Results are reported from a three-year (1 March 2012 to 28 February 2015) nationwide casecontrol study conducted in New Zealand that sought to identify modifiable risk factors for sudden unexpected death in infancy (SUDI). Over the study period, 137 SUDI cases were recorded, resulting in a SUDI mortality rate of 0.76/1,000 live births. Māori had the highest rate (1.41/1,000) versus Pacific (1.01/1,000) and non-Māori non-Pacific (predominantly European; 0.50/1,000). Interviews were conducted with the parent(s) of 97% of the SUDI cases and with 258 controls. The two major risk factors for SUDI were maternal smoking in pregnancy (adjusted OR 6.01; 95% CI, 2.97 to 12.15) and bed sharing (adjusted OR 4.96; 95% CI, 2.55 to 9.64). There was a significant interaction (p=0.002) between bed sharing and antenatal maternal smoking. Infants exposed to both risk factors were at substantially greater risk of SUDI (adjusted OR 32.8; 95% CI, 11.2 to 95.8) compared with infants not exposed to either risk factor. Infants not sharing the parental bedroom were also at increased risk of SUDI (adjusted OR 2.77; 95% CI, 1.45 to 5.30). Just 21 cases in the entire study were not exposed to smoking in pregnancy, bed sharing or front or side sleeping position.
