@david3r1 Extended rearfacing is generally accepted as the safest practice. It is the recommendation of the AAP. It is certainly not harmful to children and may confer some additional safety benefits. We choose to rear face longer term even though cars are pretty safe on the whole because the costs are low (discomfort) but the potential benefit is high (potential additional protection in a crash).
However, in the interest of science, it’s worth noting that there is honestly
not a suite of evidence behind this recommendation in comparison to other safety recommendations that are strongly endorsed - the case for extended rear facing is primarily based on:
- A paper that came out in 2007 (Henary et al) that found statistically significant evidence that children ages 0-23months had fewer injuries rearfacing. This paper was called into question and then retracted by the journal in 2016 after independent statisticians could not replicate the findings.
- A paper in BMJ found children rear facing had lower injury rates (but the sample size was too small to find statistical significance). Similarly, in 2017, a paper found lower rates of accidents in kids ages 0 and 1 but not a large enough sample to reach statistics significance.
- Swedish data (based on a mix of Volvo safety testing and government and Volvo-specific accident data) which found that crash test dummies benefited from extended rear facing and rearfacing seats outperformed belt positioning boosters when it came to reducing injuries (forward facing car seats are uncommon in Sweden). No other country/market has published data on this but Sweden is generally recognized as a country at the forefront of car seat safety.
- Logic. Based on what we know about how bones (specifically your spine) fuses, about the relative prevalence of accidents between frontal, rear and side impact and the relatively low “cost” (time, discomfort) of rearfacing, we err on the side of caution and recommend extended rearfacing.
ETA: to be intellectually honest, there
is also evidence that car seats don’t confer death-reduction benefits after age 2. Stephen Levitt of Freakonomics fame published in 2005 a
study that looked at NHTSA data and found no reduction in fatalities due to car seats compared to seat belts alone. That study was both
replicated by different researchers and its conclusions were affirmed after looking at 6 additional years of data in 2014.
These studies looked primarily at fatalities, not all injuries (the original piece did have some injury-related conclusions) and other studies have found reductions in injuries by
up to 80%, however, these studies generally haven’t articulated an additional benefit specifically due to rear facing position.
For me personally, the case above on rear facing is credible enough that it’s worth it to stay in a car seat and stay rearfacing.