The Millennium Baby Study (as it was then known) set out to investigate several aspects of feeding and growth in infancy. These included:
- Weight loss in infants - what is 'normal'?
- How do early infant feeding patterns relate to breast feeding?
- When are babies weaned?
- How are appetite and weight gain linked?
To answer these questions we collected lots of information on the babies and their mothers using a special version of the Personal Child Health record, parent-completed questionnaires and health clinic measurements. The babies were weighed:
- Up to 8 times between birth and 13 months, and again at 30 months
Mothers answered questionnaires at birth, 6 weeks, 4 months, 8 months, 12 months, 30 months and 5-6 years covering:
- Feeding practices - breast and bottle feeding
- How often babies were fed and how long the feeds were
- Weaning ages and foods
- Food preferences
- General behaviour
- Mothers' eating patterns and personal characteristics
- Eating behaviour
- Repetitive behaviours
- Strengths and difficulties
What did we find?
It is well known that babies lose weight in the first few days after birth, but less is known about how much weight they lose and how much they then re-gain.
We found that:
- GMS babies lost less weight than shown in previous studies
- 4 in 5 babies regained their birth weight by 12 days old
- 26 babies lost more than 10% of their birth weight, but none showed signs of serious illness
- Babies who were lightest at birth lost the least weight
Feeding patterns and breast feeding
Information collected from feeding diaries and health checks showed that:
- Breast-fed babies were fed more often than bottle-fed or mixed-fed babies, but feeds lasted the same length of time
- Giving supplementary formula feeds was associated with stopping breast feeding by 6 weeks
When are babies weaned?
When the GMS babies were born the advice was that solids should not be introduced before 4 months of age (recommendations have since been increased to 6 months). We found that:
- Most babies were weaned between 3 and 4 months old
- Nearly one quarter of the babies started eating solids before 3 months old
- Only 10% of babies were weaned after 4 months
- Babies weaned before 3 months had increased risk of diarrhoea compared with those weaned after 4 months
Reasons for early weaning included fast weight gain by age 6 weeks, being bottle fed, and parent's perception that their baby was hungry.
Mother's influence on infant weight gain
We were interested to find out whether things in the mother's life (such as eating behaviour, mood and social characteristics) affected her baby's weight gain. We found that:
- Babies of mothers with post-natal depression had slower weight gain to age 4 months
- By the age of 12 months they were no different to the other children
Other characteristics had little effect on infant weight gain.
Mealtime energy intake and feeding behaviour
For this part of the study we filmed 87 children throughout two meals - 30 children who were not gaining weight as expected and 57 who had normal weight gain patterns. The films were used to identify different types of children's feeding behaviour, plus additional information such as energy intake, weight of food eaten and length of the meal.
We found that:
- There were no clear differences in feeding behaviour, however:
- Children with slow weight gain did eat fewer calories
- Children with slow weight gain were less likely to complete their meal sitting in a high chair