The nutrition knowledge, attitudes and dietary behaviour of a group of women in early pregnancy and a group of non-pregnant women were compared to ascertain the impact of pregnancy on diet. The main results indicate that pregnant women do eat differently from non-pregnant women, in particular intakes of zinc and vitamin C, and the nutrient density of protein and sodium were higher and intakes of alcohol lower in the pregnancy group compared to the non-pregnant group. The group of pregnant women also tended to consume more milk and fruit and less chocolate, cakes and pastries compared to nonpregnant women. However, the differences in dietary behaviour between the two groups could not be accounted for by nutrition knowledge (the same in both groups). Higher scores for beliefs about ‘healthier eating’ and subjective norm were found in the early pregnancy group which might account for some of the observed differences between the groups. In addition, it is concluded that ‘historicity’ or a basic ‘knowledge’ of which foods to consume is prevalent in early pregnancy.