How long does it take for a baby to grow up on The Sims Bustin Out?

Basically it takes about 3 to 4 days depending on how much charisma you have. The charisma also affects how long the baby stays asleep. So, to be sure, when you decide to have a baby make sure you have at least 5 charisma (I speak from experience)

Glad to help! Bye ^_^