With a five-week old baby, that means that you should:
- Read the car seat instructions carefully to make sure that you have installed and are using it correctly
- Use either an infant-only car seat (which has a detachable carrier) or a rear-facing convertible car seat
- Place your baby rear-facing in the back seat of your car and never place your baby in the front seat of a car with a passenger side air bag
- Attach the LATCH straps or seat belt to the car seat tightly
- Make sure that the car seat is reclined at the proper angle, which may require that you place some foam padding under the car seat's base
- Make sure the harness straps are snug when you strap your baby into the car seat and that the plastic harness clip is at her armpit level and not too low
Sources:
American Academy of Pediatrics. Car Safety Seats: A Guide for Families 2011.

