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The impact of early life exposures on lung function in African preschool children
Respiratory disease substantially impacts global health in children with the highest burden in low- and middle-income countries (LMIC). Pneumonia is a leading cause of death in children under five years, while chronic respiratory disease is a major contributor to non-communicable disease burden acro...
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| Format: | Thesis |
| Language: | English English |
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Department of Paediatrics and Child Health
2026
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| _version_ | 1869483676367060992 |
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| access_status_str | Open Access |
| author | Chaya, Shaakira |
| author2 | Gray, Diane |
| author_browse | Chaya, Shaakira Gray, Diane |
| author_facet | Gray, Diane Chaya, Shaakira |
| author_sort | Chaya, Shaakira |
| collection | Thesis |
| description | Respiratory disease substantially impacts global health in children with the highest burden in low- and middle-income countries (LMIC). Pneumonia is a leading cause of death in children under five years, while chronic respiratory disease is a major contributor to non-communicable disease burden across the life-course. Early lung function is crucial for respiratory health, with low lung function in childhood linked to higher risks of respiratory and cardiovascular disease and premature mortality later in life. Lung growth occurs rapidly from birth to school age, yet most cohort studies have measured lung function later in childhood or adulthood. Until recently, tools for measuring preschool lung function have been limited. Additionally, much of the available data comes from cohorts in high-income countries. Many factors known to be associated with poor respiratory health such as indoor air pollution (IAP), environmental tobacco smoke (ETS) and preterm birth are prevalent in LMIC. However, data on the early life impact on lung health in these settings are lacking. Emergent pulmonary function tests, feasible in preschool children, have the potential to fill this gap. This thesis aimed to investigate the determinants of preschool lung function in South African children enrolled in a birth cohort, the Drakenstein Child Health Study (DCHS). All 1143 children followed from birth who had infant lung function were included in the study, with lung function measured yearly between 3 to 5 years. Lung function measurements included tidal breathing, multiple breath washout and pre- and post-bronchodilator oscillometry and spirometry (from 5 years). At each visit, parents completed a questionnaire which assessed socioeconomic factors, smoking and exposure to passive cigarette smoke, current and past health history including lower respiratory tract infection (LRTI), HIV status and treatment history. Air pollutants were measured antenatally and at 4 to 6 months postnatally and included particulate matter 10, carbon monoxide, nitrogen dioxide, sulphur dioxide and volatile organic compounds. The chapters of the thesis cover: (1) A review of the need for and feasibility of lung function tools in preschool children, contributing to addressing the gap in our understanding of lung growth and development and its determinants during the preschool period. The results show that preschool lung function measurements are largely under-represented in LMIC, but feasible for clinical and epidemiological use, raising the potential of tracking lung function from early life through to adulthood and bridging the gap during the critical preschool period. The lack of suitable reference ranges for interpretation is highlighted, particularly for emergent preschool tests such as oscillometry. (2) Deriving the first reference equation for oscillometry in African children using a cohort of 690 healthy children between 3 and 17 years. (3) Investigation of the joint impact of antenatal and postnatal environmental exposures on lung development through to 3 years. These analyses show that both antenatal and postnatal IAP and ETS exposure impair lung function at 3 years. The effects of postnatal exposures on lung function were independent and additional to that of antenatal exposures, an important finding as these are modifiable factors. (4) The impact of preterm birth on lung function through 5 years, providing the first longitudinal description of lung function in preterm infant survivors in LMIC. The findings show that these children had impaired lung function trajectories over the first 5 years, notably in the moderate to late preterm group. LRTI and ETS were important modifiable factors contributing to reduced lung function in this vulnerable group. These finding have implications for clinical practice and public health, highlighting the need for improved maternal health initiatives to prevent preterm births, strengthen maternal pre-, peri- and postnatal health and to provide long-term follow-up of children born preterm. Additionally, the importance of educating healthcare professionals about the long-term effects of preterm birth is highlighted. In conclusion, preschool lung function testing was found to be feasible in a LMIC setting. The reference range equation contributed to developing the usefulness of this tool for African children. Major determinants of lung function included LRTI, ETS, and preterm birth. Public health initiatives to enhance maternal health and peri- and postnatal care, and strategies to reduce ETS and early-life LRTI such as novel preventive therapies, should be prioritised in LMIC settings. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/43406 |
| institution | University of Cape Town (South Africa) |
| language | English eng |
| last_indexed | 2026-07-01T04:02:47.092Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| publisher | Department of Paediatrics and Child Health |
| publisherStr | Department of Paediatrics and Child Health |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/43406 The impact of early life exposures on lung function in African preschool children Chaya, Shaakira Gray, Diane Zar, Heather children preschool African Respiratory disease substantially impacts global health in children with the highest burden in low- and middle-income countries (LMIC). Pneumonia is a leading cause of death in children under five years, while chronic respiratory disease is a major contributor to non-communicable disease burden across the life-course. Early lung function is crucial for respiratory health, with low lung function in childhood linked to higher risks of respiratory and cardiovascular disease and premature mortality later in life. Lung growth occurs rapidly from birth to school age, yet most cohort studies have measured lung function later in childhood or adulthood. Until recently, tools for measuring preschool lung function have been limited. Additionally, much of the available data comes from cohorts in high-income countries. Many factors known to be associated with poor respiratory health such as indoor air pollution (IAP), environmental tobacco smoke (ETS) and preterm birth are prevalent in LMIC. However, data on the early life impact on lung health in these settings are lacking. Emergent pulmonary function tests, feasible in preschool children, have the potential to fill this gap. This thesis aimed to investigate the determinants of preschool lung function in South African children enrolled in a birth cohort, the Drakenstein Child Health Study (DCHS). All 1143 children followed from birth who had infant lung function were included in the study, with lung function measured yearly between 3 to 5 years. Lung function measurements included tidal breathing, multiple breath washout and pre- and post-bronchodilator oscillometry and spirometry (from 5 years). At each visit, parents completed a questionnaire which assessed socioeconomic factors, smoking and exposure to passive cigarette smoke, current and past health history including lower respiratory tract infection (LRTI), HIV status and treatment history. Air pollutants were measured antenatally and at 4 to 6 months postnatally and included particulate matter 10, carbon monoxide, nitrogen dioxide, sulphur dioxide and volatile organic compounds. The chapters of the thesis cover: (1) A review of the need for and feasibility of lung function tools in preschool children, contributing to addressing the gap in our understanding of lung growth and development and its determinants during the preschool period. The results show that preschool lung function measurements are largely under-represented in LMIC, but feasible for clinical and epidemiological use, raising the potential of tracking lung function from early life through to adulthood and bridging the gap during the critical preschool period. The lack of suitable reference ranges for interpretation is highlighted, particularly for emergent preschool tests such as oscillometry. (2) Deriving the first reference equation for oscillometry in African children using a cohort of 690 healthy children between 3 and 17 years. (3) Investigation of the joint impact of antenatal and postnatal environmental exposures on lung development through to 3 years. These analyses show that both antenatal and postnatal IAP and ETS exposure impair lung function at 3 years. The effects of postnatal exposures on lung function were independent and additional to that of antenatal exposures, an important finding as these are modifiable factors. (4) The impact of preterm birth on lung function through 5 years, providing the first longitudinal description of lung function in preterm infant survivors in LMIC. The findings show that these children had impaired lung function trajectories over the first 5 years, notably in the moderate to late preterm group. LRTI and ETS were important modifiable factors contributing to reduced lung function in this vulnerable group. These finding have implications for clinical practice and public health, highlighting the need for improved maternal health initiatives to prevent preterm births, strengthen maternal pre-, peri- and postnatal health and to provide long-term follow-up of children born preterm. Additionally, the importance of educating healthcare professionals about the long-term effects of preterm birth is highlighted. In conclusion, preschool lung function testing was found to be feasible in a LMIC setting. The reference range equation contributed to developing the usefulness of this tool for African children. Major determinants of lung function included LRTI, ETS, and preterm birth. Public health initiatives to enhance maternal health and peri- and postnatal care, and strategies to reduce ETS and early-life LRTI such as novel preventive therapies, should be prioritised in LMIC settings. 2026-06-26T13:44:30Z 2026-06-26T13:44:30Z 2026 2026-06-26T13:38:52Z Thesis / Dissertation Doctoral PhD http://hdl.handle.net/11427/43406 en eng application/pdf Department of Paediatrics and Child Health Faculty of Health Sciences University of Cape Town |
| spellingShingle | children preschool African Chaya, Shaakira The impact of early life exposures on lung function in African preschool children |
| thesis_degree_str | Doctoral |
| title | The impact of early life exposures on lung function in African preschool children |
| title_full | The impact of early life exposures on lung function in African preschool children |
| title_fullStr | The impact of early life exposures on lung function in African preschool children |
| title_full_unstemmed | The impact of early life exposures on lung function in African preschool children |
| title_short | The impact of early life exposures on lung function in African preschool children |
| title_sort | impact of early life exposures on lung function in african preschool children |
| topic | children preschool African |
| url | http://hdl.handle.net/11427/43406 |
| work_keys_str_mv | AT chayashaakira theimpactofearlylifeexposuresonlungfunctioninafricanpreschoolchildren AT chayashaakira impactofearlylifeexposuresonlungfunctioninafricanpreschoolchildren |