Aggression in cats

Question
My cat has suddenly started to be aggressive to her 6 month old Male kitten and female kitten. She has also started growling at us if we pick her up or touch her tummy.  Could this be early signs of pregnancy? The vet can not feel anykittens as yet but couldnt feel them when she was pregnant before.  She has always been a very affectionate and tolerant cat with both us and her offspring?  The vet says she is very healthy and has no other signs of illness.

Answer
Martyn,

Since your animal has been vet checked before seeking my advice I would have to conclude that your cat may very well be showing signs of early pregnancy. In fact, I am surprised that she waited 6 months to get pregnant. If she is showing signs of early pregnancy it is best to leave her be....She may need more rest than usual...You likely won't know the day when she became pregnant. The approximate gestation period is in 62-65 day range sometimes give or take a few days. I should also in good conscience add that if you do not intend to keep the kittens backyard breeding is not a wise idea. It is much more responsible and cost effective to spay your cat and prevent further litters of kittens which could end up in animal shelters. If you have any further questions or concerns please do not hesitate to contact me.