well my baby is four months now and she wore the Huggies new born diapers until two or three months; its all depending on the size and weight of your baby :)
Are you sure they are not a size 1? Huggies Newborn only fit up to 10 pounds and cannot be work every long unless the baby is tiny. A size 1 is what goes up to 14 pounds in Huggies.
Luvs size 1 fit babies 8 - 14 pounds, but there isn't a diaper that only has a weight range of 4 pounds, as you stated, to fit 8 to 12 pounds.
So are they a size 1 or a size newborn? I would definitely be interested since I use tons of diapers per day, but only if they are the size I use.