Non-linear relationship between maternal work hours and child body weight: Evidence from the Western Australian Pregnancy Cohort (Raine) Study

Abstract

Using longitudinal data from the Western Australia Pregnancy Cohort (Raine) Study and both random-effects and fixed-effects models, this study examined the connection between maternal work hours and child overweight or obesity. Following children in two-parent families from early childhood to early adolescence, multivariate analyses revealed a non-linear and developmentally dynamic relationship. Among preschool children (ages 2 to 5), we found lower likelihood of child overweight and obesity when mothers worked 24 h or less per week, compared to when mothers worked 35 or more hours. This effect was stronger in low-to-medium income families. For older children (ages 8 to 14), compared to working 35-40 h a week, working shorter hours (1-24, 25-34) or longer hours (41 or more) was both associated with increases in child overweight and obesity. These non-linear effects were more pronounced in low-to-medium income families, particularly when fathers also worked long hours.

Maternal Employment and Infant BMI z Score in a US Birth Cohort

“…Our study investigated the association during infancy, whereas prior US studies investigated the association among older-aged children. Several studies suggest that the association may differ by child age (12,13,17,22), and our findings generally supported this hypothesis. Our sample was lower income and had a lower level of educational attainment compared with prior studies and national averages.…”

“…These findings are generally consistent with US studies, which have reported that additional hours of maternal work increase the probability of childhood overweight/obesity (7,9,14). In an Australian sample, a larger magnitude of effect was observed among lower-income families (13) in contrast with results from Germany (12) and the United States (5,7-10), where larger effects were observed among higher-income families.…”

“…Prior studies have suggested that maternal employment is associated with a higher BMI among children (5)(6)(7)(8)(9)(10) and that it has contributed to 10% of the growth in childhood overweight over the past few decades in the United States (11). However, studies have reported differential effects by the number of maternal work hours, socioeconomic status, and child age (5,(7)(8)(9)12,13). For example, Li and colleagues reported a lower likelihood of overweight/obesity among preschool-aged children when mothers in Western Australia worked ≤24 hours per week compared with mothers who worked ≥35 hours (13).…”

Long work hours of mothers and fathers are linked to increased risk for overweight and obesity among preschool children: longitudinal evidence from Germany

“…Li and coauthors1 found that the effect of maternal long work hours on child overweight and obesity strengthened when fathers worked 45 hours or more per week in an Australian cohort. We examined three different definitions of fathers’ long work hours (≥45, ≥50 and ≥55), and there appeared an increasing trend in effects of maternal work hours as the threshold of fathers’ long work hours rose.…”

“…This co-occurrence has drawn much research attention to the link between the two trends 1. The vast majority of existing studies2–10 focused on US children.…”