Three car seats?

post by jefftk (jkaufman) · 2020-10-01T14:30:06.216Z · LW · GW · 9 comments

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9 comments

I recently was linked to Car Seats as Contraception, which argues that car seat laws have led to parents choosing to have fewer children because "physical limitations of many cars precludes the use of three car seats in the back seat." Now, this is a correlational study, so I'm skeptical that this is a real effect, but the premise here is also strange. If the only way to have three children in your car was to buy a larger car, I see why that could be a major issue for a lot of people. On the other hand, buying a narrow car seat is pretty straightforward, and three narrow seats fit across the back of almost anything.

We have several Cosco seats that are 17" wide. They are one of the cheapest seats out there ($50), and they fit three-across in almost anything. Manufacturers publish "rear shoulder room" measurements for their cars, so roughly we're talking about cars with at least 51". Alternatively, if you're willing to spend 4x as much ($200, still small compared to the cost of a car or of raising a child) there are 16" seats which would only need 48" across the back. Small cars I checked:

Of these, I think we've put our seats three-across in both the Toyota Corolla and Honda Fit, the two smallest on the list, without issue. It's more annoying than just putting in two, but if you own your car (unlike us) you can leave them installed. There are tons of blog posts on this. This mild hassle doesn't seem like it could be large enough to cause a substantial shift in whether or when people choose to have a third child?

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comment by Gunnar_Zarncke · 2020-10-01T21:53:50.336Z · LW(p) · GW(p)

For what it is worth: We have cycled thru used cars pretty quickly. I think we had six cars from before the first was born to after the fourth (and last) was born. Since then the car has been the same (a used Renault Espace 7 seats, all back seats removable).  

comment by moridinamael · 2020-10-01T16:21:12.253Z · LW(p) · GW(p)

It qualifies as a trivial inconvenience. We had to essentially buy three new car seats when we had our third, because the two that we were using for the first two kids took up too much space, and needed to be replaced with thinner versions.

It does seem like having four children would pose more serious difficulties, since you can no longer fit four young children in a sedan no matter what you do.

Replies from: jkaufman
↑ comment by jefftk (jkaufman) · 2020-10-01T16:52:46.625Z · LW(p) · GW(p)

you can no longer fit four young children in a sedan no matter what you do

https://www.multimac.com/p/multimac_1320_4_seater

Replies from: moridinamael
↑ comment by moridinamael · 2020-10-01T20:23:46.628Z · LW(p) · GW(p)

https://www.multimac.com/p/multimac_1320_4_seater

£1599.00 =)

It's pretty cool, but hardly a slam-dunk rejoinder if the whole issue in question is whether having a 3rd of 4th child is discontinuously costly due to sedan width.

Personally, I just ended up buying a minivan.

Replies from: jkaufman
↑ comment by jefftk (jkaufman) · 2020-10-01T21:52:02.835Z · LW(p) · GW(p)

No, I agree, it's only useful in pretty niche situations. Mostly I was excited to see a counterexample to as strong a claim as "no matter what you do"

comment by Viliam · 2020-10-01T15:57:12.506Z · LW(p) · GW(p)

When I asked people with 3+ kids what was the extra difficulty of having more than 2 kids, I remember them mentioning the problem of driving the whole family in one car.

But I would still assume that when people decide whether to have the third child, other things are more important. And as you write, the problem can be fixed by choosing the right type of car.

I haven't read the study, so I wonder whether it properly controls for wealth. Poor families have more children on average, and are also less likely to own a car. Similarly, absence of a father may have an impact on family beyond leaving a front seat empty.

Replies from: jkaufman
↑ comment by jefftk (jkaufman) · 2020-10-01T16:53:39.533Z · LW(p) · GW(p)

They did at least try to control for wealth: "We find that the estimated effects are driven entirely by households with access to a car, consistent with car usage mattering directly. The effect is also concentrated in households where there is an adult male in the household, increasing the likelihood that both front seats are occupied by adults. Somewhat surprisingly, the effects are larger among households with higher income levels. This suggests that the pressures leading to reduced birthrates may not be entirely financial, or that these groups bear a greater burden through higher compliance rates."

comment by cramitin · 2020-10-02T06:00:24.324Z · LW(p) · GW(p)

Do the 17" car seats fit kids up to 4'9" tall and 80 pounds?

Do three 17" seats fit in any car that claims to have 51" of shoulder room? For example, would all three seats line up with the LATCH anchors, or could the outer seats be too far to the outsides?

What about rear hip room? That's less than rear shoulder room, often less than 51" or 48". 

Replies from: jkaufman
↑ comment by jefftk (jkaufman) · 2020-10-02T11:59:29.874Z · LW(p) · GW(p)

The 17-in seat I linked is for kids who aren't ready for a booster seat yet. Once they outgrow the car seat they have many narrow options. For example, this booster seat is 14.5": https://www.amazon.com/dp/B07RB2KRCS

Using the anchors requires the seat to go in a very specific location, which is often not what you want. You can use the seat belt instead. If you want to use a car seat with a heavier child, you're generally required to use the seat belt anyway because it's stronger.

In my experience the limiting factor is not the space at the back of the seat, because all of the seats are smaller there. The Honda Fit, for example, only has 45-in of hip room, but does fit our three 17-in car seats.