While many teens celebrate getting their license, parents are likely less thrilled about their son or daughter heading out on the road for the first time. Safety among teen drivers is a major concern, especially since a recent study confirmed having other passengers in the car can increase the risk of fatal accident.

The AAA Foundation for Traffic Safety released a new study looking at the effects of having other passengers under the age of 21 in the vehicle. Driving with friends may be a major distraction for teen drivers, as the risk of an accident went up sharply the more people were in a vehicle.

With one person under 21 in the vehicle in addition to the driver, the risk of a fatal accident rose by 44 percent. At two passengers younger than 21, the risk doubles. The rate quadruples with three or more passengers in the car.

"We know that carrying young passengers is a huge risk, but it's also a preventable one," said Beth Mosher, director of public affairs for AAA Chicago. "These findings should send a clear message to families that parents can make their teens safer immediately by refusing to allow them to get in the car with other young people, whether they're behind the wheel or in the passenger seat."

Parents should also be sure their teen's vehicle is up-to-date on scheduled maintenance, as missing key auto repairs can make a car dangerous to drive.