Prone sleeping reduces cerebral oxygen in infants

Putting infants to sleep in the prone position reduces cerebral oxygenation, which may help to explain why this sleeping position is associated with an increase in the incidence of sudden infant death syndrome (SIDS), say Australian researchers.

Their findings appear in the March issue of Pediatrics.

The exact mechanism behind SIDS is uncertain. Previously, these same investigators discovered that when infants sleep in the prone position, they are 3 times more difficult to arouse from sleep. In their new research, 17 healthy term infants who routinely slept in the supine position at home were studied in both the supine and prone sleeping positions in a sleep laboratory using daytime polysomnography, during which they also had cerebral tissue oxygenation index (TOI) measured.

The infants were studied at 3 times: 2 to 4 weeks old (when the risk of SIDS is low), 2 to 3 months old (when the risk of SIDS peaks), and 5 to 6 months old (when the risk of SIDS is low again).

Infants sleeping in the prone position had a significantly lower TOI during both quiet sleep and active sleep at age 2 to 4 weeks (5% lower TOI; P PP

“Clinically, low cerebral oxygenation may contribute to the high risk for SIDS associated with prone sleeping,” the researchers write. “Notably, reductions in overall arousability from sleep occur in infants sleeping in the prone position, a deficit which has been proposed as one of the mechanisms underlying SIDS.”

During early neonatal life, infants’ capacity for additional increases in oxygen extraction may be diminished in the event of coincident hypoxic stress, hypotension, and cerebral hypoperfusion, they speculate.

Wong FY, Witcombe NB, Yiallourou SR, et al. Cerebral oxygenation is depressed during sleep in healthy term infants when they sleep prone. Pediatrics. 2011;127(3):e558-e565.