Pregnancy

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Fertilisation and Implantation

Pregnancy begins when a **sperm** fertilises an **egg**, usually in the **fallopian tube**.
The fertilised egg is called a **zygote**.
The zygote travels down the fallopian tube to the **uterus**.
The zygote **implants** into the thickened lining of the uterus.

First Trimester (Weeks 1–12)

The developing baby is called an **embryo** in early weeks.
The heart, brain, and other organs begin to form.
By the end of this trimester, the baby is called a **foetus** and is about the size of a lemon.

Second Trimester (Weeks 13–26)

The baby grows, developing muscles, bones, fingers, toes, and facial expressions.
The baby can move, and the mother may feel these movements.
The baby begins to hear sounds.

Third Trimester (Weeks 27–40)

The baby grows rapidly and gains weight.
The **lungs** mature.
The baby moves into a **head-down position**, ready for birth.
By the end, the baby is fully developed.

Supporting Structures

The **placenta** provides nutrients and oxygen from the mother's blood and removes waste.
The **umbilical cord** connects the baby to the placenta.
The **uterus** stretches and grows as the baby gets bigger.
The **amniotic sac** surrounds the baby, filled with **amniotic fluid** that cushions and protects.
The **cervix** remains closed during pregnancy and opens (dilates) for birth.
The **vagina** is the passage through which the baby is born.

Diagram showing the foetus in the uterus with placenta, umbilical cord, amniotic fluid, cervix, and vagina.

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Practice questions

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1.What is a fertilised egg called?
Easy
- AZygote
- BEmbryo
- CFoetus
- DGamete
2.Where does fertilisation usually occur?
Easy
- AFallopian tube
- BUterus
- CVagina
- DCervix
3.What is the approximate length of a full-term pregnancy?
Easy
- A40 weeks
- B30 weeks
- C50 weeks
- D20 weeks
4.Which of the following is the correct order of development?
Medium
- AZygote → embryo → foetus
- BEmbryo → zygote → foetus
- CFoetus → embryo → zygote
- DZygote → foetus → embryo
5.What is the main function of the placenta?
Medium
- ATo provide nutrients and oxygen to the baby and remove waste
- BTo produce amniotic fluid
- CTo push the baby out during birth
- DTo connect the uterus to the vagina
6.Which structure surrounds and cushions the baby with fluid?
Medium
- AAmniotic sac
- BUmbilical cord
- CPlacenta
- DUterus
7.During which trimester do the baby's lungs mature?
Medium
- AThird trimester
- BFirst trimester
- CSecond trimester
- DNone of the above
8.What happens to the cervix as birth approaches?
Hard
- AIt gradually opens
- BIt closes tightly
- CIt contracts rhythmically
- DIt produces more amniotic fluid

More questions

9.Which of the following is NOT a function of the amniotic fluid?
Hard
- AProviding nutrients to the baby
- BCushioning the baby
- CAllowing the baby to move
- DProtecting the baby
10.What is the role of the umbilical cord?
Hard
- AIt connects the baby to the placenta
- BIt produces amniotic fluid
- CIt holds the baby in the uterus
- DIt pushes the baby out during birth
11.After implantation, the developing baby is first called an embryo. At what stage does it become a foetus?
Hard
- AAfter the first trimester (around 12 weeks)
- BAfter fertilisation
- CAfter the second trimester
- DJust before birth
12.Which structure remains closed during pregnancy to keep the baby inside?
Hard
- ACervix
- BVagina
- CFallopian tube
- DUmbilical cord
13.The table below shows the average mass of a foetus at different weeks of pregnancy. At which week does the foetus gain the most mass? Week 20: 0.3 kg Week 25: 0.7 kg Week 30: 1.2 kg Week 35: 2.4 kg Week 40: 3.4 kg
Medium
- ABetween weeks 20 and 25
- BBetween weeks 25 and 30
- CBetween weeks 30 and 35
- DBetween weeks 35 and 40
14.During a pregnancy scan, the diameter of the foetal head is measured and plotted on a growth chart. If the head diameter is below the 10th percentile, what might this indicate?
Medium
- AThe baby is growing faster than normal
- BThe baby may be smaller than expected for its gestational age
- CThe baby is definitely going to be born early
- DThe mother has a multiple pregnancy
15.A study measured the concentration of progesterone in the blood of a pregnant woman. In early pregnancy, progesterone levels are high to maintain the uterine lining. If progesterone levels drop sharply at week 38, what is the most likely outcome?
Hard
- AThe baby will stop growing
- BLabour will begin soon
- CThe placenta will become thicker
- DThe amniotic fluid will increase
16.The graph shows the change in the size of the uterus during pregnancy. The size increases slowly in the first trimester, then more rapidly in the second, and plateaus in the third. Which statement best explains the plateau in the third trimester?
Medium
- AThe baby stops growing
- BThe uterus cannot stretch further and the baby grows by pushing against organs
- CThe placenta stops producing growth hormones
- DThe mother's diet limits growth
17.A pregnant woman is advised to take folic acid supplements. Folic acid is known to reduce the risk of neural tube defects in the developing embryo. During which period is this supplement most critical?
Medium
- AFirst trimester
- BSecond trimester
- CThird trimester
- DAfter birth
18.In an experiment, researchers measured the oxygen concentration in blood from the umbilical vein (carrying blood from placenta to foetus) and the umbilical artery (carrying blood from foetus to placenta). Which set of results would you expect?
Hard
- AUmbilical vein: high oxygen, umbilical artery: low oxygen
- BUmbilical vein: low oxygen, umbilical artery: high oxygen
- CBoth have the same oxygen concentration
- DUmbilical vein: no oxygen, umbilical artery: high oxygen
19.A pregnant woman's blood volume increases by about 50% during pregnancy. Which of the following is a direct benefit of this increase?
Medium
- AIt reduces the risk of high blood pressure
- BIt allows more oxygen and nutrients to be delivered to the foetus
- CIt prevents the mother from becoming anaemic
- DIt decreases the workload on the heart
20.A foetus at 24 weeks has a heartbeat of 140 beats per minute (bpm). At 40 weeks, the heartbeat is 120 bpm. Which is the most likely explanation for this decrease?
Hard
- AThe foetus is becoming less active
- BThe heart is growing larger and pumping more efficiently
- CThe mother's heartbeat is slowing down
- DThe placenta is failing
21.The diagram shows a foetus in the uterus. Which labelled structure is the amniotic sac?
Easy
- AA
- BB
- CC
- DD
22.The diagram shows a developing foetus. What is the function of structure X (the umbilical cord)?
Easy
- ATo protect the foetus from bumps
- BTo connect the foetus to the placenta
- CTo produce amniotic fluid
- DTo hold the foetus in position
23.A study tracked 100 pregnant women and recorded the number of foetal movements per hour in the third trimester. The average number of movements was 30 per hour. Which conclusion is most valid?
Hard
- AAll foetuses move exactly 30 times per hour
- BSome foetuses may move more or less than 30 times per hour
- CFoetuses move less in the third trimester
- DMovement is not important for foetal health
24.A pregnant woman has a blood test that shows low levels of α-fetoprotein (AFP). Low AFP can be associated with an increased risk of Down syndrome. This is an example of:
Medium
- ADiagnosing a disease definitively
- BScreening for a potential condition
- CDetermining the baby's gender
- DMeasuring the baby's size
25.A pregnant woman is given an ultrasound scan at 20 weeks. The scan shows that the baby's lungs are not yet mature. In which trimester do the lungs typically mature?
Medium
- AFirst trimester
- BSecond trimester
- CThird trimester
- DAfter birth
26.Which structure connects the placenta to the foetus?
Easy
- AAmniotic sac
- BUmbilical cord
- CCervix
- DFallopian tube
27.A researcher measures the concentration of oxygen in the blood of the umbilical vein and the umbilical artery. Which set of results would be expected?
Hard
- AHigher oxygen in the umbilical vein than in the umbilical artery
- BHigher oxygen in the umbilical artery than in the umbilical vein
- CEqual oxygen in both vessels
- DNo oxygen in either vessel
28.During a pregnancy, the mother's blood volume increases by about 50%. Which of the following is a direct benefit of this increase?
Medium
- AMore oxygen and nutrients can be delivered to the foetus
- BThe mother's heart rate decreases
- CThe foetus can breathe through the mother's lungs
- DThe mother's blood pressure decreases
29.A pregnant woman is advised to take folic acid supplements. Folic acid reduces the risk of neural tube defects. During which period is folic acid most critical?
Medium
- AFirst trimester
- BSecond trimester
- CThird trimester
- DAfter birth
30.In an experiment, researchers measure the concentration of glucose in the blood of the umbilical vein and umbilical artery. Which pattern would indicate that the placenta is functioning correctly?
Hard
- AHigher glucose in the umbilical vein than in the umbilical artery
- BHigher glucose in the umbilical artery than in the umbilical vein
- CEqual glucose in both vessels
- DNo glucose in either vessel
31.A doctor measures the foetal heart rate at 24 weeks (140 bpm) and at 40 weeks (120 bpm). What is the most likely reason for the decrease?
Medium
- AThe foetus is becoming less active
- BThe foetal nervous system matures and regulates heart rate
- CThe placenta is failing
- DThe mother's heart rate decreases
32.What is the main function of the amniotic fluid?
Easy
- ATo provide nutrients to the foetus
- BTo cushion and protect the foetus
- CTo remove waste from the foetus
- DTo exchange gases between mother and foetus
33.A scientist is studying the growth of a foetus by measuring its mass at different weeks. The average mass at week 20 is 0.3 kg, and at week 25 it is 0.7 kg. What is the approximate average weekly mass gain between week 20 and week 25?
Medium
- A0.04 kg per week
- B0.08 kg per week
- C0.4 kg per week
- D0.8 kg per week
34.A pregnant woman's blood test shows low levels of α-fetoprotein (AFP). Low AFP can be associated with an increased risk of Down syndrome. This is an example of:
Hard
- AA diagnostic test
- BA screening test
- CA treatment
- DA genetic therapy
35.A study tracked 100 pregnant women and recorded the number of foetal movements per hour in the third trimester. The average number of movements was 30 per hour. If a woman reports only 10 movements in two hours, what should be the next step?
Hard
- AIt is normal; no action needed
- BShe should contact her midwife or doctor immediately
- CShe should drink cold water and wait another hour
- DShe should count again the next day
36.What is the term for a fertilised egg before it implants into the uterus?
Easy
- AZygote
- BEmbryo
- CFoetus
- DGamete
37.During which trimester does the baby's heart, brain, and other organs begin to form?
Easy
- AFirst trimester
- BSecond trimester
- CThird trimester
- DAfter birth
38.What is the name of the structure that connects the placenta to the baby?
Easy
- AUmbilical cord
- BAmniotic sac
- CCervix
- DVagina
39.Which of the following is a function of the amniotic fluid?
Medium
- ACushioning the baby
- BProviding nutrients to the baby
- CRemoving waste from the baby's blood
- DConnecting the baby to the placenta
40.At what stage does the developing baby become known as a foetus?
Medium
- AAfter fertilisation
- BAfter implantation
- CAt the end of the first trimester
- DAt the beginning of the third trimester

Revision notes

## Pregnancy Revision Notes - **Fertilisation** occurs when a sperm fertilises an egg in the **fallopian tube**. The fertilised egg is called a **zygote**. - The zygote travels to the **uterus** and **implants** into the thickened lining. - **Pregnancy** lasts about 40 weeks, divided into three **trimesters**: - **First trimester (weeks 1-12)**: Baby is an **embryo**; heart, brain, organs form. By week 12, baby is a **foetus** (size of a lemon). - **Second trimester (weeks 13-26)**: Muscles, bones, fingers, toes develop. Baby moves, hears sounds. - **Third trimester (weeks 27-40)**: Rapid growth, lungs mature, baby moves head-down for birth. ### Supporting Structures - **Placenta**: Organ in uterus; provides nutrients & oxygen via **umbilical cord**; removes waste. - **Uterus**: Where baby develops; stretches as baby grows. - **Amniotic sac**: Thin bag filled with **amniotic fluid**; cushions and protects baby, allows movement. - **Cervix**: Lower part of uterus; stays closed during pregnancy, opens (dilates) for birth. - **Vagina**: Passage from uterus to outside; baby passes through during birth.

Zygote: A fertilised egg cell formed when a sperm fertilises an egg.
Embryo: The developing baby during the first 12 weeks of pregnancy.
Foetus: The developing baby from week 12 until birth.
Placenta: An organ in the uterus that provides nutrients and oxygen to the baby via the umbilical cord and removes waste.
Umbilical cord: The cord connecting the baby to the placenta, carrying nutrients and oxygen.
Amniotic sac: A thin bag surrounding the baby, filled with amniotic fluid for cushioning and protection.
Amniotic fluid: Fluid inside the amniotic sac that cushions and protects the baby.
Cervix: The lower part of the uterus that opens (dilates) to allow the baby to be born.
Uterus: The organ where the baby develops during pregnancy.
Fallopian tube: The tube where fertilisation usually occurs.

Flashcards

Where does fertilisation usually occur?

In the fallopian tube.

What is a fertilised egg called?

A zygote.

What happens after the zygote reaches the uterus?

It implants itself into the thickened lining of the uterus.

What is the baby called during weeks 1-12?

In early weeks it is an embryo; by the end it is called a foetus.

What is the baby called after the first trimester?

A foetus.

What develops during the first trimester?

The heart, brain, and other organs begin to form.

What happens during the second trimester?

The baby grows, develops muscles, bones, fingers, toes, and facial expressions; the mother may feel movements; the baby begins to hear sounds.

What happens during the third trimester?

The baby grows rapidly, gains weight, lungs mature, and the baby moves into a head-down position ready for birth.

What is the role of the placenta?

It provides nutrients and oxygen from the mother’s blood and removes waste products from the baby’s blood.

How does the placenta connect to the baby?

Through the umbilical cord.

What is the function of the amniotic sac?

It surrounds the baby and contains amniotic fluid, which cushions and protects the baby and allows it to move.

What is the role of the cervix during pregnancy?

It remains closed to keep the baby inside the uterus.

What happens to the cervix as birth approaches?

It gradually opens to allow the baby to be born.

What is the vagina's role during birth?

It is the passage through which the baby passes during birth.

How long does pregnancy usually last?

Around 40 weeks.

What are the three trimesters?

First trimester (weeks 1-12), second trimester (weeks 13-26), third trimester (weeks 27-40).

What is the size of the baby at the end of the first trimester?

About the size of a lemon.

What does the uterus do during pregnancy?

It stretches and grows as the baby gets bigger.

What is the amniotic fluid?

The fluid inside the amniotic sac that cushions and protects the baby.

Where does the zygote implant?

Into the thickened lining of the uterus.

What connects the placenta to the baby?

The umbilical cord.

What is the cervix?

The lower part of the uterus that connects to the vagina.

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