Booster seat dilemma

Little T has finally grown out of his infant car seat. C and I debated whether to graduate Special K to a booster seat. She weighs just over 30lb and is about 38 inches tall, so she just about qualifies for the Britax Parkway. It costs $89 while a car seat costs $230. Special K has more freedom to move around in a booster seat. However a booster seat is easier to install wrong and can be less safe.

In the end we decided to buy the booster seat and use it as the spare car seat. Our nanny uses this seat to take Special K to gym and for occasional other trips. Right now our spare car seat is a Britax Roundabout. We'll put Little T in the Roundabout. By the time Little T grows out of the Roundabout, we should be comfortable having Special K in a booster seat full-time.

It amazes me how stressed out I got making this decision. I'm the parent banned from a group of mothers for letting Special K eat sand. Yet I got scared when I read sites that "Children should be get in harness restraints as long as possible." and "children under 4 should not ride in booster seats." Also two years ago our car was rear-ended by two cars in a car pileup. Special K was just under 1. WS and I both had back injuries that required treatment while Special K escaped unharmed.