The two most common causes of death are as follows: 
1. Due to the cold weather, kittens born in winter have a very high mortality rate, especially kittens born to stray cats. Without proper insulation, they are likely to freeze to death.
2. Insufficient nutrition: A mother cat usually gives birth to 3-5 kittens in one litter. One or two of these kittens may be born weak. These kittens are likely to not get enough milk and will gradually weaken and die.
Therefore, kittens need more careful care in the first two weeks after birth, ensuring a suitable indoor temperature. If a kitten is found to be very weak, artificial feeding can be considered.
