The length of gestation in cats is 63 days from the time of ovulation. Within 12 to 36 hours of giving birth, a queen’s temperature will drop, usually 24 hours before giving birth. The cat will usually start showing some nesting behavior like seeking out a secluded spot to have her kittens earlier. Another signs could be behavioral changes such as restlessness, anxiety and panting, eating refusal, shivering and occasionally vomiting. When this happened, you can start to prepare a nice box or bed with good nesting materials like shredded disposable baby diapers and put it in quite secluded and calm spot. Any disturbances should be avoided.