My guinea pig is approx yr old and pregnant this is her 2nd litter should i be worried?

Seeing she has already had a litter, she should be okay to deliver the second litter. Keep her intake of veges high, especially those high in vitamin C and calcium. Cos lettuce, capsicum, broccoli, parsley and alfalfa hay are all great things to feed pregnant guinea pigs, and it will help the babies grow strong. Be careful when you pick her up so you don't injure the babies. You can get her to walk onto a towel then pick the towel up; I've read that's the best way to pick up pregnant piggies. That way you're supporting more of their body.