Babies born to hep C positive mothers are born with antibodies to hep C. Approximately 96% of those babies will lose the mother's antibodies by the time they are 18 months old. If they still have the antibody at 18 months they are likely to have hepatitis C. The baby should be tested with a PCR or viral load test. If the antibodies are due to the mom's antibodies there will be no virus found on the PCR test. This test can be given after the baby is 2 weeks old. Doing the PCR test will alleviate a lot of worry because you will know for sure that the baby is or isn't positive. I wish you good luck.
Being positive for HCV antibodies doesn't mean that your son has an active HCV infection, has he been tested for an active infection, meaning has he had an HCV RNA by PCR test, once a person has been exposed to the virus even if they clear the virus through their own immune system, which approx 20% of all that come in to contact with HCV do, they will always test positive for the antibodies, if he has cleared the virus on his own then his risk of becoming HCV positive are the same as everyone else, it would take blood to blood contact for reinfection to take place