Lie flat car seats offer a safe and healthy environment for babies. Tests have shown that subjecting an infant to extended periods of time in a rear facing infant carrier can be detrimental to a newborn's development. This includes oxygen desaturation due to compression of the lungs, and restrictions due to the harness. Back development is also compromised due to the angle of the infant carrier.
In our opinion lie flat car seats are the preferred choice for new born babies.