Car seat that conforms to official regulations
Did you reserve a seat for your infant? For his or her comfort, you can bring a car seat as long as:
it is authorized for standard automobile use (a non-standard car seat may be refused by personnel upon check-in or boarding),
it does not exceed 44 cm / 17.3 in. or 42 cm / 16.5 in. in width if your seat is located in the first row of the Economy cabin,
you make sure to install the seat on board as indicated by the manufacturer's instructions (front or back facing the seatback),
it can be held in place by a seat belt.