General Information about Breeding Roborovski's

Breeding two Roborovski's is not difficult, but even then, it should only be considered if you are absolutely sure you know what to do and have looked into it.
Female Roborovski's enter the oestrus cycle every 4 days. They remain fertile for a period of 12 hours in which mating can occur. That is, if the male manages to catch the female which can prove to be quite a challenge for him.
The female can produce a litter every 4 weeks or so but seem to limit themselves to about 3-5 litters in succession.
It is believed that Roborovski's are seasonal  breeders meaning they usually mate in the spring or early summer; however this may be related to the increase in day length and temperature. Artificial lighting and heating could have the effect of prolongating the mating season, maybe even stretching it to the whole year round.
But even then they may limit themselves form producing too many litters in succession (as explained above). Some breeders report that Roborovski hamsters do not seem to breed until the spring following the year the female was born. 

Is my Robo pregnant?

Female hamsters go through a cycle every three or four days and will regularly produce a discharge as part of this cycle, so it does not mean she is pregnant.

There are no sure signs that the female is pregnant - all hamsters hoard food and can make more than one nest - the only way to know for sure is when she actually has the babies!  Sometimes they will get a little fatter and sho but this is usually only on the last day or two and only if she carrying a large litter.

Age of sexual maturity and when to start breeding

Robo's 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). The ideal age to start breeding is about 5 to 6 months of age. The female will be fully grown and matured by then and will be strong enough to produce and raise a litter. While the male usualy will remain fertile throughout his life, the female often becomes sterile after 2 years of age. Most experienced breeders say that Roborovski's do not breed succesfully until the following spring the female was born.

Length of pregnancy

The gestation period of Roborovski hamsters is usually 20-22 days but can be as many as 30 days according to some sources. (Roborovski's have the longest gestation time of any hamster)

Litter Size

The litter size is of Roborovski's is usually small, typically 4-6 pups per litter (though larger litters of up to 10 have been reported).