Properly Secure Your Baby in an Infant Car Seat

A 2016 study reported that at least 90% of all seats are not used properly—half of all seats had at least five different errors. Lots of parents don't read the car seat instructions or look at the labels, so it's easy to make mistakes. These tips are a starting point to help you buckle your baby safely in an infant car seat.

Not all infant car seats are the same, so some features may look different on your own seat. Read through the instruction manual before you use it, and familiarize yourself with the seat's features and requirements.


Make Sure the Car Seat Fits Your Baby

Not every baby will fit perfectly in every infant car seat. You can find the height and weight requirements for your car seat on the required labels on the side.​

If your baby is very small, they may not meet the minimum weight requirement.


Set Up the Harness Straps

All infant car seats have more than one harness height position. Check the instructions to learn how to adjust the height of the shoulder straps. Some require you to rethread the shoulder straps from one slot to the next, while others have a no-rethread harness where the shoulder straps are connected to a plate (often a head rest) that can move up and down. As the plate moves up, the shoulder straps go up; as the plate goes down, the shoulder straps go down.

In a rear-facing car seat, the harness straps should be slightly between or below baby's shoulders. To set up a car seat for a baby who hasn't arrived yet, you can usually choose the lowest set of harness slots. Once your baby is born, you'll need to sit the baby in the car seat and check to see which harness slot works best. Choose the slots that are closest to baby's shoulders ​without being above the shoulders.

If you're afraid you'll get the harness wrong when you un-thread the straps to reposition them, take a picture of the car seat, front and back, before you take anything apart. That way you can refer back to the photos if you're not sure how it should look after adjusting.


Check the Buckle Position

Some infant car seats only have one crotch strap and buckle position. The crotch strap is the portion of the harness that comes up between baby's legs. The buckle itself is on the end of the crotch strap.

Many car seats have multiple positions for the crotch buckle. The various buckle positions allow you to move the crotch strap in close to a tiny newborn, and then to move it out later to accommodate a larger infant. Some infant car seats also have multiple height settings for the crotch buckle, allowing it to be lowered for the smallest babies so there's room for all the buckle hardware to fit over their tiny belly.

The crotch strap should be as close as possible to the baby's body. The farther away it is, the more the baby can slouch into the gap. Slouching is dangerous because as the baby slouches, their chin can drop to their chest, which can cause them to have difficulty breathing.

Some buckle positions are changed by taking the strap out of the slot and moving it to a new one. Some have a sliding mechanism or push-button system to adjust the buckle position.

Check your car seat instruction manual for specifics on how to adjust it, and when you should move to the next position.


Loosen the Car Seat Harness Straps

Before you place your baby in the car seat, loosen the harness straps. The most common way to loosen the harness is via a lever or button between baby's feet. Sometimes the release mechanism is hidden beneath a flap.​

Loosening straps always requires two hands (this is so kids can't figure out how to do it by themselves!). One hand will be pushing down on a tab or lifting up on a lever, while the other hand takes the shoulder straps and pulls them away from the child's body.

The easiest way to find the loosening mechanism is:

  • Find the tail that hangs off the edge of the car seat (near the baby's feet).
  • Follow the tail to where it emerges from the car seat. There will be a tab to push or a lever to lift right where the strap emerges from the car seat.
  • While pushing down or lifting up (as appropriate for your child's car seat) use your other hand to pull the shoulder straps forward to loosen them.

If your car seat doesn't have a front adjuster, you'll need to check the instruction manual to find out where you loosen and tighten the harness. Some budget infant car seats have a rear-adjust system.


Place Your Baby in the Car Seat

Move the harness straps to the side and pull the crotch strap and buckle forward before sitting your baby in the car seat. Baby's bottom and back should be against the seat. Hold the baby's thighs and wiggle the baby all the way back and down in the seat (the baby should not be slouching at all).


Buckle Your Baby Into the Car Seat

Bring the harness straps around baby's shoulders and make sure the webbing doesn't have any twists in it. You will need to smooth out the harness webbing each time you buckle your baby in because twisted straps are not as effective when it comes to protecting your baby in a crash. (See a video explaining how to untwist straps.)

Place the buckle tongues into the buckle housing until they click. Some buckle tongues must be puzzled together in a specific way before you can snap them into the bottom piece of the buckle. Your car seat instruction manual will show you exactly how to work the buckle.


Buckle the Harness Retainer Clip

The harness retainer clip is often called the chest clip. Simply snap together to secure. For now, it should be near the baby's belly.


Tighten the Car Seat Harness

Just because the buckles are fastened doesn't mean you're done! Tightening the car seat harness is a very important step in making sure your baby is buckled up properly. You need to do it every time you buckle your baby in. If you leave the straps set, they will be too loose.

Start by sliding the chest clip down to the baby's belly. Keep it near the belly while tightening the straps. It only gets moved up to armpit level after the straps are properly snug.

Position your body at the head of the car seat (you will need this leverage) and pull up at the shoulder straps, while keeping the chest clip low. This gathers the slack up to the shoulders. Next, remove the slack by pulling the tail.

Most car seats have a tail of webbing that comes out of the seat between baby's feet. To get the straps snug, pull firmly on that webbing tail. This video demonstrates the whole process.

When the harness is tight enough, you shouldn't be able to pinch any excess webbing on the harness straps. The harness should be snug against the baby, with no gaps.

If your car seat doesn't have a front adjuster, check the instructions to see how to tighten the harness. Some car seats have buckles on the back of the car seat or knobs on the side that tighten the harness.

For newborns, you may find that there's still a little bit of space between the baby and the crotch strap. If your baby slouches into this gap, you can prevent this by placing a tightly rolled ​washcloth between the baby's diaper and the crotch strap after the baby is buckled snug in the straps. If there's a lot of space, double check that there isn't a closer buckle position that you missed in a previous step.

The rolled washcloth trick is widely accepted by car seat safety experts as an appropriate solution to a temporary problem. You should still read through the instructions that came with your car seat, or call the manufacturer's customer service number, to make sure the practice is OK. You might also find that your car seat has an extra infant insert or some other way to help tiny babies fit properly.

Once you have the harness straps adjusted, slide the chest clip into position at baby's armpit level. With a newborn, it can be hard to get the chest clip into position when you don't have much space between the buckle and shoulder pads. It's important to make sure you get the clip up there, though, because it holds the harness straps in the right position to work best in the event of a crash.

Shoulder Strap Covers

Shoulder strap covers are almost always an optional part of a car seat. You may want to remove them, for several reasons:

  • Kids typically find them uncomfortable, as they add extra pressure into the side of the child's neck (simply pull the child's shirt up in between the strap and the neck to keep the strap from rubbing the child's skin, if necessary) .
  • Covers typically make the straps twist (and twisted straps aren't safe)
  • They are not a safety feature, unless the manual specifically states that they are required).
  • They are often too long for newborns, and make it impossible to get the straps properly snug and the chest clip at armpit level.

Keep Baby Warm Safely

New parents want to shield their babies from rain, cold, and other unpleasant weather. It's OK to add a blanket to cover your baby, but you must put the blanket over the top of the harness. Never place blankets, thick clothing, or winter coats underneath the car seat harness. Since babies and children should not wear bulky clothes under car seat straps, they will often need more than a thin blanket on top to stay warm. In cold weather, dress your baby in several thin, close-fitting layers.

Thick padding and blankets under the harness don't allow the harness to fit tight enough to be safe.

A blanket over the top of the buckled harness, then tucked in around your baby, is usually enough warmth for most situations. You might also consider a winter car seat cover if you need to be out and about with baby in cold weather.​ Choose one that goes on top of the car seat—never the type where there is a layer of fabric under the baby's body.

Don't add any other accessories to your baby's car seat unless they're approved by the manufacturer or they came with the car seat.

6 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Hoffman BD, Gallardo AR, Carlson KF. Unsafe from the start: Serious misuse of car safety seats at newborn discharge. J Pediatr. 2016;171:48-54. doi:10.1016/j.jpeds.2015.11.047

  2. National Highway Transportation Safety Agency. Find the right car seat.

  3. The Car Seat Lady. Rear-facing only car seats.

  4. National Highway Transportation Safety Agency. Fitting your child correctly into the seat.

  5. Children’s Hospital of Philadelphia. Car seat safety: Newborn to 2 years.

  6. American Academy of Pediatrics. Rear-facing car seats for infants and toddlers.

By Heather Corley
Heather Wootton Corley is a mother, freelance writer and certified Child Passenger Safety Technician-Instructor.