Hamsters reproduce in litters of four to 12 pups with females giving birth an average of two times during the course of their lives in captivity and losing the ability to reproduce at around 1 year of age. Hamsters' ability to care for their young is very fragile and if anything occurs to upset that delicate balance, the mother may kill her own pups.
A female hamster is ready to breed at just a few weeks old, though responsible breeders wait until 4 months to ensure the hamster's health and well-being. Gestation lasts 16 days and birth usually happens at night in coincidence with the hamster's nocturnal habits.
Once the babies are born they must be left alone with their mother. Any human interference, especially human touching of the pups, could lead the mother to kill them for reasons not fully understood. Mother hamsters will also kill their young seemingly at random or if there is a famine and food or water is hard to come by.
Pups mature quickly and should be separated at an early age. Hamsters need their own territory and should not share cages, especially if they are of different genders, as females are larger and more aggressive and will kill males without provocation.