Reproducibility and validity of a food frequency questionnaire among pregnant women in a Mediterranean area
1 Departamento de Salud Pública, Universidad Miguel Hernández, Ctra. Nacional 332 s/n 03550, Campus San Juan de Alicante, Spain
2 CIBER en Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain
3 Unidad de Vitaminas. Servicio de Bioquímica Clínica Hospital Universitario Puerta de Hierro-Majadahonda Edificio Laboratorios (Peine 7), Planta 1ª c/Maestro Rodrigo, 2 28222, Madrid, Spain
4 Centre for Public Health, School of Medicine, Dentistry and Biomedical Sciences, Queen’s University Belfast, Belfast, UK
5 Dirección General de Salud Pública, Consejería de Sanidad, Avda Catalunya 21, 46020, Valencia, Spain
6 Centro Superior de Investigación en Salud Pública (CSISP), Consejería de Sanidad, Avda Catalunya 21, 46020, Valencia, Spain
7 University of Valencia, Valencia, Spain
Nutrition Journal 2013, 12:26 doi:10.1186/1475-2891-12-26Published: 19 February 2013
Studies exploring the role of diet during pregnancy are still scarce, in part due to the complexity of measuring diet and to the lack of valid instruments. The aim of this study was to examine the reproducibility and validity (against biochemical biomarkers) of a semi-quantitative food frequency questionnaire (FFQ) in pregnant women.
Participants were 740 pregnant women from a population-based birth cohort study in Valencia (INMA Study). We compared nutrient and food intakes from FFQs estimated for two periods of pregnancy (reproducibility), and compared energy-adjusted intake of several carotenoids, folate, vitamin B12, vitamin C and α-tocopherol of the FFQ in the first trimester with their concentration in blood specimens (validity).
Significant correlations for reproducibility were found for major food groups and nutrients but not for lycopene (r=0.06); the average correlation coefficients for daily intake were 0.51 for food groups and 0.61 for nutrients. For validity, statistically significant correlations were observed for vitamin C (0.18), α-carotene (0.32), β-carotene (0.22), lutein-zeaxantin (0.29) and β-cryptoxantin(0.26); non-significant correlations were observed for retinol, lycopene, α-tocopherol, vitamin B12 and folate (r≤0.12). When dietary supplement use was considered, correlations were substantially improved for folate (0.53) and to a lesser extent for vitamin B12 (0.12) and vitamin C (0.20).
This study supports that the FFQ has a good reproducibility for nutrient and food intake, and can provide a valid estimate of several important nutrients during pregnancy.