People used to take their babies and toddlers out in prams all the time, but these days they don't. Instead, they use pushchairs, baby buggies, strollers or whatever you want to call them, mainly because these fit in cars whereas prams don't. Strictly speaking, you can still perambulate with them, but they're no longer what you'd call prams (or baby carriages, if you're a North American reader and have no idea what I'm talking about).
This makes the following picture of the scene outside Essex University's nursery school all the more bewildering:
They always have at least ten prams outside, but never any pushchairs.