Exam

Basal Body Temperature

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Basal Body Temperature

  • Indication
  1. Ovulation Indicator
  • Technique
  1. More accurate Thermometers are available for BBT
  2. Take central Temperature same time daily at mid-cycle
    1. Oral or
    2. Rectal or
    3. Vaginal
  3. Start Temperature reading several days before Ovulation
  4. Continue readings for at least 12 Luteal Phase days
  5. Plot on Temperature curve
    1. Y-Axis: Temperature from 97 to 101 F in 0.1 steps
    2. X-Axis: Days of the Menstrual Cycle
  6. Record days of coitus and menstrual days
  • Interpretation
  1. Temperature rise of 0.3 to 1.0 F signals Ovulation
  2. Ovulation usually occurs 24 hours before rise
    1. Helpful retrospectively
    2. Not useful for conception during current cycle
  3. Plotting 2-3 cycles is all that is required
    1. Confirms Ovulation
    2. Approximates Ovulation days
  • Efficacy
  • Inaccurate method
  1. Ovulation could occur 6 days before BBT nadir
  2. Ovulation could occur 4 days after BBT nadir
  • References
  1. Guermandi (2001) Obstet Gynecol 97:92-6 [PubMed]