Approximately on which cycle days does the LH surge occur?

• A. Cycle day 11-13
• B. Cycle day 14
• C. Cycle day 5-8
• D. Cycle day 1-6

Answer: (A)

The LH surge is the trigger that brings about ovulation. It happens when rising estrogen levels from the maturing follicle switch to positive feedback on the pituitary, causing a sharp spike in luteinizing hormone. This surge typically occurs about 24 to 36 hours before ovulation. In a standard 28-day cycle, ovulation occurs around day 14, so the LH surge is usually around days 11–13. The egg is released shortly after this surge. So, days 11–13 best fit the timing of the LH surge. Early days (1–6) are menstrual/early follicular phases, and day 14 is the ovulation moment itself, not the surge.