Infant and lap child fares and fees on international travel, including award & upgrades

On AA there is no charge for a lap child on domestic flights. In most instances for international travel the cost will be 10% of the adult fare in the cabin of travel (be aware in some instances / on some other airlines, it can be 25% of the cost of an adult ticket). From aa.com:

Are you traveling with an infant?

Passengers are considered infants if aged over 2 days and less than 2 years at the beginning of their journey. To travel with an infant, you must be an adult passenger aged 16 or older. Adults can travel with up to two infants and in these circumstances, can purchase an additional seat at a child fare.

Although infants can travel as early as 2 days after birth, you'll need to provide a medical certificate for infants traveling within 7 days after birth. Please contact Reservations for more information.

On U.S. domestic flights:

Infants not occupying a seat travel for free. If you prefer to book a seat for your infant, a child fare will apply.

You must call AA on the phone to add a lap infant to an existing reservation. The lap infant will NOT appear in the online reservation and receipt.

Travelers with a lap infant may check in online, for domestic flights only, and the boarding pass will be annotated with the words "WITH INFANT" immediately after the traveler's name.

On international flights:

Infants not occupying a seat benefit from a 90% discount on most adult fares

If your infant turns 2 during your trip, we'll provide you with a complimentary seat on the return flight. If the return journey is not on American Airlines, please contact the other airline to check if a seat must be purchased. (Infants and children must provide passports with any required visas; all children not traveling with both parents may be required to have a Letter of Consent signed by both parents.)

You must call AA on the phone to add a lap infant to an existing reservation, and will need to pay the fare at that time. The lab infant and fare WILL appear in the online reservation and receipt.

Travelers with a lap infant may NOT check in online for international flights and must check in at the airport.

NOTE: AA will not generally block a complimentary spare seat to be used by an infant or lap child. If seats are available at the airport, it might be possible to be assigned seating to include an adjacent empty seat if the flight will depart with sufficient empty seats.

Bassinets: These are portable, not bulkhead fastened, floor bassinet boxes. Not all aircraft may offer these, and generally are restricted to bulkhead seats.

See the bassinet thread here."]here.

See more here on aa.com.

For AA policies on required documentation for children, see here.

and

This thread regarding the use - and prohibition, on some aircraft - child safety seats.

For older threads on this topic, see: