Table II.

Summary of results of multivariate logistic regression analyses for a systematic parturition induction program in long gestation Holstein cows (> 282 days of gestation). Data expressed as OR, (95% CI) and P-value. P-values highlighted in gray are > 5% level of significance tested, but risk factors were kept because they improved the fit of the model

Outcome variable	Risk factors
	Induction	Primiparous cows	Difficult calving	Stillbirth	Conceiving again	Culling (reproductive)	Season
							2	3	4
Difficult calving	1.07	3.33		6.95
	(0.54, 2.14)	(1.92, 5.77)		(3.93, 12.30)
	0.844	< 0.001		< 0.001
Stillbirth	0.8	2.46	6.95
	(0.44, 1.45)	(1.47, 4.11)	(3.93, 12.30)
	0.457	< 0.001	< 0.001
Cows conceiving again	1.41					0.08
	(1.05, 1.88)					(0.05, 0.14)
	0.020					< 0.001
Deaths due to post-partum problems	0.35 (0.08, 1.52)		5.8 (1.35, 24.98)
	0.162		0.018
Culling due to reproductive reasons	1.11 (0.70, 1.75)	0.37 (0.18, 0.75)			0.08 (0.05, 0.14)		0.7 (0.33, 1.47)	1.33 (0.69, 2.56)	1.73 (0.99, 3.03)
	0.663	0.006			< 0.001		0.342	0.397	0.054

OR — odds ratio; 95% CI — 95% confidence interval

Seasons: (reference) 1 = Dec, Jan, and Feb

2 = Mar, Apr, and Jun

3 = Jul, Aug, and Sep

4 = Oct, Nov, and Dec