Maternal and antenatal factors in the risk of sudden infant death syndrome.

The prenatal course, labor and delivery of 90 mothers of infants who died of Sudden Infant Death Syndrome (SIDS) in Connecticut from 1974 through 1976 were studied by hospital chart reviews. Charts of 90 pair-matched controls whose infants survived the first year of life were also examined. Significant associations were found between SIDS and: 1) maternal age under 20 years, 2) later initial prenatal visit, 3) maternal blood type O, 4) reported conditions during the pregnancy. The racial distribution of the infants of the study population differed significantly from the distribution of births in Connecticut during these years, with a higher than expected proportion of blacks among the case infants. Male infants in the study population outnumbered females three to two, and cases weighed an average of 430 grams less than controls at birth.