Animals with shorter gestation periods have multiple babies, like your typical house mouse, a breeding machine that’s pregnant for just 19 days—yielding between 12 to 20 babies every two months.

Syrian hamsters typically have the shortest gestation period of just 16 days. For Chinese and Russian Dwarf hamsters, on the other hand, pregnancy could last for about 18 to 21 days.

Long gestational periods in animals in usually linked to brain complexity and animal size. advertisement. ... In these cases, gestation keeps the baby in the womb longer as an adaptation.