Which hormone is thermogenic and responsible for the rise in basal body temperature at the time of ovulation?

• A. Progesterone
• B. Prolactin
• C. Relaxin
• D. Luteinizing hormone

Answer: (A)

Progesterone is the thermogenic hormone responsible for the rise in basal body temperature after ovulation. Once ovulation occurs, the corpus luteum forms and secretes progesterone, which nudges the hypothalamic temperature set point upward. This causes a modest increase in basal body temperature—about 0.3–0.5°C (roughly 0.5°F)—that lasts through the luteal phase. This temperature shift is what fertility awareness methods track to identify ovulation. Prolactin relates to milk production, Relaxin helps loosen joints and support pregnancy, and Luteinizing hormone triggers ovulation but does not cause the thermogenic temperature rise that follows ovulation.