If the guinea pig's stomach continues to grow, it is likely she is pregnant, She will give birth after approximately 2 months, usually to 3 babies, During this time you need to give her lots of timothy hay (available at petsmart) and fresh vegetables because she will need the vitamin C. After birth, separate the father immediately from the mother and babies, otherwise the mother could be pregnant again right away, which is very dangerous for her. After 4 weeks, you need to separate the boys from the girls.