There are many things we do in private that we hope others never see. Installing a car seat is up there for me. Having just moved from New York City, where I rarely drove anywhere, to the country, where I rarely walk anywhere, car seats have suddenly become part of my daily life, and even though I know they may one day save my son's life, I do not get along with them. When I'm fighting to install one into my car by myself, the process invariably involves instruction manuals (for my car seat and my car), YouTube installation videos (necessary since my manuals seem to be written in Pirahã), ample cursing, and me punching the car seat. Whoever said violence is never justified clearly never owned a Britax.

Most parents will agree car seats are a pain to install; worse, the stats suggest that three out of four times, we're doing it wrong. But the angst surrounding car seats does not end with installation — pretty much everything about them is ridiculously confusing. The American Academy of Pediatrics recently changed its recommendations on when to use which types of seats, but chances are, your state law disagrees. Rumor has it that next year, the National Highway Traffic Safety Administration will tell parents to stop using the Lower Anchors and Tethers for Children system (LATCH) to secure car seats once the combined weight of your car seat and your child exceeds 65 pounds, which begs the question — do you know how much your car seat weighs? I don't even know how much my kid weighs.


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Then there is the “Freakonomics” claim that car seats are in fact useless, the Consumer Reports debacle in which the organization apparently had to recall some reviews after screwing up its safety tests, and, oh yeah, the fact that some car seats simply do not fit in some cars. But hey, guess what? Your kid should be in a car seat until she's 8 years old and don't even think about letting her ride in the front seat until she's 13. K?

First, the very basics: Why these insufferable plastic contraptions are well worth the hassle. Car seats can be life-saving, and to understand why, we have to go back to high school physics. When your car flies down the highway at 70 mph, you go this fast, too. This means you and your car have a heck of a lot of momentum, a figure that reflects speed and mass. When you come to a rapid halt in a collision, your car's momentum has to drop quickly, which requires force — a force that deforms your car, among other things. Your own momentum must drop, too; you have the choice of flying through the windshield and letting the force of hard pavement stop your momentum, or you can use a seat belt, which does the same thing but a little more amiably.

Seat belts do more than just keep you from becoming a projectile; they are also slightly elastic, so they lengthen the time over which your momentum slows (as opposed to if you'd slammed into the pavement), which ultimately reduces the total force on your body at any one time. That's good. Seat belts also ensure that this force hits two of the strongest parts of your body — your pelvis and your shoulders — and that your more delicate tissues, such as your genitals, abdomen and neck, remain unscathed (unless your car gets crushed to the point of crushing you, too). So: Seat belts are awesome.

Car seats, however, are better — which is important because car crash injuries are more dangerous to children than adults. Motor vehicle accidents are the No. 1 cause of death in children; more than one-third of kids who died in accidents in 2011 were unrestrained. “For a kid, things can come apart much more easily. When we sustain whiplash, they can break their necks,” says Ben Hoffman, a pediatrician and car seat specialist at the Oregon Health and Science University in Portland. Forward-facing car seats, which the American Academy of Pediatrics now recommends kids use from ages 2 to at least 4, have five-point harnesses. They distribute the force associated with impact across an even larger area — there are more straps coming into contact with your kid's body — which means less force being applied to any single point. According to Partners for Child Passenger Safety, a long-standing research partnership between the State Farm Insurance Company, the Children's Hospital of Philadelphia and the University of Pennsylvania, forward-facing car seats really do save lives: When these car seats are not seriously misused — i.e. when parents actually strap their kids in and attach car seats to their cars (apparently some don't even try?) — car seats of all types reduce a 2- to 6-year-old child's risk of death in a serious crash by an average of 28 percent compared with seat belts.

But it's the rear-facing seats that are the real life-savers for kids under 4. Most crashes are frontal, which means that the force applied to riders typically comes from the front. Rear-facing seats distribute the force of impact along the entirety of the backside of your child's body. Again: same force, but it's distributed across a much greater area still, which means, yes, less damage. Rear-facing seats also prevent kids' heads from flying forward as happens to forward-facing passengers. Head-flying is bad for neck muscles and bones, as they have to snap the head back in place (would you want to use your neck as a bungee cord?). One recent study reported that newborns to 2-year-olds were 76 percent more likely to be seriously injured in a car crash when they were in forward-facing car seats compared to rear-facing car seats. Seventy-six percent is a lot. In 2011, the American Academy of Pediatrics changed its recommendations to say that kids should remain in rear-facing car seats until at least the age of 2 (they used to say age 1); many state laws are not this strict — they are still, I guess, catching up with the science — but I'd do what the doctors say.

What about booster seats, which the AAP says you're supposed to use for 4 to 7-year-olds who have outgrown their forward-facing harness seats? They don't protect quite as well as the harnessed seats and not nearly as well as rear-facing seats, because they use only the seat belt as a restraint. They are, however, important to ensure that seat belts actually sit where they are supposed to. When kids under 8 wear seat belts without booster seats, the belts can cut across their necks and abdomens, which is precisely where you do not want a massive amount of force to hit your kid. A 2009 study conducted as part of Partners for Child Passenger Safety found that kids between 4 and 8 were 45 percent less likely to sustain moderate to serious injuries in crashes when they were restrained in high-back or backless booster seats to lap-and-shoulder seat belts alone — and this reduction in injury risk went up to 67 percent for kids in post-1998 car models.

What's important to keep in mind, though, when considering all these studies is that parents who use car seats may differ from parents who don't use car seats in many important ways. They may drive safer cars and drive more slowly, for instance, both of which could also influence injury risk. Researchers attempt to control for these confounding factors to isolate the effects of car seats themselves, but these controls are never perfect.

In fact, a small body of research downright contradicts many of the studies I have just mentioned. In 2005, University of Chicago economist Steven Levitt and journalist Stephen Dubner, co-authors of the bestselling “Freakonomics,” published a controversial piece in the New York Times Magazine arguing that “there is no evidence that car seats do a better job than seat belts in saving the lives of children older than 2.” Their assertions were based on several studies Levitt conducted. One mined data from a federal database called FARS, which records the details of U.S. crashes that kill at least one passenger, and found that kids over 2 were no less likely to die in crashes while in car seats than were kids wearing lap-and-shoulder belts. Another Levitt study using crash data from a national database and those of several states found that for kids aged 2 to 6, car seats did not prevent serious injuries any better than lap-and-shoulder belts did. Car seats did, however, reduce the risk of minor injuries by 25 percent.

What gives? Levitt says his results differ from those of earlier studies because data collection in the latter may have been flawed. Information about car seat use and seat belt use in the studies conducted as part of Partners for Child Passenger Safety came from telephone interviews conducted by State Farm Insurance, and “if you were a parent involved in a crash in which your child was injured, and a researcher with your insurance company called you, what would you say if your child was not restrained (i.e., wasn't even wearing a seat belt)?” Levitt asked when we corresponded over email. “You tell the person the kid was using an adult seat belt.” It's seems like a fair point — if people lied and said their kids were in seat belts when they were really not in seat belts, it would make car seats seem more life-saving than they really are. But when the Children's Hospital of Philadelphia researchers designed their experiments, they considered this possibility. Because some crashes were subject to onsite investigations, the researchers were able to compare parent responses with what the investigators actually found — and yes, it's possible to tell when seat belts have been used in a crash, because the belt fabric gets frayed or the buckles get bent. Most of the time, they found, parents told the truth.

The Philly researchers have problems with Levitt's studies, too: The crashes from the FARS database, which he used to calculate fatality risks, may not be representative of the average car crash, because FARS collects data only from crashes that kill at least one passenger. Drivers who get into deadly crashes, the researchers say, are often different from drivers who get into nonfatal crashes-they drive older cars or drive more recklessly, for instance, and reckless drivers may also be more likely to install car seats incorrectly. These facts might explain why, in Levitt's studies, car seats didn't seem to work very well.

It's hard to tease out who's right, but in a way it doesn't matter: Levitt admitted to me that most parents should use car seats. “My own research suggests a slight benefit in car seats reducing injuries, so it probably makes sense for parents to keep using them,” he says. Levitt uses them for his own kids, he says, at least when it's convenient. Ultimately, he says that his goal was never to encourage parents to stop using car seats, but rather to nudge the government into investing in research on better child restraint technologies.

Right now, though, what is the best technology? All car seats have to adhere to federal regulations, so don't worry about buying a dud. I said “buying,” because you shouldn't accept hand-me-downs; most car seats expire after about six years, in part because the plastic and harness webbing degrade from heat and cold. As far as I could find out, there are no comprehensive online databases matching best and worst car seats to various car models, but the National Highway Traffic Safety Administration does rank many popular car seat models for “ease of use,” which includes whether they are compatible with most cars and whether their installation manuals are actually decipherable. (Most aren't: One study reported that car seat manual instructions “exceed the reading skills of most American consumers.” Yes, scientists actually study these kinds of things.)

If you're a safety-conquers-all kind of parent, remember this simple rule: Don't graduate your kid to the next type of safety seat until you absolutely have to, because “every time you transition, you're going to lose a little bit of protection,” Hoffman, the Oregon pediatrician and car seat specialist, says. So if you're in the market for an infant car seat, consider one that has a high rear-facing weight limit — there are a bunch now that go up to 40 pounds, the average weight of a 4-and-a-half-year-old boy — because the longer your kid can sit facing backward, the safer he will be. (And don't worry about his scrunched-up legs getting hurt in an accident: more leg injuries occur when kids are in forward-facing car seats. That said, height does matter, because your kid's head needs to rest at least one inch below the top of a rear-facing seat.) It may sound crazy to you to keep your 3-and-a-half-year-old rear facing, not to mention it being a pain in the ass when it comes to passing back snacks. But in Sweden, most kids are rear-facing until age 4, and when Volvo's insurance company analyzed the data from Swedish car crashes from 1976 to 1996, they concluded that kids up to age 4 in rear-facing seats are 20 percent less likely to be injured than kids in forward-facing seats. (Likewise, try to keep your toddler in a forward-facing harness seat as long as possible before moving to a booster seat.)

But if you, like me, are the parent of a 2- or 3-year-old who currently sits in a forward-facing harness seat, don't go out right now and buy a new seat that will let your child “regress” back to the last stage. I floated this possibility by one of my sources and he basically told me to chill out: Although rear-facing seats are safer, dangerous accidents are uncommon, and forward-facing seats aren't unsafe.

Once you've got your car seat, there's the question of where and how you should install it. I'm not going to give installation pointers — you really don't want to get them from me — but here are some general thoughts. The middle rear seat is actually the safest: Kids who ride there are 43 percent less likely to sustain injuries in a crash compared to kids riding on either side. But keep in mind that you'll have to secure a middle seat using a seat belt, not LATCH, because middle seats don't have LATCH anchors. (Rest assured, experts say: Seat belts work just as well as LATCH.) Speaking of LATCH, though, recommendations are changing. You should either weigh your car seat or contact your seat manufacturer to find out how much your model weighs; once your kid's weight plus the weight of the seat exceeds 65 pounds, start securing the car seat with seat belts instead of LATCH. And if you do use a seat belt to secure your seat, you should still attach the top tether on your car seat to the rear LATCH anchor, as this keeps the seat top from flying forward during a crash. But never, ever attach a car seat using the side LATCH clamps and the seat belt. Is your head spinning yet?

I lied. I am going to give you one pointer on installation. If you have any trouble with it, or even if you don't, there are more than 4,000 locations around the U.S. that will check and fix your car seat installation for free. Confident that you did it right? Don't be. When Mark Zonfrillo — the leader of Child Road Traffic Safety Research at the Children's Hospital of Philadelphia Center for Child Injury Research and Prevention — needed to install a car seat for his daughter, he didn't trust himself. You read that right: A man who studies car seats for a living was not confident enough to install his daughter's car seat. (Why do car seats have to be so intractable? Part of the problem is that back seat designs vary — so there is no “one size fits all” way to install them, and manuals have to cover all the bases. Sometimes, apparently, you even need to use pool noodles to get the angles right.) “This is how challenging the process is,” Zonfrillo says. “Despite having the vehicle manual, the car seat manual and being in the business, I still wanted to have someone else — who has done this many more times than I have, and who knows the nuances and details — do it.” Kids trump pride. Always.