How much baggage is allowed for an infant in international flight.?

Answer 1

It is dependant on whether a ticket was purchased for the infant or not.

If a ticket wasn't purchased for the infant, then the infant isn't allowed any luggage.

If a ticket had to be purchased for the infant, then normal baggage limits would apply.

Answer 2

If you are travelling with an infant or child, you are allowed to check in a stroller and or car seat without penalty. Otherwise if the infant has no seat, you are not allowed extra baggage. Most airlines make exceptions for parent's with children and thus you shold be able to carry on a diaper bag onboard. Call the airline as each airline has different rules and regulations.