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.

Validation of a FFQ for estimating ω-3, ω-6 and trans fatty acid intake during pregnancy using mature breast milk and food recalls.

BACKGROUND/OBJECTIVES: To assess the performance of a food frequency questionnaire (FFQ) for estimating ω-3, ω-6 and trans fatty acid intake during pregnancy. Moreover, we determined whether the fatty acid composition of mature breast milk represents a valuable biomarker for fatty acid intake during pregnancy. SUBJECTS/METHODS: A prospective study in 41 pregnant women, aged 18-35 years, was conducted. Food intake during pregnancy was evaluated by three 24-h recalls (24 hR), and 2 FFQ. The fatty acid composition of mature breast milk was determined by gas chromatography. The method of triads and joint classification between quartiles of intake were applied. RESULTS: The FFQ was accurate for estimating docosahexanoic (DHA), linoleic and total ω-6 fatty acids according to validity coefficients. Higher agreements (>70%) into the same or adjacent quartiles between the dietary methods were found for α-linolenic, total ω-3, linoleic and trans fatty acid intake. High validity coefficients for eicosapentanoic (EPA) and DHA acids of human milk were found (0.61 and 0.73, respectively), and the method was adequate for categorizing the intake of α-linolenic, total ω-3 and trans fatty acids compared with FFQ estimates, and for arachidonic acid and trans fatty acids compared with food recall estimates, during pregnancy. CONCLUSIONS: The FFQ was an accurate tool for categorizing α-linolenic, total ω-3 and trans fatty acid intake. According to the validity coefficients observed, the FFQ accurately estimated DHA, linoleic and total ω-6 fatty acids and the composition of mature breast milk was shown to be a suitable biomarker for EPA and DHA fatty acid intake during pregnancy.