This threat to pregnant women is on roads everywhere

Here’s one more pregnancy hazard: speed bumps.

An eyebrow-raising paper from engineers at the University of British Columbia reports that a vehicle driving at moderate speeds over a speed bump could potentially damage a passenger fetus. The findings show that the force of a vehicle driving more than 27 mph over a speed bump is too high for fetal organs, particularly brains.

So what speed is safe? No faster than 15 mph at the speed bump.

The potential risks to a fetus are not pretty: minor fetal brain injury, abnormal fetal heart rate, uterine contractions, abdominal pain, pregnancy complications, and—as you would expect—increased uterine activity. The researchers note that speed bump physics vary widely based on vehicles, bumps, and mothers. But they say that caution is prudent for all expectant moms.

The research is published in the Journal of Biomechanics, which should catch your eye, as this is an atypical location for pregnancy risk research. Before fretting, realize that this study was carried out by an engineer who modeled crash test data on an imagined 32-week fetus—and not, say, randomized, controlled research by a high-risk pregnancy expert who measured impact forces on an actual pregnant woman and her fetus. This said, the findings are both foreseeable and alarming: The fetal impact from a vehicle hitting a speed bump at 35 or 40 mph is quite high.

Drivers everywhere, unconcerned with the well-being of their vehicle suspensions, commonly put the “speed” in speed bump; this writer once commuted daily with a driver who enjoyed hotfooting it over a speed bump atop a hill at 55-60 mph, resulting in airborne flight and hard landings.

These findings are particularly concerning for women traversing the unpaved, exceedingly bumpy roads of developing nations, where van and motorbike drivers commonly careen along at high speeds for hours with pregnant women on board.