What makes women more prone to car accident injuries than men?

A research team from the University of Virginia recently published a study showing that women are 73% more likely to suffer serious injuries or be killed in auto accidents. This was true even when controlling for the model year of their cars, their height, weight and BMI, their age and their proximity to the steering wheel.

Researchers have long known that women are more likely than men to be injured in similar car crashes. We’ve also known that women’s bodies are not just smaller versions of men’s bodies. There are important differences in a variety of bio-mechanical ways.

The mechanical properties of women’s bones and ligaments could potentially change the way that seat belts work. Their pelvises are wider and shallower than men’s. Women carry their weight differently, with more body mass concentrated in the waist and thighs. Hormonal variations could even affect how stiff their tissues are and how susceptible they are to injury, according to one of the study’s authors.

We know that women are different from men in crucial ways, and we know that they’re more vulnerable in auto wrecks. What we don’t know is exactly why.

Safety tests often don’t take women into account

For years, automakers and insurance companies tested car safety using only male crash test dummies. This hasn’t been useless to women; safety advancements over the last couple of decades have resulted in safety improvements for everyone.

Indeed, the study’s authors found that the occupants of vehicles manufactured in 2009 and later were less than half as likely to be seriously injured or killed than people in older vehicles.

Yet female crash test dummies have only been in use since the early 2000s — and they only represent the very small end of the female spectrum. The typical female crash test dummy is 5 feet tall and weighs 110 pounds — far from average.

More advanced female crash test dummies are being developed, but they can’t be created overnight. The dummies are based on decades of bio-mechanical data, and that data simply doesn’t exist when it comes to women.

Even if scientists had decades of bio-mechanical data about women, creating a better female dummy could still take a decade or more. That is because the results from dummy tests need to be validated with data from real-world crashes.

In the last decade or so, safety testing has become more computerized and relies less on physical crash test dummies — but computer models are only as good as the bio-mechanical data they represent.

We need to fix this moving forward. Without good data on women and their differences, we’ll probably continue to see women being 73% more vulnerable in car accidents.