A female guinea pig should be bred when she is about four or five months old and weighs about 500 grams. The female guinea pig will require more food during her pregnancy. Give the mother extra food pellets, fresh fruits and vegetables, and double her vitamin C intake. This diet will keep the mother healthy from disease. Keep the mother's environment as constant as possible.
Stress caused by new surroundings can cause fatal birth complications.
Do not interfere with the birth of the cavies. However, if the birth takes much longer than a half-hour you should contact a veterinarian. It's important to interact with the cavies soon after their birth. This early human interaction will make them better acclimatized to humans in the future. Be sure that the cavies are fully weaned before you give them away.