Rodent and Small Pet Gestation Periods
Small pets have the shortest pregnancies of any mammals kept at home. A hamster is pregnant for about 16 days, a mouse 20, a rat 22, a gerbil 25, a ferret 42, a guinea pig 68 and a chinchilla 111. A missed mating can therefore become a litter in under three weeks.
| Species | Average days | Range | Months | Young |
|---|---|---|---|---|
| Hamster | 16 | 15–18 | 0.5 months | 6-8 pups |
| Mouse | 20 | 19–21 | 0.7 months | 5-8 pups |
| Rat | 22 | 21–23 | 0.7 months | 6-12 pups |
| Gerbil | 25 | 24–26 | 0.8 months | 4-8 pups |
| Ferret | 42 | 38–44 | 1.4 months | 6-8 kits |
| Guinea pig | 68 | 59–72 | 2.2 months | 2-4 pups |
| Chinchilla | 111 | 105–118 | 3.6 months | 1-3 kits |
What these animals have in common
Most small rodents follow the same strategy: many young, born early in development, raised quickly in a nest. Hamsters, mice, rats and gerbils are born hairless, blind and entirely dependent, and the mother compensates with rich milk and a fast growth curve rather than a long pregnancy. Guinea pigs and chinchillas are the exceptions, carrying their young far longer and giving birth to fully furred, mobile pups that can eat solid food within days. Two practical rules follow. First, separate the male before birth, because many rodents come into heat again within hours of giving birth and will conceive immediately. Second, leave the nest alone for the first week: disturbance, strong smells and handling can cause a mother to abandon or cannibalise a litter. Provide deep bedding, plenty of nesting material, constant food and water, and keep the cage in a quiet, stable location.
Species pages in this group
Frequently asked questions
Figures are averages from published data. Individual animals vary, and results are for planning rather than veterinary advice.