Safety is always a concern and particularly with young children.  I generally read up reports on safety and access Arrive Alive figures and the like.  A recent report in the Pediatrics journal, said that while there are obstacles to placing a child's seat in the middle, that is the safest position for it in the event of an accident.  Their report indicated children were 43% less likely to be injured that if the seat was placed at the side of the vehicle.  This was to an extent because the child would be better positioned in the event of a side-impact crash.