A 5-point harness is the webbing portion of the car seat that adjusts over baby to hold him in the seat. The five points in the name are the spots where the harness webbing attaches to the car seat. Two of the points are at each shoulder, two of the points are at baby's hips, and the final point is where the harness buckles between baby's legs.
Five-point harnesses are found on nearly all modern car seats.
There may be some infant car seats still in distribution that have a 3-point harness, but these are rare. Most often they're only found nowadays in car seat distribution programs through hospitals or other agencies, but even in the distribution programs, most car seats will have a 5-point harness now. The 3-point harness does not have attachment points at baby's hips. The chest clip is also often different, usually, a one-piece paperclip style that just slides over one harness strap to hold the straps together. The 5-point harness has a two-piece chest clip that buckles the two harness straps together at the center.
How to Adjust a Five-Point Harness
Proper adjustment of the harness is key to car seat safety. The shoulder straps must be at or below the child's shoulders when rear-facing, and at or above the child's shoulders when forward-facing. With some harness systems, you need to unthread each shoulder strap from a splitter plate behind or under the car seat, move the straps to the proper harness slot, and then replace them on the splitter plate.
Other car seats offer a convenient no-rethread harness, where you can change the harness height by pushing a button or sliding a bar up and down. Some of these systems have a limited number of height settings, while others can be moved freely up and down to be placed right at the baby's shoulders.
The harness should be smoothed before each use so it isn't tangled or twisted.
When you put the child into the car seat and then take them out again, it's easy for the harness straps to become twisted as they move under and around baby's body. Not smoothing them out can quickly lead to straps that no longer lay flat and are instead wound tightly like ropes.
The harness should be tightened so that you can't pinch any excess harness webbing. The attachment point between baby's legs may be adjustable, and if so, it should be placed according to manufacturer instructions, usually as close to the child as possible. Some newer car seats even have an adjustable hip width on the harness. Just like selecting the slot for harness height, you can also select a slot to bring the harness in closer to the baby's hips, and then move it out again as baby grows.
The Overhead Shield
Another older style of car seat is the overhead shield. Instead of a 5-point harness, this type of car seat has two harness slots at the shoulders, and a buckle between the legs, but it uses a tray that swings down over baby's head and buckles instead of the hip straps. The overhead shield car seat is no longer being produced. The 5-point harness style fits closer to the child and doesn't allow as much movement, so the safer option has prevailed.