How can basal body temperature (BBT) monitoring indicate ovulation?

• A. BBT typically rises by 0.3 - 0.6°C during ovulation
• B. BBT drops during ovulation
• C. BBT remains unchanged around ovulation
• D. BBT rises by 2–3°C after ovulation

Answer: (A)

Basal body temperature rises after ovulation because progesterone from the corpus luteum thermally elevates the body's resting temperature. The change is modest, typically about 0.3–0.6°C, and it creates a noticeable shift from the cooler temperatures of the follicular phase to a sustained warmer temperature during the luteal phase. This biphasic pattern indicates that ovulation has occurred and the luteal phase has begun, helping confirm that a complete ovulatory cycle has taken place. The rise is not a large spike like 2–3°C, and it does not occur before ovulation; readings should also be taken at the same time each morning to be reliable.