Guinea pigs generally have between one and four babies, or pups, in each litter, according to Guinea Lynx. However, on rare occasions, a mother guinea pig, also called a sow, can have seven or more pups in a litter.
The gestation period for guinea pigs lasts between 59 and 73 days. Sows become sexually mature and able to breed at around four weeks old, and they are capable of getting pregnant again just hours after giving birth. Because of this, it is recommended that all male guinea pigs, also called boars, be removed from a cage containing a new guinea pig mother and her litter.