Males account for four out of five traumatic spinal cord injuries. Most of these injuries occur in men under 30 years of age. The average age at the time of injury has slowly increased from about 29 years in the 1970s to 41. Rates of injury are at their lowest in children, at their highest in the late teens to early twenties, then get progressively lower in older age groups; however rates may rise in the elderly. In Sweden between 50 and 70% of all cases of SCI occur in people under 30, and 25% occur in those over 50. While SCI rates are highest among people age 15–20, fewer than 3% of SCIs occur in people under 15. Neonatal SCI occurs in one in 60,000 births, e.g. from breech births or injuries by forceps. The difference in rates between the sexes diminishes in injuries at age 3 and younger; the same number of girls are injured as boys, or possibly more. Another cause of pediatric injury is child abuse such as shaken baby syndrome. For children, the most common cause of SCI (56%) is vehicle crashes. High numbers of adolescent injuries are attributable in a large part to traffic accidents and sports injuries. For people over 65, falls are the most common cause of traumatic SCI. The elderly and people with severe arthritis are at high risk for SCI because of defects in the spinal column. In nontraumatic SCI, the gender difference is smaller, the average age of occurrence is greater, and incomplete lesions are more common.