Car seats are categorised according to groups or stages. The two systems are based on the child's weight and development. For infants, 'Group 0' or 'Group 0+' rear-facing car seats are needed. These are also referred to as 'infant carriers'. These car seats are attached via the seatbelt and the infant is in a reclining or semi-reclining position while travelling. It is easy to carry these kinds of car seats around with the infant secured inside it. This allows for a sleeping child to be carried inside without waking up. They are also useful as rockers when inside the home. The infant carrier seats have handles built-in, which makes carrying them easier. This only becomes a problem when the infant picks up weight and the seat becomes heavy and bulky to carry. Some of these seats form part of a modular baby transport system and can be attached to a pram or cot base.
'Group 0' car seats very often have special padded attachments which keep your child's head in position during driving and carrying, to make sure that their neck is not damaged.
When an infant weighs more than around 13 kilos (29 pounds), or the top of their head protrudes over the top of the car seat, they need to a stage two, or group one forward-facing car seat. There are combination car seats that can be used as rear-facing for infants, then forward facing when they are older and heavier. Some newer car seats use a system whereby the car seat is secured sideways on the back seat and the child lies down, secured by a single broad strap.
Car seats should always fit properly and be correctly installed. Rear-facing car seats should not be used on front seats with installed airbags. Avoid buying second-hand car seats or inferior quality seat products.