My bloody cats keep bringing me bloody (sometimes literally) live mice, birds and rat babies. 
Very insistent that I take them.
Two of them (the cats) have practically velcro-ed themselves to my side, and come and sit with me and pat me gently when I'm throwing up. Pretty sure they think the baby is one of theirs.
Their odd behaviour around me was one of the reasons I took the pregnancy test in the first place.
Guessing they can either tell I am not 100% as I am in bed a lot, or they can smell the hormonal changes and are acting on instinct.
Anyone else have pets that 'know' something is up, and have been acting weirdly since you got the BFP?