The ALSPAC cohort has frequently been used to study subpopulations and controls identified in a variety of ways, including by genotype (e.g. smoking-related genotypes used for recall of sample for detailed assessment of smoking style), environment and/or phenotype. These have included qualitative projects (young people’s views on record linkage, drug use in teenagers) and quantitative projects (e.g. bone fractures,12 physical exercise13 and diet, children and siblings in families with parental separation14). The ALSPAC sample has also been used to select cases for inclusion in randomized control trials including the value of thermometers in a child’s nursery and comparisons between two designs of orthoptic screening for visual defects (as part of the CiF 4–37-month clinics).15
