I'm the novice here but I can tell you my own recent experiences. We adopted Pookie on 8-29-2006 two days later we wanted to make sure she was healthy so we took her to a vet that was said to be the best guinea pig vet around. He checked Pookie out said no pregnancy and weighed her in at 1.lb 4 oz. . A week later Pookie was scratching so we returned to the vet Pookie had gained 3 ounces, still no to pregnancy. A week later we weighed Pookie at home, she weighed 1.lb 13 ounces. We home school so Pookie was petted, picked up, cuddled many times throughout the day and night. We never felt babies or saw anything on the tummy. Pookie did get big hips the third week we had her and she was starting to drag her tummy in the playpen and by the 4th week I was afraid we were feeding her too much. On Sept.26th I fed Pookie at 7:AM as usual. She was making big noise for food and she ate every bite. She looked ok but she was more reclining while she ate instead of sitting on her rump. At 10:30 when we checked her water Pookie was in the igloo licking off two pups. We have a small house and Pookie never made a sound to let us know anything was going on. We weren't expecting pregnancy. The biggest difference in Pookie was how broad her hips got and her tits got bigger too. The day before Pookie gave birth she was quieter then usual and I was afraid she was getting sick but I found no evidence of this when I checked her out. I think every piggie like every woman is going to be a bit different in pregnancy. I would take your girl to a good vet who really knows about guinea pigs. Get a referral from someone besides the people who work for the vet. Our babies are two weeks old today but we would have done so many things differently if we had known she was pregnant.