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BMI trajectories from childhood to mid-to-late adulthood in two British birth cohorts

Project title 
BMI trajectories from childhood to mid-to-late adulthood in two British birth cohorts: life course risk factors and health impacts

Supervisors names
Leah Li
Simon Russell

Background:
The prevalence of obesity has increased worldwide in the past few decades. High body mass index (BMI) is associated with numerous chronic diseases (e.g. cardiovascular disease, diabetes, poor mental health, some forms of cancers). As the risk of these diseases increases with age, weight change over the life course may influence the disease risk. 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 distinct patterns of trajectories.
  • Third, to study the adverse health outcomes associated with specific BMI trajectories.

Methods: 
The student will use data from two large population-based UK birth cohorts born in 1958 and 1970. 

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. In both cohorts, potential risk factors for obesity were collected prospectively 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 cardiovascular diseases risks, diabetes, depression/anxiety, disabilities, mortality, 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.
  • Power C, Elliott J (2006). Cohort profile: 1958 British birth cohort (National Child Development Study). Int J Epidemiol 2006; 35(1): 34-41.
  • Sullivan A, Brown M et al (2022). Cohort Profile Update: The 1970 British Cohort Study (BCS70). Int J Epidemiol. 52(3): e179-e186


Contact
Leah Li (leah.li@ucl.ac.uk)