- Title
- Maternal nutritional status and the respiratory health outcomes of high-risk offspring
- Creator
- Harvey, Soriah Matilda
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2022
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Wheeze and respiratory tract infections (RTIs) are common conditions during infancy and are more prevalent in infants born to mothers with asthma, making these infants high risk. Infant wheeze and RTIs are associated with increased healthcare utilisation, such as emergency department presentation, hospital admission and unscheduled physician visits, as well as higher medication use, public health costs, economic loss, and decreased quality of life for the child and family/carer. Wheeze during infancy has also been associated with an increased risk of chronic wheeze and asthma in school-aged children, as well as a reduction in respiratory ability and function. Available management, including pharmacological treatment, may reduce symptoms, but does not prevent the development of these conditions. Therefore, research aiming to identify key modifiable risk factors to inform prevention strategies, in an area where these strategies are lacking, is a public health priority. There is consensus that, for infants and children, a ‘window of opportunity’ exists in utero and in early life when environmental factors, including nutrition, may influence the risk of disease development more strongly than later periods of life. This thesis aims to examine modifiable nutritional risk factors during pregnancy and early life and their relationship with adverse respiratory outcomes, in high-risk offspring. This thesis focuses on two major nutritional factors: vitamin D and breastfeeding. Chapters 2 and 3 investigate maternal vitamin D in a prospective cohort of pregnant women with asthma. The determinants of vitamin D (25-hydroxyvitamin D) levels during pregnancy were explored, as well as the relationship between vitamin D levels at several time points during pregnancy on adverse respiratory outcomes in the offspring in the first six months of life. Vitamin D insufficiency was common during pregnancy in this cohort, and history of asthma exacerbation/s, having blood drawn in Winter or Spring and having a Non-European ethnicity were found to be determinants of lower vitamin D levels during pregnancy, with history of asthma exacerbation/s a novel determinant in pregnant women with asthma. This thesis found an 86% lower odds of recurrent wheeze in infants exposed to maternal vitamin D sufficiency in late gestation, indicating that late gestation vitamin D sufficiency may be important in protecting against poor infant respiratory health in the first six months of life. In Chapters 4 and 5, the impact of breastfeeding – a major source of early life nutrition - on infant wheeze and wheeze-related outcomes, is examined in high-risk infants by using a secondary analysis of two cohort studies, and by conducting a systematic review and meta-analysis. Wheeze was highly prevalent in infants born to women with asthma (52% of infants by 12 months of age) and breastfeeding (more than 6 months vs. never) significantly reduced the risk of wheeze and bronchiolitis by 46% and 52% within the first year of life, with lesser durations of breastfeeding (1-3 months, 4-6 months) also associated with lower wheeze-related healthcare utilisation in infancy, compared to no breastfeeding. Chapter 5, a systematic review and meta-analysis of 15 studies, found that infants with a family history of asthma/atopy who were breastfed were 32% less likely to wheeze during the first year of life; with this association even stronger in the first 6 months, with a 55% reduced odds. The research conducted as part of this thesis has contributed new information in the area of nutritional factors associated with infant respiratory illnesses. This research identified key factors to target for future prevention strategies among infants at high risk of wheeze and asthma development, such as the protective effect of late gestation vitamin D sufficiency, and provides novel longitudinal data to inform future research and the development and design of randomised controlled trials targeted to prevent these adverse infant outcomes from occurring. This thesis has shown that breastfeeding is protective to high-risk infant’s respiratory health and breastfeeding (duration and exclusivity) were lower than recommended for majority of the cohort, highlighting areas where future research should focus.
- Subject
- wheeze; asthma; maternal; infant; nutrition; vitamin D; breastmilk
- Identifier
- http://hdl.handle.net/1959.13/1513392
- Identifier
- uon:56716
- Rights
- Copyright 2022 Soriah Matilda Harvey
- Language
- eng
- Full Text
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