You’d think spotting SIDS would be fairly straightforward, but it’s not. It’s very hard to know exactly how and why babies succumb, or why the highest rates occur in infants between 2 and 4 months old. The condition can be diagnosed only when a death has been carefully investigated—including an autopsy, a study of the scene and circumstances of death, and an examination of the baby's medical history—so that all other possibilities can be ruled out. And even then, it can be a challenge. For instance, when a baby is found lying on her tummy—or in a bed where adults slept, or a crib full of soft toys—the coroner can't rule out the possibility that the baby was accidentally smothered.