Guinea pig pregnancies last from 59 to 72 days, and the main determining factor is the litter's size. Smaller litters have a longer pregnancy term than larger litters.
Female guinea pigs, or sows, have varying pregnancy terms based on the number of pups in the litter. A litter of one guinea pig has an average term of 70 days, while the term of a litter of six pups runs an average of 67 days in length. It is important to consult a veterinarian to determine litter size. Guinea pigs are known for encountering difficulty while giving birth, and it may be necessary to assist with the birthing process. After birth, pups must remain with their mother for approximately four weeks while they are weaning.