The dwarf hamster get sex at least once in a week and their heat period continue for 6-8 hours. So after giving birth, mom hamster can be pregnant within 3hours. The heat period of the hamster is 6-8 hours in a week.

 Hampsters as well as a lot of rodents will be able to breed right after having a litter though it is not at all healthy for her. Hamsters and rats (i breed rats) come into heat every 3 days and will remain in heat for that 3rd day. Until your hamster has weened her babies (about 5 weeks) keep her away from males. If she becomes pregnant while she is still nursing her litter it can be costly on her heath and could possibly miscarry or die in the birth of the next litter.