Home Economics Child Car Seats Are Contraceptives

Child Car Seats Are Contraceptives



When we first heard about this paper – about 15 minutes ago from loyal reader Arthur The Cat – we thought this would be about how dealing with car seats means that one never does get around to the activity necessary to have another child. Mashed thumbs leading to reduce amourosity perhaps.

No, this is actually good economic research. It’s a look at the costs of a certain decision, the incentives faced by people thinking of having another child. And the insistence upon car seats has reduced the incidence of miniature human life.

We can even say that the bureaucratic insistence upon car seats has led to more lives not being started than would have been ended by not having the bureaucratic insistence upon car seats.

Since 1977, U.S. states have passed laws steadily raising the age for which a child must ride in a car safety seat. These laws significantly raise the cost of having a third child, as many regular-sized cars cannot fit three child seats in the back. Using census data and state-year variation in laws, we estimate that when women have two children of ages requiring mandated car seats, they have a lower annual probability of giving birth by 0.73 percentage points. Consistent with a causal channel, this effect is limited to third child births, is concentrated in households with access to a car, and is larger when a male is present (when both front seats are likely to be occupied). We estimate that these laws prevented only 57 car crash fatalities of children nationwide in 2017. Simultaneously, they led to a permanent reduction of approximately 8,000 births in the same year, and 145,000 fewer births since 1980, with 90% of this decline being since 2000.

You can’t get three child car seats into a standard car assuming that there are also going to be two adults in there. There’s an expense to moving up to the next size of car that can take three such child car seats. That expense, that cost, is the disincentive which leads to the 8,000 fewer births per year. For, yes, in this modern world women are in charge of their fertility.

Child car seats might not kill children, or at least not often, but the use of child car seats stops the killing of 57 children a year at the price of 8,000 births not happening a year. On nett therefore child car seats lead to a 7,943 children deficiency each and every year.

Of course, if we really wanted to reduce pregnancy and childbirth then we’d use child car seats in a different manner. There’s at least one claim out there of 750,000 teen pregnancies a year. We suggest that more than 8,000 of them would be prevented by all cars used for drive in movies and other courting activity having a child seat mounted in the back. Even if the reminder to be careful didn’t always work the base gymnastics required would slice more than 1% off the number.



  1. JGH,
    Not true of all parenting; you have the first that way, sure. But #2 and above, I think (as a parent) you do consider the effects.

    Regarding the effect in the paper, moving from having 3 to 4 kids in my case (all “planned” in the sense that they were wanted and not an “accident”), we had significant additional costs. Had to move to a large people mover with 7 seats to accommodate the brood. Wouldn’t have wanted it otherwise because the payoff (utility in econ jargon) far outweighed the cost/bother involved.

    So fundamentally disagree with your premise.


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expunct (ɪkˈspʌŋkt)
VERB (transitive)
1. to delete or erase; blot out; obliterate
2. to wipe out or destroy

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