Background
Children who are exposed to adversities might be more susceptible to disease development during childhood and in later life due to impaired physiological and mental development. To explore this hypothesis, we assessed hospitalisation patterns through childhood and into adult life among those exposed to different trajectories of adversities during childhood.

Methods
For this population-based cohort study, we used annually updated data from Danish nationwide registers covering more than half a million children (aged 0–15 years) born between 1994 and 2001. Children who were alive and resident in Denmark on their 16th birthday were included in the analysis. Cluster analysis was used to divide children into five distinct trajectories according to their experience of childhood adversities, including poverty and material deprivation, loss or threat of loss within the family, and aspects of family dynamics. To describe comprehensively the disease patterns experienced by these groups of children, we assessed the associations of each adversity trajectory with hospital admission patterns according to the entire spectrum of disease diagnoses in the International Classification of Diseases 10th edition, from birth to 24 years of age, using survival models.

Findings
508 168 children born between Jan 1, 1994, and Dec 31, 2001, were followed up until Dec 31, 2018, capturing more than 3·8 million hospital admissions from birth to early adulthood. Hospitalisation rates were consistently higher in all four adversity groups compared with the low adversity group. The high adversity group (14 577 children, 3%), who were exposed to adversities of deprivation, family loss, and negative family dynamics, had a markedly higher rate of hospitalisations across all ages. For example, we observed 243 additional hospital admissions per 1000 person-years (95% CI 238–248) in the high versus low adversity group for those aged 16–24 years. These associations were particularly strong for diagnoses related to injuries, unspecified symptoms, and factors influencing health service contacts (eg, health screening and observation). They also covered a considerable burden of respiratory and infectious diseases, congenital malformations, diseases of the nervous system (especially in early life), mental and behavioural diagnoses, and diagnoses related to pregnancy and childbirth in early adult life.

Interpretation
The close linkage between childhood adversities and poor lifelong health outcomes highlights a need for public health and policy attention on improving the socioeconomic circumstances children are born into to prevent the early emergence of health inequalities.