MyPetEd explains that there are many potential causes of shaking in a kitten, although the most common cause is low body temperature. Like people, kittens shiver when they are not warm enough, so they should be kept at a steady temperature of 80 degrees Fahrenheit until they are 28 days old and at least 72 degrees after that.
Cat World notes that kittens, especially newborns, are unable to regulate their body temperatures like adult cats, so a shaking kitten is likely in need of a warm blanket and a cozy area to rest and warm itself. PetMD notes that tremors are a fairly common occurrence in cats and can mean anything from a low level of glucose in the blood to fear or trauma. In rare cases, tremors may also be a sign of toxicity or a neurological issue. VetInfo also provides multiple potential causes of feline trembling, including hypothermia, digestive problems, psychological issues such as stress and anxiety, seizures and shock. The website explains trembling is quite common with feline seizures, but the action tends to be violent and noticeably different from the type of shaking that occurs with a scared cat or one whose body temperature is too low.