Yes, he's talking about a study that showed that car seat requirements decrease birth rates because most cars cannot fit more than two car seats in them at one

Yes, he's talking about a study that showed that car seat requirements decrease birth rates because most cars cannot fit more than two car seats in them at one time. The hypothesis is that this causes families to avoid having a third child, and the author is arguing that we should eliminate car seat requirements, or perhaps make them required only for children age two or younger. Right now in many US states, car seats are required until the age of 12.