Pregnant cats are more than capable of taking care of themselves. But needless to say, there are a few things you should know to make sure everything goes as smoothly as possible.
Leading up to the birth
During your cat's last week of pregnancy, make sure she is kept away from other pets and children: females in late stages of pregnancy can get aggressive. Try to keep her as calm and inactive as possible during this time, and try to get her accustomed to the maternity bed.
You can create a maternity bed out of a cardboard box at least 2 feet x 3 feet and about 1 1/2 feet high. Preferably, the box will have a top to help keep the new born kittens warm and safe, plus a hole in one side that is large enough for mum to crawl in and out of. Place a few inches of shredded newspaper in the bottom of the box and cover with a blanket or old shirt. Finally, make sure to place the box in a warm and quiet place.
It's best to try to get your cat accustomed and comfortable with this special bed. Cats naturally look for an area where they can deliver their kittens, so without a maternity bed they will find another suitable place - which could be the bottom of your wardrobe!
The birth
When your cat is ready to give birth, she will become very restless, pace as if she is looking for something, and become very vocal. She also might make many unproductive trips to the litterbox, but eventually will settle into her maternity bed.
If she is not well accustomed to her bed, however, she may choose another suitable spot. Don't move her or make her use the maternity bed if she doesn't want to. It's always safer to let her give birth where she chooses.
Once she settles into her spot, she will go into labour, which can last for up to 12 hours. During this time you should prepare for the birth by getting a bowl of warm water, clean towels and cloths, dental floss and petroleum jelly together.
If the mother screams as the first kitten is born, don't be alarmed. This is normal, especially for a first time mum. Some kittens will born head first (like human babies), but others will appear feet first - again, this is quite normal. Kittens normally come at 30-45 minute intervals, even over one hour between deliveries. Stand and watch at a safe distance, and only intervene if absolutely necessary, for example if you see her straining excessively without producing a kitten, or if there is a bloody discharge when the vet should be called in.
The delivery
Once the kitten is born, the mother will break the amniotic fluid. If not, you may need to help tear the sack using a towel (never a sharp object), so the kitten can breathe.
After each birth, the mother will eat the placenta and clean every kitten. This is important maternal behaviour, necessary for the bonding process. However, if she fails to remove the membranes from the kitten's face, you will have to step in. Gently clean it away from the mouth and nose, then quickly dry the kitten against the grain of the hair using a clean cloth (facecloths work well because they're big enough to cover the kitten but won't get in your way). Finally, firm rubbing with a warm cloth will dry and warm the kitten, and also stimulate it to take its first breath.
Mum will also bite through the umbilical cord, but your help will be needed again if she doesn't. Just tie dental floss around the cord about 1 inch away from the kitten's body, and cut the umbilical cord on the mother's side of the tie. Don't cut it too close to the kitten, as this may cause infection or even death. If you notice the mother trying to chew too close to the kitten, stop her and do it yourself.
After the birth
The entire delivery generally takes between 2-5 hours, but can last up to 12 hours. If you notice the mum having trouble giving birth at any time, put some petroleum jelly on her to ease the kittens' passage. If your cat appears to be straining unproductively for an hour or more during the birth, contact your vet.
Litters are usually of between 4 and 6 kittens, although litters of just one or two can be common. Once all the kittens are born, let your cat take care of the rest. But if she doesn't seem to be taking care of her kittens, you may need to take over - and consult your vet immediately.