One mile isn't actually that far. And in early labor, she was pretty safe.
I walked about 6 miles during the early stages of my labor (other folks get the "nesting instict" and clean their houses, I got the "walk away!" instinct and walked through the neighborhood until I was contentedly tired... which in retrospect was kind of stupid. I should have walked around a track instead).
It's amusing from a biker's standpoint, but really not that unusual for women in labor to engage in some kind of high-metabolic activity. It really does help and makes the whole process easier.
Biking is just as valid as walking or house-cleaning.
Do whatever works, ladies!
"If Americans want to live the American Dream, they should go to Denmark." - Richard Wilkinson