Dietary patterns in pregnancy and associations with socio-demographic and lifestyle factors.

To obtain distinct dietary patterns in the third trimester of pregnancy using principal components analysis (PCA); to determine associations with socio-demographic and lifestyle factors. A total of 12 053 pregnant women partaking in a population-based cohort study recorded current frequency of food consumption via questionnaire in 1991-1992. Dietary patterns identified using PCA were related to social and demographic characteristics and lifestyle factors. Five dietary patterns were established and labelled to best describe the types of diet being consumed in pregnancy. The 'health conscious' component described a diet based on salad, fruit, rice, pasta, breakfast cereals, fish, eggs, pulses, fruit juices, white meat and non-white bread. The 'traditional' component loaded highly on all types of vegetables, red meat and poultry. The 'processed' component was associated with high-fat processed foods. The 'confectionery' component was characterized by snack foods with high sugar content and the final 'vegetarian' component loaded highly on meat substitutes, pulses, nuts and herbal tea and high negative loadings were seen with red meat and poultry. There were strong associations between various socio-demographic variables and all dietary components; in particular, a 'health conscious' diet was positively associated with increasing education and age and non-white women. There was a negative association with increased parity, single, non-working women, those who smoked and who were overweight pre-pregnancy. Opposite associations were seen with the 'processed' component. Distinct dietary patterns in pregnancy have been identified. There is clear evidence of social patterning associated with the dietary patterns, these social factors need to be accounted for in future studies using dietary patterns. This study will form the basis for further work investigating pregnancy outcome.