Hearing loss in a baby is usually linked to genetics or certain infections during pregnancy, like rubella or cytomegalovirus, rather than being caused by the birth process itself. There isn't a single percentage that applies generally, since it depends on the specific cause in that family.
Next Steps
If there's a family history of hearing loss, a preconception consult can help assess inherited risk and whether any screening is worth arranging.
Health Tips
Please consult an ENT specialist for the hearing-aid timing and earphone/loud-music questions, since those aren't pregnancy-related causes.