Lost a kitten. Why?

..I've recently just had a newly born kitten die!..

You need to tell us more. How many kittens were in the litter? How much did the one that died weigh?  How is the mother treating the kittens? Without some information, no one can give you advice.

There was 4 but it was stuck inside her so we took her the vets they did. C section, that one died so there were 3 healthy kittens, they were fine then just about 30 minutes ago I noticed one was lying by its self & wasnt breathing properly then suddenly it just pasted away

Im struggling to come to terms with how he just died, I did everything right made sure they were always ok & the mother not sitting on them

Was mom spayed during the c section as well? Are you sure she is producing milk?

Sometimes momma cat sense something is not right with a kitten, and she will push it out of the nest and abandon it. It sounds like this is what happened to your kitten. There's nothing you could have done. With the two others, make sure they latch onto momma's nipples and stay close to her. Kittens can't regulate their temperature, so they need to be close to stay warm. You could help with this by filling a sock with raw rice and heating it in the microwave. Cover it with a towel and place it near the kittens.  If the kittens don't nurse, you will have to supplement. 

There is tons of advice on this site about how to care for kittens, and I'm sure other members will help you also.

Yes she was spayed too & yes she is producing milk, as the other 2 are perfectly fine

I am so sorry for your loss, but sadly this sometimes just happens. It would be a good idea to weigh the others each day with a small scale so you know they are gaining weight on a regular basis. Do they seem happy, sleeping and feeding well? Does the mother look after htem well? If a kitten seems restless or cries a lot then that is a sign something is wrong and you need to intervene. If you have not already got it all, then get some KMR (kitten replacement milk) and a bottle and syringe from a pharmacy or good pet shop and keep it to hand in case you need to supplement their feeding. It is devastating to lose a kitten, and I am sure you will want to ensure the others thrive.

I would really recommend weighing them daily. Since she was spayed, her hormones are not typical and there may be some issues with her milk production. You may want to supplement the kittens if they are not gaining.

The other issue is that the kittens were placed under anesthesia with mom. This puts their tiny bodies at a disadvantage.

Thanks for all your advice, it means a lot!, im truelly saddened that shes lost a kitten, I dont think she push him out the nest he sort of just wasnt breathing properly & didnt seem very motive, I just cant come to terms with how he died he was all suckling & moving like the others then just changed & died, I tryed everything to resuscitate him & save him but couldnt, im more not happy with the vets surely they should have checked the kittens were healthy.

Sometimes they are healthy and they still don't make it. I don't think anyone is at fault here, but I really am sorry.

Ino ino, im just so so gutted this has happened, I didnt even hardly get much sleep last night because I was back & forth checking them, so so I had to burey him in the back garden

Also is it best to watch the mother doesnt sit on the kittens incase she suffocates them?

It's unlikely that will happen. It's always best to keep an eye, but you can't possibly watch them all the time. Mom has excellent instincts and babies will squirm out of the way if they are too warm.

Do you think that the kitten that died the mother could of crushed her ribs possibly, thats why he wasnt breathing properly

No, I don't think that's what happened here. It sounds like its body shut down, and that there was something wrong that you couldn't see.

It was so so sly, just wish I could have done something

I agree with TalkingPeanut.  The kittens fate was already decided...  So it may be. Its why cats gets so many kittens, the Nature knows not all do survive even if the conditions are good, alike a good owner / caretaker.

Awww ino its just probably me just trying to work out how it died, when its fate was already decided, it just happened so fast, one minute it was ok the next it wasnt moving

Would you say I need to keep waking up every couple of hours to check them or will they be ok if I just sleep like normal