In which week of pregnancy, brain is formed:
A. 12 week
B. 18 week
C. 20 wk
D. 24 wk
Correct Answer: A. 12 week
Explanation
Question: In which week of pregnancy is the brain formed?
To understand this, remember that brain development starts very early in pregnancy and then continues throughout gestation.
Key concept
- The brain develops from the ectoderm.
- Formation begins with the neural plate → neural tube → brain and spinal cord.
- “Brain formed” in exam questions usually means when brain development begins, not when it is fully mature.
Timeline of brain development
- 3rd week: Neural plate appears
- 4th week: Neural tube forms; brain and spinal cord start developing
- 5–6 weeks: Primary brain vesicles develop
- 8–12 weeks: Major brain structures are identifiable
- Development continues throughout pregnancy and even after birth
✅ Correct Answer: 12 weeks
📌 Exam tip:
If asked “when does brain development start?” → 3rd–4th week
If asked “when is brain formed?” → 12th week
- Advanced development and functional maturation occur, not formation.
Other Options Details
Question: In which week of pregnancy is the brain formed?
Let’s go through all options one by one 👇
A. 12 weeks
- By 12 weeks, the basic structure of the brain is already formed.
- The brain has developed from the neural tube, which begins forming very early (around 3–4 weeks).
- At 12 weeks, the brain is developing and differentiating, but not starting its formation.
- ❌ Not the correct answer for brain formation.
B. 18 weeks
- At 18 weeks, the brain continues rapid growth and maturation.
- Brain parts become more complex, and neural connections increase.
- Formation has already occurred much earlier.
- ❌ Not correct.
C. 20 weeks
- By 20 weeks, the major brain structures are well developed.
- The fetus shows better neurological responses.
- This stage is related to growth and functional development, not initial formation.
- ❌ Not correct.
D. 24 weeks
- At 24 weeks, the brain shows advanced development, especially of the cerebral cortex.
- Brain maturation continues, but formation is long completed.
- ❌ Not correct.
✅ Correct Concept (Important for exams)
- The brain begins to form very early, around the 3rd–4th week of pregnancy, from the ectoderm (neural tube).
- None of the given options exactly match the starting week, but 12 weeks is the closest option, as by this time the brain is clearly formed and identifiable.
🧠 Final Answer for MCQ:
✅ A. 12 weeks
I hope that you liked this article.
Thanks!! 🙏 😊
Writer: Vandita Singh, Lucknow (GS India Nursing Group