My grandfather has an ancient wheelbarrow in his yard, a device that has to be at least two decades older than me. I took a picture of the rusty cast iron wheelbarrow this afternoon, and I hollowly chuckled when he referred to the garden implement as an "Irish baby carriage."
Yet my grandfather seemed puzzled at my amusement, and to his ears the term "Irish baby carriage" was simply an out-of-date expression. I found the phrase of course to be a demeaning commentary on the historic poverty of the Irish, for whom a wheelbarrow would have been an important possession in the harvesting of potatoes. Thus, an "Irish baby carriage" would imply that poor Irish peasant women dragged along their infants in the potato fields as they tended their meager crops, or as they traveled to their Philadephia jobs.
At least, that is how I interpreted the origin of term "Irish baby carriage."