To the Editor.—The paper by French et al1 affords some support to the hypothesis that nasal obstruction in the infant, unable to breathe thru his mouth, is a potential cause for sudden infant death (SID). Many animals have difficulty with oral respiration especially in early life: horses, kittens, rats, etc, but baby monkeys provide a primate model in which to explore this hypothetic cause of SID. Regrettably the resultant apnea reported by the authors was treated by resuscitation and thus did not provide autopsy evidence which might resemble that found in affected human infants.
According to their evidence, most monkeys learn to breathe orally at 10 to 12 weeks of age. Most human infants are obligatory nasal breathers at birth and gradually thru succeeding weeks learn to mouth breathe as a voluntary skill by 5 months of age. SID is significantly limited to this age span.