Learn more about the Millennium Cohort Study (MCS) and its dietary measurements
Summary of study
The Millennium Cohort study (MCS), also known as ‘Child of the New Century’ is the youngest of the UK’s birth cohort studies. MCS is a study of all children born between September 2000 and January 2002 in 398 areas across England, Scotland, Wales and Northern Ireland who were alive and living in the UK at 9 months and eligible to receive child benefit . The original sample consisted of 18,552 families (18,827 children). In 2003-2004 during the survey at age three (MCS2), the sample was boosted by families in England who were eligible for inclusion in MCS1 but were missed. The boost brought the total number of children taking part to 19,517 . A stratified cluster sampling framework was used to adequately represent families from disadvantaged areas and ethnic minority groups.
There have been six data collections to date: 9 months, 3, 5, 7, 11 and 14 years. The 17 year data collection was completed in 2019, with the data being made available in mid-to-late 2020. A range of social, economic, demographic and health information have been collected and the data have been linked to administrative data resources.
Dietary data collection
Information about infant feeding was collected at 9 months (2001), 3 (2004) and 5 (2006) years. Additional information about the children’s diets were collected at 5, 7 (2008), 11 (2012) and 14 (2015) years. The main caregiver answered questions on behalf of the child up to age 11. The child themselves responded to the questions at 14 years. All questions were asked during a computer assisted personal interviewing questionnaire (CAPI) during a home visit.
At 9 months, the main caregiver provided information on aspects of infant feeding including breastfeeding and/or formula duration, other types of milk consumed and the introduction of solid foods (questionnaire can be found at: https://cls.ucl.ac.uk/wp-content/uploads/2017/07/MCS1_CAPI_Questionnaire_Documentation_March_2006_v1.1.pdf).
At 3 and 5 years, the main caregiver confirmed whether the baby was still breastfeeding and/or the age at which they last had breast milk.
At ages 3, 5, 7, 11 and 14 years, while no established DAT was used, the frequency of consumption of a limited number of specific foods was recorded and these foods varied across sweeps (see the table below).
|Age 3y||Age 5y||Age 7y||Age 11y||Age 14y|
|Does the child eat a portion of fresh fruit or vegetables daily||✔|
|How many portions of fresh, frozen tinned or dried fruit consumed per day||✔||✔||✔|
|Frequency of at least 2 portions of fruit per day (not including fruit juices)||✔|
|Frequency of at least 2 portions of vegetables including salad, fresh, frozen or tinned vegetables per day||✔|
|What type of milk is normally used**||✔|
|What type of bread is normally eaten†||✔|
|Frequency of breakfast consumption||✔||✔||✔||✔|
|If the child eats between meals, what do they usually eat‡||✔||✔|
|When the child drinks between meals, what do they usually drink§||✔||✔|
|How often does the child drink sweetened drinks||✔||✔|
|How often does the child drink artificially sweetened drinks||✔||✔|
|How often, if at all do they eat fast food||✔|
|Do parents control the diet for specific reasons e.g. allergy, vegetarian, weight control, religion||✔||✔|
|Midday meal provided by school? Free/Paid for?||✔||✔||✔|
* Link provided to CLOSER Discovery (interactive version) or original study PDF as applicable.
** Only whole milk/ sometimes whole milk, sometimes semi-skimmed or skimmed milk/ only semi-skimmed milk; sometimes have semi-skimmed, sometimes I have skimmed milk/ only have skimmed milk/ only 1% fat milk/ soya milk or other non-cow milk/ never have milk.
† White bread only/sometimes white, sometimes brown or granary or wholemeal bread (including 50:50 bread)/ only brown/granary bread (including 50:50 bread)/ sometimes brown/granary bread (including 50:50 bread), sometimes wholemeal bread/ only wholemeal bread/ never eat bread.
‡ Crisps and other similar snacks/Breakfast cereal/Cakes and sweet biscuits/Fruit (fresh, dried or tinned)/Vegetables (raw or tinned)/Bread, toast and similar items e.g. crumpets, muffins/Crispbread, crackers, breadsticks, rice cakes etc/Sweets or chocolate/Yoghurt, fromage frais etc./Other dairy products like cheese or eggs /Other (specify)/Does not eat between meals.
§ Sweetened drinks (e.g. cola, squash, sunny delight)/Artificially sweetened drinks (diet cola, sugar-free squash)/Unsweetened or pure fruit juice/Water/Hot drinks (e.g. tea or coffee)/Milk/Milkshakes, hot chocolate and other drinks made with milk/Other.
The table below provides the response to dietary questions in MCS. The original cohort consisted of 18,827 children.
Response to dietary measures in MCS
|Year||Age (y)||N interviewed||Response to diet question* (n(%))|
|2001||9 months||18,552||18,527 (99%)†|
|2004||3 y||15,590||15,445 (99%)‡|
|2006||5 y||15,246||15,168 (99%)|
|2008||7 y||13,857||13,782 (99%)|
|2012||11 y||13,469||13,354 (99%)|
|2015||14 y||11,884||11,498 (97%)|
* Response based on answering at least one of the questions from the questions listed above.
† Based on information about breastfeeding, formula and cow’s milk.
‡ Based on information about daily consumption of fruit and vegetables.
The few papers to date using the dietary data of MCS have focused on infant feeding. Mothers who were in full-time employment and those who returned to work within four months of having their baby were less likely to initiate breastfeeding  as were younger mothers of white ethnicity, low levels of education and those in disadvantaged communities . Breastfeeding was found to be associated with a reduced risk of hospitalisations (for diarrhoea or lower respiratory tract infections) as well as with higher measures of cognitive ability at 3, 5, and 7 years [138, 139]. Infants who did not receive breast milk gained weight faster between birth and 3 years than those who did breastfeed . Similarly, infants who were never breastfed and those who were introduced to solid foods before four months old were more likely to be overweight by three years .
Continuing on the theme of risk factors for overweight in childhood, researchers observed that children who had an early introduction to solid foods, fewer portions of fruit per day, who did not regularly eat breakfast and who ate at irregular times were also more likely to be obese at 5 years . Being in the lowest quintile (vs. highest) for family income was associated with being obese at 5 years and diet (skipping breakfast, fruit consumption and sugar-sweetened beverage consumption) explained part of this inequality . Maternal employment was associated with dietary differences among children at 5 years: children of mothers who worked full time were more likely to drink sweetened beverages between meals, less likely to eat fruit or vegetables as a snack or achieve three of more portions of fruit per day at 5 years .
Learn about the other studies covered by this guide and their dietary measurements:
- Overview of dietary information in selected CLOSER studies
- Hertfordshire Cohort Study (HCS)
- 1946 National Survey for Health and Development (NSHD)
- 1958 National Child Development Study (NCDS)
- 1970 British Cohort Study (BCS70)
- Understanding Society: The UK Household Longitudinal Study (UKHLS)
- The Avon Longitudinal Study of Parents and Children (ALSPAC)
- Southampton Women’s Survey (SWS)
Get background detail on this guide:
- Objective and outline of this guide
- Dietary research in context
- Dietary assessment tools (DATs)
- Estimating nutrient intakes from DATs
Learn about harmonisation in the context of dietary data:
- Acknowledgements and copyright information for this guide
- References for this guide
- Download the full guide as a PDF
This page is part of the CLOSER resource: ‘A guide to the dietary data in eight CLOSER studies’.