New risk factors for autism have been identified, and they all have to do with birth. Children who are firstborn or were born breech, or whose mothers were over 34 when they were delivered, all face roughly twice the chance of developing the brain disorder, which affects communication and social skills. The University of Utah researchers who made the discovery plan on replicating their study to see if they find similar results. They’re not sure why these prenatal factors influence the risk of autism. Genetics and neuromuscular dysfunction may be part of the explanation.