A comparison of methods to interpret the basal body temperature graph

Area of Science:

• Reproductive endocrinology
• Biostatistics
• Medical informatics

Background:

• Basal body temperature (BBT) charting is a method used for fertility awareness and tracking ovulation.
• Accurate identification of the BBT shift is critical for interpreting fertility cycles.
• Standardized criteria for BBT shift interpretation are needed for reliable analysis.

Purpose of the Study:

• To evaluate and compare different methods for determining the basal body temperature shift.
• To identify the most reliable method for concurrent and retrospective BBT chart interpretation.
• To establish uniform criteria for computer-assisted BBT analysis.

Main Methods:

• Analysis of 8496 BBT charts using specifically coded criteria for uniform computer interpretation.
• Comparison of several methods for identifying the BBT shift, including a 0.3°F rise over three days and curve smoothing techniques.
• Evaluation of temperature averaging and curve smoothing for identifying shifts in complete temperature readings.

Main Results:

• The method defining a shift as 0.3°F or more above the running low average for at least three consecutive days demonstrated the best concurrent chart interpretation.
• A curve smoothing method, creating a line that transects the average of all temperatures on a completed graph, proved effective for retrospective analysis.
• Both temperature averaging and curve smoothing techniques successfully identified a BBT shift in over 95% of charts with complete temperature data.

Conclusions:

• A specific, quantifiable criterion (0.3°F rise over 3 days) is recommended for concurrent BBT shift identification.
• Curve smoothing offers a reliable retrospective method for analyzing BBT shifts.
• Standardized methods enhance the accuracy and consistency of BBT charting interpretation for fertility awareness.