It’s not uncommon for newborns to turn their heads to one side of the car seat. This is perfectly safe for most children. The dangerous position is when the newborn slumps their head forward in a chin-to-chest position. This pinches the airway and restricts their breathing, which can be deadly. To prevent this, follow the installation and harnessing instructions in your car seat manual exactly. Of particular importance is the recline angle of the car seat.
If you would like to provide additional support around your baby’s head, you can use the infant insert that comes with your car seat, or check with the car seat manufacturer to see if they sell an insert that is compatible with your car seat. Never purchase infant inserts that are not approved by the manufacturer. These are not crash tested with your particular car seat, so there is no way to know what effect they could have on your child’s safety in a crash. It is possible that these after-market inserts could allow for too much slack in the straps and are likely not flame-resistant according to federal standards. If no approved insert is available, you might consider placing clean, rolled-up receiving blankets vertically by each shoulder.