Is my cat pregnant!!!!?????

[pindy]

How can you tell if a cat is pregnant? I'd like to know before the kittens arrive if possible

My 2 are so close they even sleep with there arms round each other, if she is in season, they are bound to of done it - terrible what with them being brother and sister too . If they have and she is, the kittens will be absolutely beautiful, they are both black and white (a bit like felix) so I may have some available too. Here's hoping not