QT interval measurements before sudden infant death syndrome.

Standard electrocardiogram recordings were performed on a total of 7254 newly born infants from two maternity hospitals. Fifteen recordings were obtained on 15 infants who subsequently suffered sudden infant death syndrome. None showed lengthening of QT intervals sufficient to warrant the description of 'long QT syndrome'. When the QT intervals corrected for heart rate of cases with sudden infant death syndrome were compared with controls in age matched groups or after individual matching for postnatal age, hospital of birth, and weight at birth, no significant differences could be identified.