can a Three months old baby travel by train in AC 2 tier for long distance journey. like 12 to 13 hours

A. hi dear If possible, wait until your baby is 3 months old But a baby's immune system is more developed by 3 months of age, making them less susceptible to illness. (Bonus of traveling this early: Babies still tend to sleep a lot at this age, and they're not as mobile/wiggly/restless as little ones a few months older.)