts of vitamin C consumed by the mother can result in the baby being prone to scurvy, easy bruising, and infections

    • increased danger of miscarriage, low birth-weight babies, difficulty fighting infection and disease, developmental delay (exposure to environmental contaminants)

Inquiry into Biology (Whitby, ON: McGraw-Hill Ryerson, 2007), TRG Pg 6-47. Reproduced by permission