There are heaps of shortened versions of names that I think suit little kids better, or I just don't like the actual name but I love the nickname, but I'm the type that would put the full name on the birth certificate and then just use the shortened version. I think for me, I say to myself, 'What if the child doesn't like the 'kid' version when they get older?' or 'What if they end up in a professional sort of job and want a more 'serious' name in order to be taken seriously by colleagues/clients/employers etc?'

Then there's always the situation where you love the nickname, but it doesn't 'flow' so well with your surname but the long version does.

My prime example is the name Katherine - not a big fan of 'Katherine', but I LOVE Katie and wanted to use it for one of the girls (DH didn't like it so it was out). But Katie can sound quite juvenile, so I thought if I put 'Katie' on the birth cert, she might want a more formal name later in life. And, Katie and Kate just don't go with our surname, but Katherine sounded lovely with it.

If that makes any sense...

I also find it really annoying that BIL's name on his birth cert is 'Chris' - not Christopher or Christian. Just Chris. It's a pain for when I'm cranky with him or am about to launch into a lecture hahaha - 'Chriiiissss...' just doesn't have quite the same ring as 'CHRIS-to-pheeerrrr...' lol. I would have liked it better if his parents had put Christopher on the birth cert and then just called him Chris hahaha.