When I’m not carseating, I work as a physical therapist in a pediatric setting. As you can imagine, there tends to be a lot of overlap with carseats and my “real” job, but you might be surprised to hear that the most common intersection of the two has to do with babies who are born with a tight neck muscle.
Torticollis is a condition where a muscle in one side of the neck gets tight, usually because of the position of the baby in utero. Torticollis tends to cause babies to have a strong preference for rotating the neck in one direction and tilting the head in the other direction. It’s most common in first babies, twins and babies of petite mothers (all because of space constraints in utero). One of the biggest issues that results from torticollis is that babies can end up with an asymmetrically flat head, known as plagiocephaly. For some kids this is mild and it improves on its own; for others, they may require a specially made and adjusted helmet to help the head round out.
In virtually every evaluation for a baby with torticollis and plagiocephaly, parents (understandably) express concern about what, if anything, they can do in the carseat to keep their baby’s head from tilting or rotating. And sometimes they’ve already tried things- usually aftermarket inserts, sometimes wash cloths, when the secret is, you probably don’t need to add anything.
As we know, adding anything to a carseat that didn’t come with the seat (or was not expressly crash tested with the seat and approved by the carseat manufacturer), is generally not a good idea. It will void the carseat warranty, it goes against every manual (which, in most states makes it illegal) and it may potentially result in injury in a crash. So, basically what I’m saying is, even if you’re worried about your baby’s head shape, please don’t put aftermarket products in the carseat. They won’t help much and they may put your child at increased risk.
Truthfully, unless your baby spends hours, like, literal sustained hours each day in a carseat, the seat isn’t really what is causing the flatness to develop. So fear not, the carseat is just fine the way it is. I know that at times seeing baby’s head tilted or rotated in the car can be troubling. But rest assured that a tilt to the side or rotation isn’t unsafe. The only position that is worrisome is if baby’s chin tips down onto its chest, which in small infants can compromise the airway (and is probably a sign that your child’s carseat isn’t reclined enough- find a CPST in your area to have it checked out!).
If you’re worried about baby’s head falling to the side, you can try rolled up receiving blankets on either side of baby, placed after baby is buckled. I will be honest that I don’t necessarily love this set up because baby could rotate their head and spend a sustained amount of time with their face in a blanket, but it is a parental decision and if you feel strongly that something needs to be done to keep baby’s head in midline, this is your safest option.
If you want to make sure that baby rotates their head to their non-preferred side, you can definitely make that happen in the carseat. If your seat allows it, and several explicitly don’t, so consult your manual, you can hang a soft toy (like, literally made of a material and so soft you would throw it directly at your child’s head and they wouldn’t be injured) from the handle, offset towards the side you want baby to look. I had one creative parent who tied a few ribbons on the non-preferred side of the handle. They presented no risk to baby, but were bright and got baby to rotate his head that way. Other options include, if you have another backseat passenger that baby will like to look at, seat that person on baby’s non-preferred side. Or if baby is not sitting in the middle seat, and you can get a good installation and feel comfortable with baby outboard, place their seat so that they have to look towards their non-preferred side to see out the nearest window.
Most of all, any baby, but especially a baby with torticollis, will benefit from the least possible amount of awake time in any baby device that puts pressure on baby’s head like a swing, bouncy seat, cradle or carseat. Babies need a lot of floor time when they’re awake so they have room to learn to roll and sit and crawl and they especially need time on their tummy to strengthen their necks, which will help correct torticollis.
If you think your baby may have torticollis or plagiocephaly, talk to your pediatrician about it and see if a referral to a physical therapist in your area might be appropriate. And if you’re worried about carseat positioning with a baby with torticollis and/or plagiocephaly, find a CPST near you to check your set up and see if there’s anything else that can be done to keep baby safe and keep baby’s head nice and round.