Variable

d. f.

Parameter estimate

SE

Hazard ratio

p-value

Stillbirth vs. live calf

1

0.36

0.07

1.37

<0.001

Multiparous vs. primiparous

1

0.70

0.04

2.00

<0.001

Assisted vs. unassisted

1

0.18

0.08

1.14

<0.04