As with human pregnancies, cats don't necessarily give birth exactly on cue. At some time between 60 and 65 days from the time of conception, your cat will begin to become restless in preparation for the birth. At this stage, you should remove the blanket from her bed (it may hide a kitten later) and carefully place your cat there. The next stage is up to her - you're probably more nervous than she is!
Once her contractions start, she should lie down on her side, though she may get up and move around at any time during labour. With the birth of the kittens about to happen, you will probably not need to do a thing - unlike human deliveries, cats are usually very capable of looking after themselves. A few reassuring words as she gives birth will help keep her happy.
The arrival of the first kitten may come at any time between 10 and 60 minutes after the contractions start. The kittens will be delivered one at a time, emerging along with the placenta. Most kittens are born head first, but around one third are born legs first. Whatever the case, a healthy cat should not usually have problems.
On extremely rare occasions, a kitten may not be fully born five minutes or so after first emerging. This is not usual, but if the mother shows some signs of distress at this point, you should contact your local Veterinary Surgeon. Remember: this is unlikely to happen; most cats experience no difficulty in giving birth.
Immediately after the birth of each kitten, the mother will bite through the umbilical cord and attempt to eat the placenta, which should emerge after each kitten. This is quite normal. Some Veterinary Surgeons and breeders remove the placenta before the mother eats it, as it may cause indigestion later on. If your cat doesn't mind you removing the placenta, you might like to take it out of her way. Otherwise, leave well alone. Mother knows best.
Normally, the sac which contains each kitten in the uterus will break as the birth is taking place. If a kitten is born with its sac still sealed (which is very unlikely), and the mother shows no interest in breaking it, you should tear it with clean hands and encourage the mother to lick the kitten.
The time between the birth of each kitten may be a matter of minutes, or over an hour. Much more than this, and the cat may be having difficulties. If in doubt, call your local Veterinary Surgeon. Usually, the birth of all kittens takes place without a hitch.