Turns out warr beat me to it, but here's a bit more information.
Warr2098; What is CC?
I'm not warr, but CC comes in Three Forms. It is also short for "Custom Content".
EA CC: These are items that were created by EA and can be found at
www.store.thesims3.com. They are not perfect, but considered more stable than 3rd Party CC.
EA Partner CC: These are also created by EA, but are promotion items for a partner, like the Dr Pepper Promotion.
3rd Party CC: If someone doesn't specify what CC they are talking about, you should assume it's 3rd Party CC. These are items created by someone other than EA, which are uploaded to sites like ModTheSims. It's usually stable, but some CC can be dangerous to your game. My main file is Mod infested, pretty much, but I only have a few CC items, because they can damage your game.
A bit off-topic, but Pam, Rose, and warr asked if it was CC because of the baby stretching issue. Usually, toddlers are stretched if they wear clothing
designed for Adults, but
categorised for all ages, which means it may be there for Adults, but the creator messed up at a step and made it available for everybody.
Hope this helps.