What do you need to have a baby in Fable 3?

Get married to a member of the opposite sex. The fastest way to have a baby is to go to the book shop in Bowerstone market and buy the "come hither dear" book. This will allow you to proposition your partner into bed. After the propositioning, he/she'll follow you to a bed where you can choose to have protected or unprotected sex. Chose unprotected and you or your partner will get pregnant depending on your gender.
press circle.