Spirit Airlines Infant Policy: Spirit Airlines requires infants traveling on the lap of an adult to be included in the reservation at the time of booking. During the booking process, passengers need to indicate the number of infants traveling to ensure appropriate seating arrangements. Additionally, parents or guardians must carry the necessary documentation for the infant, such as a birth certificate or passport, as per the airline's guidelines. By providing clear instructions and accommodating infant travelers, Spirit Airlines aims to make the journey stress-free for families.