Legal Question in Family Law in California

You can't. As long as the child is attached to the mother, insurance treats it as part of the mother and care for it is handled by the mother's insurance. Once the child is born it should automatically be covered under the mother's insurance at least if proper arrangments are made for that. If you want to transfer the child to your insurance you will have to establish paternity first, since the child is automatically legally presumed to be the husband's child until proven otherwise. You would need to check with your insurance carrier or HR department on how to transfer the child to your insurance once you establish paternity.