There is no published evidence which sets out how long babies should be kept in a car seat when travelling. However, infant healthcare professionals, safety experts and most car manufacturers recommend that babies should not be in a car seat for longer than 2 hours at a time and they should be taken out frequently.

For a 12-month-old child, pediatricians and car seat safety experts generally recommend following the "two-hour rule." This guideline suggests that infants and young toddlers should not remain in a car seat for more than two hours in any 24-hour period without a significant break. The primary concern is "postural asphyxiation," where a young child’s relatively heavy head can fall forward during sleep, potentially restricting their airway, especially if the seat is not at a perfect recline. Additionally, being strapped in a fixed position for extended periods can put unnecessary strain on their developing spine and limit blood flow to the back of the legs. On long road trips, it is essential to plan "active" stops every 90 to 120 minutes. During these breaks, you should take the child completely out of the seat, allow them to stretch, crawl, or move around on a blanket, and perform a diaper change or feeding. This not only ensures their physical safety and comfort but also helps prevent the irritability and restlessness that often lead to "travel fatigue" in both the child and the parents.