As the female comes into heat, she will begin assuming a breeding stance with her back swayed and body stretched out. When petted over her back she will remain motionless and sway her back even further. A thin mucus will be noticed coming from her vulva. For breeding, place the male into the female's cage about 1 hour before dark. Closely observe the pair for mating activity or fighting.
Females can be very aggressive toward males and can cause serious injuries.
Remove the male shortly after a successful mating has taken place. It is recommended that the cage be cleaned 2 weeks following breeding so it is clean when the babies arrive. Length of pregnancy is short in hamsters, lasting only 15 to 16 days. Just before delivery, the expectant mother will become restless and may discharge a small amount of blood from her vulva. Do not handle or disturb the expectant mother at this time.