I have a baby, and a cat. Our cat likes to leap up on you and sit on you etc, as do many house cats, you just need to keep the cat away from the baby in these circumstances, to make sure that the cat does not pounce on the baby. Also make sure the cat knows that babys bedroom is out of bounds. For outside, you can buy a mosquito net to cover the baby in the pram, which acts as a barrier and the cat, well my cat, does not jump up into the pram at all.
Never leave the cat alone in a room with the baby, althought your cat will mean no harm, they could accidentally scratch or frighten your baby.