It won't do your baby much good if you're a hood ornament so no matter where you are sitting in the car, buckle up. Any damage that a seat belt could cause pales in comparison to the potential damage if you don't.
Wear it under your belly and snug along your hip bones along with the shoulder belt (don't tuck it under your arm).
Air bags are also safe and should be used with (not instead of) seat belts.
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