Problems in using basal body temperature recordings in an infertility clinic

Objective

To determine the degree of accuracy and consistency with which a group of observers could assess basal body temperature recordings in infertile patients.

Subjects and methods

A group of gynecologists, who were considered clinical experts in interpreting BBT charts, and a group of 'non-experts', general practitioners, junior hospital staff and technicians who do not regularly interpret BBT charts clinically, were asked to score 60 temperature charts drawn at random from the hospital records. The accuracy of the predictions could be assessed as full hormonal profiles had been obtained for each of the charts.

Charts from 60 normal and infertile women were evaluated to determine:

a) if the cycle was ovulatory;
b) if the cycle was from a normal woman, from an infertile woman or one in which conception occurred;
c) the day on which ovulation occurred.

Results

The 'expert' group obtained slightly better results than the 'non-expert' group, but neither group did particularly well.

About 80% of the temperature charts were correctly interpreted by both groups as being either ovulatory or anovulatory, but only about half were correctly interpreted as being from a normal, infertile or a pregnant woman.

In ovulatory cycles, the day of ovulation was predicted correctly for only about 44% of the charts.

Conclusion

"Predicting the day of ovulation from temperature recording, particularly in infertile women, is clearly unjustified."