Car seat laws have the unintended consequence of large reductions in birth rates, due to the outsized cost of having a third child in a car seat. Nickerson and Solomon estimate that these laws are currently preventing approximately 8,000 annual births, around 141 times greater than plausible estimates of the number of lives saved in car crashes.


Effect of Car Seat Laws on Fertility

Using federal data on fatal car crashes dating back to 1975, Nickerson and Solomon find that the impact of car seat laws on deaths of children below age eight is miniscule. They estimate that existing car seat mandates prevented 57 fatalities nationwide in 2017, with the most favorable estimates being 140 fatalities prevented.

Effect of Car Seat Laws on Child Fatalities

- Nickerson and Solomon obtain state car seat laws using Lexis Nexis StateCapital and NexisUni.
- Data on car crashes come from the Fatality Analysis Reporting System, from 1975 to 2018. 
- Data on birth rates come from a compilation of assorted U.S. Census Bureau data
products, aggregated and standardized by IPUMS USA, a service of the Minnesota Population Center.

Data Selection

Nickerson and Solomon use a panel regression setting where the main dependent variable is a dummy variable equal to one if the woman in question gave birth that year. Their main independent variable of interest is Two Children, Both Bound. This takes a value of one if the woman already has exactly two children whose age and state-year mandate requires they use child safety seats. 

Methodology

Since 1977, U.S. states have passed laws mandating that children be restrained in child safety seats. Initially these laws typically applied to children ages one to three, but since the mid-1990s they have seen a huge ratcheting upwards. The median age for seat belts in U.S. states is now eight, despite multiple studies showing that child car seats are generally no more effective than seat belts in preventing death or serious injury for children above age two.

History of Car Seat Laws (U.S.)

Nickerson, Jordan and Solomon, David H., Car Seats as Contraception (July 31, 2020). Available at SSRN: https://ssrn.com/abstract=3665046 or http://dx.doi.org/10.2139/ssrn.3665046

University of Minnesota - Twin Cities

Health Economics References

What Is Health Economics? Johns Hopkins Bloomberg School of Public Health. https://www.jhsph.edu/departments/international-health/global-health-masters-degrees/master-of-health-science-in-global-health-economics/what-is-health-economics.html.

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