SLEEPING POSITION AND SUDDEN-INFANT-DEATH-SYNDROME IN NORWAY 1967-91

Objective-To investigate, in a population based national study, the association between sleeping position of infants and the occurrence of sudden infant death syndrome (SIDS). Design-A retrospective survey and registry based ecological study. A questionnaire based surveillance of sleeping position was obtained in a random sample (n=34 799) and surveillance of SIDS was based on all infants born in Norway 1967-91, surviving the perinatal period. Variables studied from the questionnaire were usual sleeping position (placed), breast feeding at 3 months, and maternal smoking in pregnancy, and from the Medical Birth Registry maternal age, birth order, and birth weight. Results-Proportion of infants sleeping prone increased from 1970 (7.4%) to 1989 (49.1%) and dropped in 1990 (26.8%) and 1991 (28.3%). Occurrence of SIDS increased from 1970 (1.1/1000) to 1989 (2.0) before dropping in 1990 and 1991 (1.1). Implication and relevance of results-A cause effect relationship between prone sleeping and SIDS as suggested in previous studies is supported by the present, and so far only, national study of infants' sleeping position.