To date, there are no food frequency questionnaires that have been validated to assess nutrient intakes in pregnant women in Ireland. The present study aimed to assess the relative validity of a self-administered food frequency questionnaire during pregnancy.
The food frequency questionnaire was administered once during pregnancy between 12 and 34 weeks. Participants also completed a 3-day food diary during each trimester of pregnancy (reference method) and intakes from both the food frequency questionnaire and the mean of the 3-day food diaries were compared in a sample of 130 participants from the control arm of an intervention study.
Energy-adjusted Pearson's correlation coefficients ranged from 0.24 (riboflavin) to 0.59 (magnesium) and were all statistically significant (P < 0.05). The food frequency questionnaire tended to report higher energy and nutrient intakes compared to the food diaries. On average, 74% of participants were classified into the same ± 1 quartile and 7% into opposing quartiles by the two methods.
Overall, our food frequency questionnaire showed good relative validity. We conclude that a single administration of a food frequency questionnaire is a valid tool for ranking women in accordance with their nutrient intakes during pregnancy.