I've seen ads for baby extras, twins under 3 months etc.

Martin: Uh, Sir, why don't you just use real cows?
Painter: Cows don't look like cows on film. You gotta use horses.
Martin: Uh, Sir, why don't you just use real cows?
Painter: Cows don't look like cows on film. You gotta use horses.
Ralph: What do you do if you want something that looks like a horse?
Painter: Ehh, usually we just tape a bunch of cats together.
-- Clever film techniques, "Radioactive Man"
Just right for the barbecure if you ask 8ball![]()

The majority of them look more like six months or so. You don't really realise this til you've had kids...
A colleague just brought her one and a half month old into the office. Damn, I could have kidnapped her and started a whole new career as a baby wrangler for films![]()

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They usually look like they are just about to spout their first words whilst being held upside down and splattered with fake uterus bits.
Exactly!
Of course, as you say, there are a few which genuinely do look newborn or as near as damn it...