Maturation of long-running birth cohort studies has fostered a life course approach to adult health, function, and disease and related to conceptual frameworks. Using broad concepts of human development including physical, cognitive, and emotional function, birth cohorts provide insights into the processes across the life course and between generations that link to adult outcomes. We discuss findings on the determinants and health consequences of lifetime trajectories of body size, cognitive and emotional function, and socioeconomic position. Findings from the studies suggest that, for some adult health outcomes, explanations will be incomplete unless exposures and processes from across the life course are taken into account. New birth cohort studies are poised to delineate further the nature and timing of life course relationships in contemporary generations of children.

There is growing recognition that the risk of many diseases in later life, such as type 2 diabetes or breast cancer, is affected by adult as well as early-life variables, including those operating prior to conception and during the prenatal period. Most of these risk factors are correlated because of common biologic and/or social pathways, while some are intrinsically ordered over time. The study of how they jointly influence later (“distal”) disease outcomes is referred to as life course epidemiology. This area of research raises several issues relevant to the current debate on causal inference in epidemiology. The authors give a brief overview of the main analytical and practical problems and consider a range of modeling approaches, their differences determined by the degree with which associations present (or presumed) among the correlated explanatory variables are explicitly acknowledged. Standard multiple regression (i.e., conditional) models are compared with joint models where more than one outcome is specified. Issues arising from measurement error and missing data are addressed. Examples from two cohorts in the United Kingdom are used to illustrate alternative modeling strategies. The authors conclude that more than one analytical approach should be adopted to gain more insight into the underlying mechanisms.

The longitudinal study, ‘Growing Up in New Zealand’, was explicitly established to provide contemporary, population-relevant evidence about the multi-disciplinary determinants of pathways towards health and development for children born in the 21st century New Zealand. Improvements in child health have been slower in New Zealand in recent decades relative to other developed countries, and in 2009 New Zealand was ranked 29th out of 30 OECD countries.¹ Examples of child health indicators where New Zealand performs relatively poorly include infant mortality rates, immunization coverage, accidents and injuries in under 5-year-olds, rates of child maltreatment and hospital admission rates for a spectrum of communicable diseases including pertussis, pneumonia and rheumatic fever.^1–4