I am wondering because I have never owned a female kitten of when they got into heat and what are the signs of impending heat cycles.. I am the owner of a four month old female kitten and she has become quite the escape artist as of lately.. I read online that they become more loving but she has always been very social and loving and very people orientated since we got her.. she got out about a week ago over night and well when I discovered that she was gone I stayed out in the desert heat until I found her.. she slept for days when she first came back but when she was awake she was still trying to get out.. her belly is now swollen and she scratches me when I touch it.. she had scratches on her face and was cleaning herself more than usual after I found her.. but isn't she too young to be in heat cuz she just turned four monthes old.. I was wondering if anyone could help me with this cuz I couldn't find anything online that helped me much.. thanks for your time.. T

Cats generally start their first heat around 6 months of age but always it could be earlier. I doubt as early as when she got out, unless you are in any doubt as too her age. Cats can be spayed as soon as they weigh at least 2 lbs, most vets recommend at 4 months of age. So this seems like the perfect time to spay her!
Cats in heat are more affectionate in a purely self-seeking way. Not just cuddling on your lap or rubbing its head on your hand for attention, they will throw themselves at your feet and roll belly up and will not let you past them without being petted. Very demanding! Also, even the most quiet cats get quite vocal, especially when you are trying to sleep at night. They will meow constantly at nothing, or yeowl. Not all cats get vocal, but most do. Also you will notice them bathing their vulva extra much, and if you care to look close, you would notice it will be secreting clear fluid. And of course they try to make a grand escape, to find a mate.
Many cats have a silent first heat, and you won't know until its to late they are in it, and by the time you notice these signs, they probably have been in it for a while. If their is any chance of her getting out at all, she will, and any male cat in the vicinity will be upon her. So for saftey's sake, do not dely in get her to the vet for her spay.

Thats funny, my male cat has the same symptoms, except for the clear fluid and vulva thing. He's just an attention whore though! LOL. His favorite time to demand attention is when I'm asleep. He'll lay on my head and lick my face, then he will butt his head against my hand, trying to get me to pet him. I think he may be in heat constantly! LOL

What breed of cat is this? I have never heard of a cat going into heat at 4 months of age. I guess it's not impossible, but I find it highly unlikely.

It is also possible that the cat is older than the OP realizes. If the cat is just a small size, then it may be older than four months.

To the OP, do you know when the litter was born?

If her belly is swollen and she scratches you when you touch it that is not the normal signs of a pregnant cat. When my cats are expecting, they LOVE to have their bellies rubbed and scratched. I think you have something else going on here besides a pregnant cat and a trip to the vet would be in order in my opinion.