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. In an attempt to resolve these conflicting findings we analysed heart rate and breathing patterns on 24 hour tape recordings of ECG and abdominal breathing movements on 78 siblings of cases of SIDS who had been born at full term (:37 weeks' gestation), and 170 age matched controls who had also been born at full term. We also include a comparison of prenatal and early postnatal clinical data between these 78 siblings and their 170 controls. PatientsControls. A total of 197 24-hour tape recordings of ECG and abdominal wall movements were performed on 170 control infants. These infants were born at one of four hospitals, were born at full term (¢37 weeks' gestation), and were chosen to cover the same age range as the siblings. A proportion was from a previously reported sequential control group;"l a second group was randomly selected from surviving infants being studied as part of a prospective investigation into SIDS;'2 and a small group of older infants was chosen randomly from a local health visitors' clinic in Doncaster.Prenatal and early postnatal clinical data were compiled from hospital notes and questionnaires given to parents at the time of the recordings. Four 721 on 7 May 2018 by guest. Protected by copyright.

A total of 305 infants presenting with apparent life-threatening events (ALE) were referred by their paediatricians and underwent 24-hour tape recordings of electrocardiogram and abdominal breathing movements (from a pressure capsule transducer). Seventy-seven of these infants, all full-term (≥ 37 weeks of gestation), were randomly selected, followed up for clinical outcome, and their recordings subjected to a detailed analysis of heart and respiratory rates and breathing patterns. Recordings on 157 age-matched, full-term controls were similarly analysed for comparison purposes. One of the 77 patients suffering from ALE had a pre-existing neurodevelopmental problem, and 4 more cases showed this at follow-up, including 1 case whose ALE was subsequently diagnosed as originating from non-accidental injury. Compared with controls and as a group, the patients suffering from ALE showed higher numbers of apnoeic pauses (p < 0.001), larger quantities of periodic breathing (p < 0.01) and lower respiratory rates during regular breathing (p < 0.01).