Cats like routine and any disruption to this can be unsettling. They feel part of the family and if a new member of the family is brought in, this can cause a change in behaviour. This can include being withdrawn, going off outside or in quiet areas of the house or even spraying their scent to mark their territory. They can get quite disturbed by new smells and sounds and lots of visitors. There have been a few reported incidences of smothering babies, so I would recommend that you do not leave your baby unattended in a room with a cat.