According to the American Academy of Pediatrics, you should not introduce juice into your baby's diet until they are at least 12 months old.
The Food and Drug Administration (FDA) recommends sticking to 100% fruit juice and avoiding unpasteurized juice products, including homemade and freshly squeezed juices, for infants, children, and adolescents.
This is because unpasteurized juices may contain bacteria that pasteurization would have killed.
If you're purchasing a store-bought juice, check the label carefully to determine whether it's pasteurized —the FDA requires unpasteurized products to have a warning label.
Additionally, note that while some types of pasteurized juices are shelf-stable, others may need to be kept refrigerated or frozen to prevent foodborne illness. The bottle will include information on whether refrigeration is required.