A Note About Breeding:
Breeding your hamster is not a decision to make lightly and you absolutely must consider what you will do with any babies that result. Most pet stores have established suppliers already and there is no shortage of hamsters available. You should also carefully consider the temperament and health of the hamsters you are breeding. However, the information here may be helpful if you find yourself with a pregnant female by accident, or perhaps from the pet store.
Age of Sexual Maturity:
Roborovski hamsters may reach sexual maturity as early as 5 weeks of age, but usually do not breed for the first time until they are older. Females should be bred for the first time when they are closer to 4 months old (males can be bred by 3 months of age).
Female hamsters come into estrus (heat) every 4 days or so (this is the time they will be fertile and receptive to a male).
Length of Pregnancy:
The gestation period of Roborovski hamsters is usually 20-22 days but can vary up to 30 according to some sources.
Litter size is usually small; typically there are 4-6 pups per litter (though larger litters have been reported).
Age of Weaning:
Roborovski hamsters can be weaned at 21 days; this is a good age to separate male pups from the female pups.
Roborovski hamsters are considered more difficult to breed than Russian dwarf or Syrian hamsters. They may be more likely to breed only in spring and summer months and a female might not have her first litter until her first spring.