Table 2 Threshold effect analysis of E₂ level (100pg/mL) on the clinical pregnancy rate

Model I (linear)

OR

95% CI

p value

Linear effect

0.986

(0.980, 0.992)

< 0.001

Model II (polyline)

OR

95% CI

p value

Predicted threshold (K, E ₂ level, 100pg/mL)

14

Effect 1 (< K)

0.975

(0.960, 0.989)

< 0.001

Effect 2 (> K)

0.999

(0.983, 1.015)

0.907

variability of effectiveness

0.172

(0.019, 0.324)

Logarithmic likelihood ratio test

0.042