LH surge occurs
A. 24 hours after ovulation
B. During ovulation
C. 24 hours before ovulation
D. 4 days after ovulation
Correct Answer: C. 24 hours before ovulation
Explanation
LH Surge Occurs: Explanation
The LH (Luteinizing Hormone) surge occurs about 24–36 hours before ovulation in a normal menstrual cycle. It is a rapid rise in LH secretion from the anterior pituitary gland.
Why does LH surge occur?
As the Graafian follicle matures, it produces a high level of estrogen. When estrogen levels reach a threshold, it triggers the pituitary gland to release a large burst of LH — called the LH surge.
Effects of LH Surge
It causes rupture of the mature Graafian follicle
It releases the ovum (egg) → Ovulation
It triggers formation of Corpus luteum, which begins secreting progesterone
Timing
Event Approx Day in 28-Day Cycle
LH Surge Day 13–14
Ovulation About 24–36 hours after LH surge
Clinical Importance
Used to predict fertile window
Measured in urine ovulation kits
Helps in assisted reproductive techniques
In Summary
> LH surge occurs 24–36 hours before ovulation and is triggered by high estrogen levels. It causes rupture of the follicle and release of the egg.
Other Options Details:
Here is the explanation of all the options:
Question context:
These options are usually related to the best time for fertilization or pregnancy and sperm–ovum viability.
A. 24 hours after ovulation
After ovulation, the released ovum (egg) remains viable only for 12–24 hours.
Therefore, fertilization may still be possible within 24 hours after ovulation.
However, the chances gradually decrease as time passes.
B. During ovulation
During ovulation is the time when the ovary releases a mature ovum into the fallopian tube.
This is the most fertile period because the egg is fresh, and if sperm is already present, fertilization can occur immediately.
So, this is considered the best time for conception.
C. 24 hours before ovulation
Sperm can live in the female reproductive tract for 2–5 days.
If intercourse happens 24 hours before ovulation, the sperm will be waiting in the fallopian tube when the egg is released.
This also gives a high chance of pregnancy, sometimes even better than during ovulation.
D. 4 days after ovulation
4 days after ovulation, the ovum is no longer viable.
The egg disintegrates within 24 hours if not fertilized.
Thus, fertilization cannot occur and the chance of pregnancy is almost zero.
Summary
Timing Chance of Fertilization Reason
24 hrs before ovulation Very High Sperm survives and waits for the egg
During ovulation Highest Egg freshly released
24 hrs after ovulation Moderate Egg still alive but aging
4 days after ovulation Almost Zero Egg already degenerated