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Medicine

Hormonal Feedback Loops in the Menstrual Cycle

Quick fact

The same hormone—estrogen—exerts negative feedback at moderate levels, but when it rises above a threshold for about 36 hours, it flips to positive feedback and triggers a massive LH surge that releases the egg.

Why this is interesting

Your body runs on a thermostat-like system—but one that suddenly flips into reverse just before ovulation. How does the menstrual cycle use feedback to control fertility?