@devriesj,
Hi Dev,
I don't think we have much imagination generally in this area. Spouse is often 'my better half'.
In less common usage some might say 'trouble' or 'trouble and strife' (rhyming slang for wife).
Kids are usually just kids, but occassionally you might hear:
Anklebiters
Sprogs
And then there are the 'euphemisms' for pregnancy:
Bun in the oven (I've heard premmy babies referred to as half cooked)
Belly full of arms and legs (or paws and claws)