Child care link to obesity

"Indulgent grandparents 'overfeed' kids and make them fat," is the headline in the Daily Mail today.

The story is based on a large study looking at how different types of childcare between the ages of nine months and three years affect a child’s risk of being overweight. It found that grandparents provided three-quarters of all informal childcare, and that the children cared for full-time in informal care had a 34% increased risk of being overweight. This increased risk was limited to children from more advantaged socio-economic groups.

The results of this study are consistent with other research in the field. As the researchers suggest, promoting healthy options to grandparents providing childcare is potentially one way of preventing obesity and overweight in children. Exactly which aspect of weight management, physical activity, diet or both will need further assessment.

Where did the story come from?

This research was carried out by Dr A Pearce and colleagues from the Centre for Paediatric Epidemiology and Biostatistics at the UCL Institute of Child Health in London. The study was conducted as part of the Public Health Research Consortium supported by the Department of Health Policy Research Programme. Additional funding came from the Medical Research Council, a scheme of the National Institute for Health Research Biomedical Research Centres and grants made to the Millennium Cohort Study itself. The study was published in the peer-reviewed medical journal International Journal of Obesity .

Both the Daily Mail and BBC News highlighted the researcher’s suggestion that as National Insurance credits will soon be available to grandparents providing more than 20 hours a week care for grandchildren under 13 years, there is an opportunity for giving advice on healthy eating and exercise to grandparents.

What kind of research was this?

This was an analysis of data from a large cohort study in over 12,000 children. The participants had their height and weight measured and their parents or carers were interviewed at nine months and three years of age. The researchers analysed the data for links between type of childcare (formal, informal or parental) and the chance of the child becoming overweight or obese by age three.

The researchers explain that about 80% of three to six-year-olds and 25% of children under three are now in some form of early childhood education or childcare. They add that childcare is potentially a valuable setting for obesity prevention.

What did the research involve?

The researchers explain that childcare in OECD (Organisation for Economic Co-operation and Development) countries has recently been studied, as it was thought childcare might widen inequalities between different socio-economic groups. They say that although childcare offers a potential setting for obesity prevention, the association between childcare and children being overweight has not been adequately researched.

The researchers set out to investigate the links between childcare and becoming overweight (including becoming obese) particularly focusing on how the child’s socio-economic background affected this.

The researchers had data from 12,354 children in the UK who had been part of a cohort study called the Millennium Cohort Study. This study looked at children born in the UK between September 2000 and January 2002. Children were preferentially selected from disadvantaged areas, and areas with high proportions of ethnic minority groups so that the analysis of inequalities could be done.

Trained interviewers asked questions of the main caregiver, who was usually the mother, when the children were nine months old and again later when they were about three years old. In the first interview, mothers were asked whether they had breastfed and if so, how long for. Answers were categorised as 'never breastfed', 'breastfed for less than four months' and 'breastfed for four months or more'.

Measures of socio-economic background were based on both the household and area in which the child lived and were collapsed into three categories: managerial and professional, intermediate, and routine and manual occupations. Educational backgrounds were also assessed.

Of the original 18,296 singleton infants, 14,630 (80%) took part in the follow-up when the child was three. The children’s height and weight were measured at these times. Being overweight (including obesity) was defined by the International Obesity Task Force measures for body mass index (BMI).

Childcare was classified into three categories based on what care was used for the longest duration over the full three years, and was based on information given from the interviews:

  • Informal: care given by a friend, neighbour, grandparent or other relative, babysitter or unregistered childminder.
  • Formal: care given in a nursery or childcare centre or by a childminder (not reported as being unregistered), nanny or au pair.
  • Cared for only by a parent: children who had not been cared for by other means.

In total, there was complete childcare and height and weight data for 12,354 children. The researchers adjusted their results appropriately for other factors (confounders) that are known to affect infant and childhood weight, such as the mother’s weight before pregnancy, mother’s ethnicity, number of children living in the household, and smoking during pregnancy.

What were the basic results?

Between birth and four months of age, 6% of children had been in informal childcare for at least 10 hours a week and 2% had been in formal childcare.

By three years, nearly a quarter of the children had been in informal childcare since the nine-month questionnaire. Three-quarters of informal carers were grandparents. Just over one-fifth of children had been in formal childcare.

Approximately one-quarter of children were overweight or obese at three years old. After controlling for reasonable confounders, children who had been in informal childcare from the age of nine months to three years (75% of whom were cared for by grandparents) were more likely to be overweight than those cared for only by a parent (risk ratio [RR] 1.15, 95% confidence interval [CI] 1.04 to 1.27).

When looking at the socio-economic background of the parents, the increased risk of being overweight in informal childcare (compared with parental care) was limited to children from more advantaged groups, such as those whose mother was from a managerial or professional background (RR 1.23, 95% CI 1.02 to 1.47), had a degree (RR 1.43, 95% CI 1.13 to 1.83) or lived in a couple household (RR 1.18, 95% CI 1.06 to 1.32).

There was no association between formal childcare and being overweight. Differences in breastfeeding or the age the child was introduced to solids was not associated with overweight at age three years.

How did the researchers interpret the results?

The researchers say there is a greater risk that children from more advantaged families who are put in informal childcare will become overweight. They call for more health-related information and support for both informal and formal carers and say there is an opportunity for health promotion when grandparents claim National Insurance credits for caring for grandchildren.


This large well-designed study is one of only a few to comprehensively examine the potential for childcare in widening inequalities. It examined the link in relation to formal and informal types of childcare, including care by grandparents, using an objective measure of being overweight. The researchers mention a few minor limitations to their study:

  • The children were categorised to the type of childcare they mostly received based on answers given by their mothers at nine months and three years. It is possible that some recall inaccuracy was introduced at this point.
  • Mothers were not asked about diet or physical activity in either of the interviews. It is possible, if these varied by childcare type, that both of these factors could have influenced the results and explain the effect.

The results of this study are consistent with other research in the field and suggest a possible approach to preventing obesity and being overweight in children by focusing health promotion activities towards grandparents providing childcare. Exactly which aspect of weight management, physical activity, diet or both, should be the focus of any information campaign will need further assessment.

NHS Attribution