Early feeding of cows' milk in relation to growth and bone development in ALSPAC

The current guidelines on infant feeding state that cows'milk should not be given as the main milk drink to infants before the age of 12 months. Despite this in the latest infant feeding survey 6% of 9 month olds were being fed in this way. In ALSPAC when the CIF children were 8 months old diet records were provided for 1178 infants - 13% of these were having cows' milk as their only source of milk at this age and half of these were having more than 600 mg per day. In this group, in particular, the diet was much higher in energy, protein and fat than breast fed infants and there was evidence that these children grew faster up to 61 months of age. This group also had a very high calcium intake compared to the breast fed group and this might lead to greater bone density in later life. However we showed that levels of anaemia were high in the cows' milk fed infants and their intakes of many other nutrients were low. Therefore it is important to investigate further the long-term effects of early introduction of cows' milk in a longitudinal cohort.

Planned analysis

Using questionnaire data at 15 months we will devise feeding groups in relation to the early introduction of cows' milk. The groups identified will be mutually exclusive

1. Breast feeding at 6 month or beyond (reference category)

2. Cows' milk introduced by 6 months (breast feeding stopped before 6 months)

3. Cows' milk introduced between 7-12 months (breast feeding stopped before 6 months)

4. Cows' milk introduced at or after 12 months (breast feeding stopped before 6 months)

We will use CIF diet data at 8 months to verify that these questionnaire identified groups are likely to be associated with meaningful dietary differences in the way infants were fed.

We will investigate the following outcomes in relation to these milk groups:

Bone density at 9 and 11 years from DXA measurements made in focus clinics

Anthropometric measurements at 7, 9 and 11 years

Confounding variables such a sex of the child, parity, maternal smoking in pregnancy and education level will be included