Heavy caffeine consumption in pregnancy, smoking, and sudden infant death syndrome

Editor,—Ford and his colleagues in New Zealand found that consumption of ⩾400 mg of caffeine during the third trimester was associated with an increased risk of sudden infant death (SIDS) months after birth.1 Consumption of lower concentrations of caffeine were not associated with any increased risk of cot death. The lack of a dose-response relation between maternal caffeine consumption and risk of cot death should have alerted the authors to the possibility that the relation is not causal. Nevertheless, the authors proceeded to seek biological explanations for their findings. Let me offer an epidemiologist’s interpretation. The risk of SIDS has repeatedly been increased among infants exposed to parents’ cigarette smoke, often in a dose-response pattern.2 3 Thus, parents’ smoking should be viewed as an important risk factor for SIDS. The authors classified maternal smoking during pregnancy as a yes/no variable. Maternal smoking during the months preceding the interview was not assessed, nor was paternal cigarette smoking. As the greater …