FAQs: About CLS research on children’s BMI and parents’ work

These FAQs provide additional information on the research covered in our news story ‘Children’s BMI tends to be higher in homes where both parents work, new study finds‘

Where can I read the scientific paper?

‘The impact of maternal employment on children’s weight: Evidence from the UK’, by Emla Fitzsimons and Benedetta Pongiglione was published in the open access scientific journal SSM – Population Health in November 2018. You can also read the news item on the CLS website.

Why did you carry out this particular study?

This study was motivated by two well-known recent empirical trends. The first is that the prevalence of childhood overweight and obesity has soared – the number of obese children and teenagers across the world has increased tenfold over the past four decades.[1] The second is that there has been a big increase in employment within families over this period, mainly as a result of increased participation of mothers in the labour market. This has resulted in a much higher proportion of two-parent earning families, and working single parent families than ever before. We were interested in understanding whether these two trends were in any way linked, and in particular whether changes in family employment may have played a role in increased childhood weight. There is very little evidence on this topic, and most of it is based on studies in the US.

Why might we expect parental employment to affect children’s weight?

Excess weight is caused by energy imbalance, such that more calories are consumed than expended. Increasing parental employment may affect children’s energy balance for a few reasons. On the one hand, increased employment leads to increased demands on parents’ time, and typically means that parents spend less time at home, with less time for meal preparation. Furthermore, the child will spend more time in the care of other family members and/or in childcare, which may have implications for choices concerning food intake and physical activity. On the other hand, increased employment results in higher family income, making healthier, more nutritious foods – typically more expensive than processed foods – more affordable. So a priori, it’s unclear how increased employment may affect children’s weight, making it all the more important to investigate it empirically using rich data and appropriate statistical methods.

What did you do in this particular study?

We examined the effect of parental employment on children’s weight using the UK Millennium Cohort Study (MCS), an ongoing longitudinal study following a representative sample of families born around the turn of the millennium in the UK. Families were first assessed when children were 9 months old, and have been followed up at ages 3, 5, 7, 11 and 14. Children have been weighed and measured by trained interviewers at each survey since the age of 3, providing an accurate measure of their body mass index (BMI). The study also contains detailed information on parental employment throughout childhood, alongside a wealth of other data such as on family structure, economic circumstances, educational development, mental and physical health, and health behaviours. Using rich data from around 8,000 participants, the research applies a sophisticated statistical methodology to unpick the role of parental employment from the wide range of other factors that can increase children’s weight. The method takes into account measured and unmeasured factors that may have increased children’s weight, with measured factors including family social background, income, ethnicity and health. It looks separately at the effect on children’s weight of mothers’ and fathers’ employment, and also compares single mothers to those in a couple.

What did you find?

We found that among couples, on average, children’s BMI was higher amongst households in which both parents work, compared to those where only the father works (the numbers were too small to compare to households where only the mother works). It also found that BMI was highest amongst children in single parent working households. Consistent with these findings, we also saw that children whose mothers were in employment were more likely to have increased sedentary behaviour, measured by watching TV three or more hours per day, and poorer dietary habits, measured by not having a regular breakfast.  Again, these effects were more pronounced among single mothers in employment.

What policy lessons do you draw from this study?

The findings from this research have several policy implications and need to be interpreted and transmitted cautiously. Given that female participation in the labour market has steadily increased over the last half century, and this is not expected to reverse, involving fathers as active players in efforts to tackle the high rates of childhood excess weight and to promote children’s health and wellbeing is a fundamental step. Programmes encouraging healthy behaviours among children could be better tailored to bring both parents on board, and to be accessible to all working parents including those with fathers and mothers working full-time, and to single working parents.  The other important stakeholders in childhood obesity prevention are those responsible for childcare, including in both informal and formal childcare settings, and schools. Preschool childcare settings are used by a growing number of families for extended periods each day, and hence will be increasingly central for promoting early healthy behaviours.

Could this research be interpreted as laying the blame on working mothers?

No. This research does not lay blame on working mothers, or indeed on anyone else. In recent decades we have seen large increases in female labour force participation, resulting in significantly more households with both parents working, as well as an increased number of households with single parents working. This places increased demands on parents’ time, and this study analyses whether this may have unintended adverse effects on children’s weight, for instance through affecting their nutritional intake and their levels of physical activity. Its aim is to provide robust evidence for policymakers to best support families to tackle concerns around childhood obesity in the UK today.

How important is parental employment compared to other factors?

The factors affecting children’s weight are complex and multi-dimensional, and have been studied extensively elsewhere. Whilst comparing findings across different studies can be challenging, it is important to bear in mind that parental employment is very likely to be only a small part of the explanation for increasing levels of child overweight and obesity across society as a whole.

Who can I contact for more information?

Meghan Rainsberry
m.rainsberry@ucl.ac.uk
0207 612 6530

Ryan Bradshaw
r.bradshaw@ucl.ac.uk
0207 612 6516

[1] NCD Risk Factor Collaboration 2017.