Is sudden infant death syndrome still more common in very low birthweight infants in the 1990s?

OBJECTIVE: To determine the rate of sudden infant death syndrome (SIDS) in very low birthweight children (VLBW) relative to children with low (LBW) and normal birthweights.

DESIGN, SETTING AND SUBJECTS: Cohort study of consecutive live births in Victoria, 1993-1997 inclusive.

MAIN OUTCOME MEASURES: All sudden unexpected deaths in early childhood over this five-year period; all deaths from SIDS (defined as a sudden unexpected death without a definite pathological explanation); and the proportion of SIDS in live births in three birthweight subgroups (VLBW, 500-1499 g; LBW, 1500-2499 g; and normal birthweight, > 2499 g).

RESULTS: There were 316,028 live births (with known birthweight) in Victoria over the five-year period; 224 (0.71 per 1000 live births) died unexpectedly. In 10 of these deaths there was a definite pathological explanation, giving a rate of SIDS of 0.68 per 1000 live births. The rate of SIDS in VLBW children was 2.52 per 1000 live births, lower than the rate reported before the 1990s. The rate of SIDS in VLBW children was not significantly different from the rate in LBW children of 1.98 per 1000 live births (difference per 1000 live births, 0.53; 95% CI, -1.45 to 2.52), but was significantly higher than the rate in normal birthweight children of 0.59 per 1000 live births (difference per 1000 live births, 1.93; 95% CI, 0.06-3.79).

CONCLUSIONS: The rate of SIDS in VLBW children has fallen in the 1990s, along with the overall fall in the rate of SIDS, but remains higher than that in normal birthweight children.