Sudden death of an infant younger than age 1 year without identifiable cause

Occurs in approximately 2 out of every 1,000 live births; about 60% are males

Increasing incidence in non–breast-fed infants and infants who sleep on their stomachs

Slightly higher incidence in preterm neonates, Inuit neonates, disadvantaged Black neonates, neonates of mothers younger than age 20, neonates of multiple births, neonates of mothers who smoked during pregnancy, and neonates exposed to second-hand smoke

Most commonly occurs in fall and winter

Also known as SIDS, crib death, and cot death

The infant may have damage to the respiratory control center in the brain from chronic hypoxemia.

The infant may not respond to increasing carbon dioxide levels; during an episode of apnea, carbon dioxide levels increase, but the child isn’t stimulated to breathe; as apnea continues, high levels of carbon dioxide further suppress the ventilatory effort until the infant stops breathing.

The infant may have periods of sleep apnea and eventually die during one of these episodes.

Apnea theory

Hypoxia theory