Table 4.

Multivariate regression analysis of confounding factors according to present analysis (forward elimination model)

	B	P	Exp(B)	95% CI of Exp(B)
				Lower bound	Upper bound
Age	0.11	<0.001	1.12	1.07	1.16
BMI	0.10	0.001	1.11	1.04	1.17
HDL	−0.51	0.02	0.60	0.40	0.91
Baseline E2	−0.01	0.02	0.99	0.98	1.00
Progesterone on hCG day	0.55	0.02	1.74	1.09	2.78
Blastocyst transferred (yes or no)	0.45	0.009	1.56	1.12	2.18
Constant	−6.43	<0.001	0.002

We added factors that were significantly different in the univariate analysis of baseline characteristics and characteristics after stimulation: age, BMI, waist-to-hip ratio, HDL, baseline E2, progesterone level on hCG day, and whether blastocysts transferred into this kick-out model. The waist-to-hip ratio was ruled out from the final regression model.

Abbreviations: BMI: body mass index; E2: estradiol; hCG: human chorionic gonadotropin; HDL: high-density lipoprotein.