Human Reproduction (II) – JSS1 Basic Science Lesson Note (Third Term)

Pregnancy is the period between fertilisation and the birth of the young one, and in humans it lasts about nine months.

Behavioural objectives

1. Define pregnancy.
2. State the signs and symptoms of pregnancy.
3. List the care a woman needs during pregnancy.
4. Tell the difference between myths and facts about pregnancy.
5. Describe the growth of the fetus month by month.

What is pregnancy?

Pregnancy is the period between fertilisation and the birth of the young one.

• Length: about nine (9) months in humans.
• Fertilisation: the joining of a sperm cell and an egg to form a zygote.
• Conception: another name for fertilisation, the moment the baby’s life begins.
• Result: the fertilised egg grows into an embryo and then a fetus.

What are the signs and symptoms of pregnancy?

The signs of pregnancy are body changes that tell a woman she may be pregnant, mostly caused by changes in hormones.

1. Food aversions: a newly pregnant woman may dislike the smell of some foods or no longer enjoy foods she liked before.
2. Mood swings: hormonal changes make a pregnant woman’s mood change often.
3. Abnormal bloating: hormonal changes may cause bloating similar to the feeling before a period.
4. Frequent urination: more blood flows through the kidneys, so the bladder fills faster.
5. Fatigue: she feels tired and sleepy because of changes in metabolism and hormones.
6. Sore breasts: the breasts become swollen and sensitive as hormone levels rise.
7. Missed period: a missed period is a common sign, although some women still have light bleeding.
8. High basal body temperature: body temperature that stays raised for 18 consecutive days may point to pregnancy.

What care is needed during pregnancy?

A pregnant woman needs medical care, good food, rest and a healthy way of life to protect herself and the baby.

1. Take a pregnancy test as soon as you miss your period.
2. Talk with your partner and someone you trust.
3. Begin antenatal care check-ups with a medical doctor.
4. Follow the antenatal instructions and avoid drugs that are not prescribed.
5. Eat nourishing foods rich in protein, calcium, folic acid, iodine and iron.
6. Drink plenty of water and fruit juices.
7. Get enough rest.
8. Avoid smoking and alcohol.

What are the myths and facts about pregnancy?

A myth is a false belief that many people hold, while a fact is a truth that can be proven.

• Myth: a belief passed from person to person with no scientific proof.
• Fact: a statement supported by evidence and medical advice.
• Note: many African societies hold myths about pregnancy that are not scientifically true.

What are the common myths about pregnancy?

What are the facts about pregnancy?

• Heavy objects: a pregnant woman should not carry heavy objects, because they can strain her body.
• Light bleeding: some women have light bleeding and are still pregnant.
• Cat litter: a pregnant woman should not change cat litter, because it can carry germs that harm the baby.
• Alcohol: a pregnant woman should not drink alcohol, because it can harm the baby.
• Length: some pregnancies last longer than nine months.

What are the stages of growth of the fetus?

The fetus grows through the zygote, embryo and fetus stages inside the uterus over three trimesters.

1. Each month a group of eggs (oocytes) develops in the ovary.
2. Usually one egg matures and is released during ovulation.
3. After fertilisation, the zygote begins to divide and travels down the fallopian tube.
4. The zygote reaches the uterus and attaches to its wall (implantation).
5. After implantation it develops into an embryo.
6. After the 8th week the embryo is called a fetus.

What are the three trimesters of pregnancy?

A trimester is a period of three months, and pregnancy has three of them.

Month-by-month fetal development

Month 1

• The amniotic sac forms around the embryo.
• The placenta develops to supply nutrients.
• The heart begins to beat.
• Length: about ¼ inch (smaller than a grain of rice).

Month 2

• Facial features and limbs start forming.
• The neural tube (brain and spinal cord) develops.
• The baby is about 1 inch long.
• The heartbeat can usually be detected.
• The embryo becomes a fetus by the end of the month.

Month 3

• Arms, hands, fingers, feet and toes are fully formed.
• Teeth and nails begin to develop.
• Organs become functional.
• Length: about 4 inches. Weight: about 1 ounce.

Month 4

• The heartbeat can be heard with a Doppler device.
• Hair, eyelashes, eyebrows and nails form.
• The nervous system begins to function.
• The sex of the baby can be seen on ultrasound.
• Length: about 6 inches. Weight: about 4 ounces.

Month 5

• The baby starts moving (quickening).
• Hair begins to grow.
• The skin is covered with vernix caseosa, a waxy protective coating.
• Length: about 10 inches. Weight: ½ to 1 pound.

Month 6

• The skin is reddish and wrinkled, and veins are visible.
• The eyelids open and the baby responds to sounds.
• The baby may survive with intensive care if born early.
• Length: about 12 inches. Weight: about 2 pounds.

Month 7

• The baby gains body fat.
• Hearing is fully developed.
• The baby moves often and responds to stimuli.
• Length: about 14 inches. Weight: 2 to 4 pounds.

Month 8

• Brain development continues rapidly.
• The baby can see and hear.
• The lungs are still maturing.
• Length: about 18 inches. Weight: about 5 pounds.

Month 9

• The lungs are nearly fully developed.
• The baby’s reflexes are well coordinated.
• The baby moves into the birth position (head down).
• Length: 18 to 20 inches. Weight: about 7 pounds.

Evaluation

1. What is pregnancy?
2. State four (4) signs of pregnancy.
3. Give four (4) facts about pregnancy.
4. Name the three trimesters of pregnancy and the months in each.

Assignment

In your notebook, answer all three parts.

1. List five signs and symptoms of pregnancy.
2. State four ways a pregnant woman can take care of her health.
3. Describe how the baby develops in Month 5 of pregnancy.