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Title:
Child-to-adult BMI trajectories in British birth cohorts: life course risk factors and adult health impacts.
Supervisors:
Leah Li and Simon Russell
Project Description:
Background:
The prevalence of obesity has increased worldwide in the past few decades. High body mass index (BMI) is associated with increased risk of numerous chronic diseases and poor general health. Therefore, how weight change at different windows of life may exert its adverse effect has critical implications, not only for understanding disease aetiology, but also for development of effective public health strategies and interventions. Furthermore, there may be specific life stages (i.e. sensitive periods) when risk factors have a greater effect on developing obesity and thus intervention for preventing/reducing obesity would be more effective.
Aims/Objectives: First, to explore life course BMI trajectories and identify patterns that are associated with adverse health outcomes. Second, to assess risk (or intermediate) factors at different life stages (i.e. fetal development, infancy, childhood, adolescence, and early, middle to late adulthood) for patterns of BMI trajectories. Third, to study the adverse health outcomes associated with specific BMI trajectories.
Methods:
The student will use data from three population-based UK birth cohorts born in 1958, 1970 and 2000-02. The 1958 British birth cohort (NCDS) included all babies born in one week, March 1958. Approximately 17,000 individuals were followed from birth, and at 7, 11, 16, 23, 33, 42, 46, 50, 55, and most recently at 62 years in 2020. BMI was available at all ages from 7 to 62 years.
The 1970 British birth cohort (BCS70) included all babies born in one week, March 1970. Approximately ~17,000 individuals were followed from birth, and at 5, 10, 16, 26, 30, 34, 42, 46, and most recently at 51 years in 2021. BMI was available from 10 to 51 years.
The Millennium Cohort Study (MCS) included children born in 2000-02 in the UK. A total of 18 818 infants were recuited at 9 months and followed up at 3, 5, 7, 11, 14, 17, and 23 years. BMI was available at all ages.
In each cohort, potential risk factors for obesity were collected at different life stages, including parental and prenatal factors (e.g. maternal and paternal BMI, parity, maternal smoking during pregnancy, maternal age at child birth, birthweight, gestational age), childhood factors (breastfeeding, sociodemographic factors, adverse childhood experiences, signs of puberty at 10/11y), and adult factors (socio-economic status, life styles). Outcomes could be general health, cardiovascular diseases risks, diabetes, mental health, disabilities, or other obesity-related outcomes.
The student may apply growth models and group mixture models to identify distinct patterns of BMI growth trajectories in each cohort, and to estimate the associations between risk factors and BMI trajectories. Conventional regression models or causal inferences may be used to explore associations between risk (or intermediate) factors for obesity, BMI trajectories and health outcomes.
References:
Li L, Hardy H (2015). Life-course BMI trajectories and blood pressure in mid-life in two British birth cohorts: stronger associations in the later-born generation. Int J Epidemiol, 44 (3), 1018-26.
Contact Information:
leah.li@ucl.ac.uk