Validation of a food frequency questionnaire to assess food group intake by pregnant women.

BACKGROUND: Previous studies conducted among pregnant women to test the accuracy of food frequency questionnaires (FFQ) for estimating food group intake were restricted to one specific trimester of pregnancy. The present study aimed to validate a FFQ for assessing the intake of food groups throughout pregnancy.

METHODS: In total, 75 adult pregnant Brazilian women were evaluated. Dietary intake was assessed by the FFQ (completed at the third trimester of pregnancy) and by three 24-h dietary recalls; one in each trimester of pregnancy.

RESULTS: The food items were classified into 20 groups. Adequate deatenuatted Pearson correlation coefficients (>0.4) were observed for the intake of bread/cake, butter/margarine; milk/dairy products; soft drinks/artificial juices; coffee/tea; and pastries/sandwiches. The FFQ served poorly for estimating fruit and vegetable intake. A high percentage (>70%) of women were classified into the same or adjacent quartiles for estimates of cookies/crackers, butter/margarine, milk/dairy products, fruit juices, soft drinks/artificial juices, coffee/tea, roots, rice, beans, meat/chicken/sausages, fried foods, fish, eggs, sweets/sugars, and pastries/sandwiches. Nevertheless, the agreement of joint classification between the dietary methods was mostly into adjacent quartiles, rather than in the same quartile, and low values of kappa were found.

CONCLUSIONS: The data reported in the present study suggest that the FFQ might not be an appropriate dietary method for evaluating food group intake throughout pregnancy. The joint classification between methods by categories of intake of food groups was mostly into adjacent quartiles, which could lead to attenuated associations when investigating diet-disease relationships during pregnancy.