Lung function trajectories from birth to school age in African children, and their early life determinants Lung diseases are a major cause of ill health and premature death globally, with a particularly large burden in Africa. Asthma and chronic obstructive pulmonary disease (COPD) are very common, and COPD is the third biggest killer in Africa. African patients develop more severe asthma and COPD, and at a younger age, compared to the rest of the world.   Low level of lung function in young adult age is an important risk factor for the development of COPD. Furthermore, low lung function increases the likelihood of early death from all causes as early as the third decade of life. Studies from high-income countries have shown that lung function tracks from school age to old age, and that lung function in early childhood is an important determinant of COPD in adulthood. Childhood asthma and lower respiratory tract infections in early life reduce lung function through childhood.  The burden and the type of respiratory infections and asthma, as well as environmental factors which adversely affect development of lung function (such as cigarette smoke, biomass exposure, allergens or psychosocial stressors), are markedly different in Africa compared to the high-income countries. However, despite the high frequency and severity of childhood asthma, high incidence of respiratory infections, and many harmful environmental exposures, to date there are no data on early-life factors associated with poor lung function and its trajectory in Africa.  We have shown that there is a scope to intervene in early childhood to improve lung function, and reduce long-term consequences of low lung function in childhood. In order to develop interventions to reduce the risk of low lung function in the needy population in Africa, we have to identify childhood lung function trajectories, and discover their early life environmental determinants, which are specific to this part of the world. This information is crucial to develop novel preventative strategies in this part of the world, which will impact on COPD, and the other adverse consequences of diminished lung function.    Our overall aim is to investigate lung function trajectories in African children from birth to 8 years of age, and to identify early-life risk factors associated with low lung function trajectory. We will focus on early-life exposures and respiratory outcomes during childhood, as the trajectory of long-term lung health is established in early life. To achieve this, we will build on the unique South African birth cohort of 1000 mother-child pairs, with detailed measures of infectious diseases and non-infectious exposures through pregnancy and childhood, extensive biobank of samples, and longitudinal measurements of lung function and respiratory diseases from birth to age 5 years. In the course of this project, we will measure lung function and the progression or severity of clinical symptoms through to age 8 years, with ongoing collection of environmental exposures.  This will extend the number of time points at which clinical symptoms and lung function have been measured in an identical way, and lay foundations for longitudinal analyses, thereby creating a unique resource unparalleled anywhere in low-income and middle-income countries.   We will bring together leading UK and South African experts, to investigate lung function trajectories in South African children from birth through age 8 years, and determine early life exposures which lead to the low lung function. We will build African research capacity through collaborations and training between South African and UK expert groups.   Our overall vision is to inform the development of intervention strategies to reduce the risk of low lung function trajectories during the growth phase, and prevent multi-organ morbidity and premature death in African populations, an area of critical need. The Global Challenges Research Fund (GCRF) supports cutting-edge research to address challenges faced by developing countries. The fund addresses the UN sustainable development goals. It aims to maximise the impact of research and innovation to improve lives and opportunity in the developing world.