Child restraint systems for cars are intended to protect children in the case of a car accident. Unfortunately their effectiveness is still too low; in the range 30-50% which it would be expected to be about 70-80%. Consequently there are high mortality and morbidity rates even in countries which have stringent regulation and where the use of child restraint systems in mandatory from birth to 10 or 12 years.
Each year in the USA, about 1,800 children under age 14 die in motor vehicle crashes, and more than 274,000 are injured, according to data from the National Traffic Highway Safety Administration. Statistics suggest that with or without laws, about three in 10 children ages 4 and under ride without any restraint at all and of those children who are buckled up, four of five are not restrained correctly. The leading cause of death for children aged 5-16 is motor vehicle crashes. These children are too big for child safety seats and too small for regular seat belts. They often travel unrestrained or imperfectly restrained. In the 1990s, about 832 children between 4 and 8 were killed each year in motor vehicle accidents. In 1999, more than 70% of the children who died were totally unrestrained. Those between around 5 and 10 years are are the prime candidates for booster seats, which raise children so they are more properly positioned into seat belts. Booster seats are appropriate for around 19.5 million children in the USA, but their use is a fraction of the need.
The low effectiveness of child restraint systems can partly be explained for the youngest passengers by their greater cervical vulnerability and for the oldest (3-12 years) by the morphological immaturity of the pelvis.