Cardiorespiratory patterns in siblings of babies with sudden infant death syndrome.

Clinical data and 24 hour tape recordings of electrocardiogram (ECG) and abdominal breathing movements were collected from 301 infants who had had a sibling who had suffered the sudden infant death syndrome (SIDS). Of these, 261 were referred cases, and 40 were recorded prospectively as part of a population based study; none of the 301 subsequently died. Fifty five of the referred siblings who had been born at full term (greater than or equal to 37 week gestation) were randomly selected for a detailed analysis of heart rate and breathing patterns, as were all siblings born at full term from the prospective study (16 with a previous sibling in whom SIDS had occurred and seven with a sibling born at full term and in whom SIDS had subsequently occurred). The control group consisted of 197 recordings on 170 infants born at full term and matched by postnatal age. The mothers of the siblings smoked and consumed alcohol more often during pregnancy than the mothers of control babies. The siblings had lower Apgar scores and were more often breast fed than controls. There were no significant differences in the number of apnoeic pauses in the quantities of periodic breathing or in the heart and respiratory rates during regular breathing between the siblings and the controls.