In both cohorts, children’s history of unintentional injuries was ascertained from parents at Wave 2, or at the child’s age of 18 months, with the question: “Did your child experience unintentional injuries during the past 12 months?”. Respondents who confirmed their child’s experience of unintentional injuries were then asked to select the type(s) of injury from the following 10 options: 1) a fall from bed, stairs, etc; 2) trapped an arm or a leg between doors or windows; 3) cut with a sharp object such as a knife; 4) bitten by an animal or stung by a bee; 5) drowned or near-drowned; 6) swallowed a small object, such as a coin or cigarette; 7) inserted a small object into the eye, ear, or nose; 8) burnt by a hot object such as a hot iron; 9) had a traffic accident, and 10) other injury. Children’s history of hospital admissions was also ascertained from the parents at Wave 2 with the question: “Was your child admitted to hospital during the past 12 months?”. We assessed the injury outcome at Wave 2 and hospital admission outcomes at Waves 2 and 6 in the 2001 cohort (representing 18- and 66-month longitudinal follow-ups). Similarly, in the 2010 cohort, we assessed injury and hospital admission outcomes at Wave 2. The wording of ascertainment on unintentional injuries and hospital admissions remained exactly the same from the 2001-cohort survey to the 2010-cohort survey.