Work-family life courses and BMI trajectories in three British birth cohorts

M Kumari,S Bell,A Sacker,D Kuh,D Worts,P Mcdonough,R E Lacey,A Mcmunn

doi:10.1038/ijo.2016.197

Abstract

BACKGROUND/OBJECTIVES:Combining work and family responsibilities has previously been associated with improved health in mid-life, yet little is known about how these associations change over time (both biographical and historical) and whether this extends to body mass index (BMI) trajectories for British men and women. The purpose of this study was to investigate relationships between work-family life courses and BMI trajectories across adulthood (16–42 years) for men and women in three British birth cohorts.SUBJECTS/METHODS:Multiply imputed data from three nationally representative British birth cohorts were used—the MRC National Survey of Health and Development (NSHD; 1946 birth cohort, n=3012), the National Child Development Study (NCDS; 1958 birth cohort, n=9614) and the British Cohort Study (BCS; 1970 birth cohort, n=8140). A typology of work-family life course types was developed using multi-channel sequence analysis, linking annual information on work, partnerships and parenthood from 16 to 42 years. Work-family life courses were related to BMI trajectories using multi-level growth models. Analyses adjusted for indicators of prior health, birthweight, child BMI, educational attainment and socioeconomic position across the life course, and were stratified by gender and cohort.RESULTS:Work-family life courses characterised by earlier transitions to parenthood and weaker long-term links to employment were associated with greater increases in BMI across adulthood. Some of these differences, particularly for work-family groups, which are becoming increasingly non-normative, became more pronounced across cohorts (for example, increases in BMI between 16 and 42 years in long-term homemaking women: NSHD: 4.35 kg m–2, 95% confidence interval (CI): 3.44, 5.26; NCDS: 5.53 kg m–2, 95% CI: 5.18, 5.88; BCS: 6.69 kg m–2, 95% CI: 6.36, 7.02).CONCLUSIONS:Becoming a parent earlier and weaker long-term ties to employment are associated with greater increases in BMI across adulthood in British men and women.

Highlights

In the National Survey of Health and Development (NSHD), a very small group of men who made early transitions to parenthood (‘Teen parents’) experienced greater average increases in body mass index (BMI) than men with other work-family combinations
Mid-life BMI was higher among men who experienced a divorce (‘Work, divorced parent’ group; mean increase: 5.86 kg m–2, 95% confidence interval (CI): 5.16, 6.58)
Using prospective data from three British birth cohorts, we have shown that work-family life courses were related to differential growth in BMI across adulthood

Summary

Introduction

With a few exceptions,[1,2] combining paid work and family responsibilities has been shown to benefit health in mid-life.[3,4,5,6,7,8,9] Much of this work has focused on women, whose working lives are typically more entwined with caring responsibilities.[10,11] For instance, previous analyses of the Medical Research Council (MRC). British birth cohort) showed that women with relatively strong ties to employment and marriage had better health than women who spent long periods of time out of work looking after the home and family.[3] The timing of key life course transitions, such as becoming a parent, are likely to be important for subsequent health. This may be true for women—and all the more so when combined with weak ties to paid work and partnerships.[7,8]

Objectives

Methods

Results

Conclusion