The original cohort of 1037 children (52 % males) represents the general population of New Zealand’s South Island in the early 1970s. To be eligible for inclusion participants had to be living in the greater Dunedin Metropolitan area 3 years after their birth at Queen Mary Maternity Hospital—the only maternity hospital in Dunedin at the time. The 9 % who declined or were unable to participate were no different from the 91 % who agreed to take part in terms of maternal prenatal complications, birthweight, neonatal complications or family socioeconomic status [9]. Cohort families represented the full range of socioeconomic status in New Zealand in the early 1970s, as compared to the New Zealand census. Cohort members were primarily white: 7.5 % self-identify as being Māori which matches the ethnic distribution of the South Island of New Zealand. Importantly, we have published evidence that half-a-lifetime of research participation has not improved Study members’ mental or physical health as compared to same-aged participants in the New Zealand National Health and Nutrition Survey’s (e.g. BMI, smoking, visits to the doctor) [10]. Day-long
