The animal with the shortest pregnancy is the opossum.
The gestation period for a Virginia opossum is only 12 to 13 days, making it one of the shortest gestation periods among mammals.
Other animals with short gestation periods include:
- Gerbils: 16-19 days
- Hamsters: 15-18 days
- Guinea pigs: 59-72 days
- Rabbits: 28-35 days
It is important to note that gestation periods can vary slightly depending on factors such as species, individual health, and environmental conditions.