Reproducibility and Relative Validity of a Short Food Frequency Questionnaire for Chinese Pregnant Women in Hong Kong

Research Article

Austin J Nutri Food Sci. 2020; 8(3): 1146.

Reproducibility and Relative Validity of a Short Food Frequency Questionnaire for Chinese Pregnant Women in Hong Kong

Kenneth Lo1, Liz Li2, Jason Leung3, WH Tam4 and Ruth Chan1*

1Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China

2Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Shatin, Hong Kong

3Jockey Club Centre for Osteoporosis Care and Control, The Chinese University of Hong Kong, Shatin, Hong Kong

4Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Shatin, Hong Kong

*Corresponding author: Ruth Chan, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China

Received: September 29, 2020; Accepted: October 21, 2020; Published: October 28, 2020


Food Frequency Questionnaire (FFQ) should be tailored and shown to be reliable and valid for use in a specific population. Therefore, we developed a short Food Frequency Questionnaire (FFQ) for Chinese pregnant women in Hong Kong and evaluated its reproducibility and validity. We recruited 45 pregnant women from a hospital or maternal and child health centers during 29 November 2018 to 14 November 2019, then the short FFQ was administered twice in one month. Three-day Dietary Recalls (DR) were conducted between two FFQ administrations. Reliability of dietary intake was evaluated by Intraclass Correlation Coefficient (ICC), and the relationship between FFQ- and DR-reported values was examined using Pearson correlation. The reliability of nutrient intake was moderate (0.50 to 0.75) to good (0.75 to 0.90), but only poor (<0.5) to moderate for food group intake. Most nutrients reported by the short FFQ significantly correlated with values reported by dietary recalls. Meanwhile, only several food groups showed significant correlations in the values reported by short FFQ and dietary recalls. When looking across nutrient and food group categories, it is notable that fiber and fruit intake have demonstrated good reliability and validity. To conclude, our short FFQ can serve as a quick assessment tool to identify pregnant women with unhealthy diet in community level and is particularly useful to classify individuals with low fruits or fiber intake.

Keywords: Food Frequency Questionnaire; Dietary Recall; Pregnant Women; Reliability; Validation Study; Asian Diet


DR: Dietary Recall; FFQ: Food Frequency Questionnaire; GDM: Gestational Diabetes Mellitus; ICC: Intra-Class Correlation Coefficient; MCHC: Maternal and Child Health Center


Optimal maternal nutrition is important for long-term health of both mother and offspring. Over-nutrition during pregnancy leads to maternal obesity and is of global public health concern [1,2]. Adverse in utero environment increases the risk of childhood obesity and associated disorders, through the foetal programming [3]. Evidence from animal and human studies shows that foetus exposed to excess nutrient supply before birth is associated with an increased risk of obesity and associated metabolic disorders in later life [2,4]. Moreover, maternal Gestational Diabetes Mellitus (GDM) and gestational weight gain increased the offspring’s cardiometabolic risk [5,6]. Taken together, maternal dietary habits during pregnancy should be carefully monitored to prevent adverse health consequences for mothers and children.

In Hong Kong, the prevalence of GDM is raising from 14.2% in early 90s to 32.5% in 2014 [7,8], which is alongside with the rising epidemic of obesity and diabetes in Hong Kong in the past decades [9]. Although the importance of maternal nutrition on mother’s and offspring’s health is highly recognized, there is no brief and validated dietary assessment tool available for Hong Kong pregnant women. One of the commonly used tools for dietary assessments would be Food Frequency Questionnaire (FFQ), especially for large-scale epidemiological studies [10]. FFQ is a valid and reliable tool for assessing nutrient or food intakes for pregnant women in different countries including China [11-13].

Since dietary habits vary greatly in population with different regional, ethnic, or cultural backgrounds, the FFQ should be tailored and validated for use in a specific population. Moreover, food frequency questionnaire usually contains >100 items [14], which may become a burden for pregnant women during administration. Therefore, we have developed a short FFQ with 50 items and have tailored for the dietary habits of Hong Kong pregnant women, which is a mix of Westernized and Chinese diet. In this study, we evaluated the reproducibility and relative validity of this short FFQ to assess food group consumption and nutrient intake for Chinese pregnant women in Hong Kong.

Materials and Methods

Study Design and Participants

Participants were pregnant women attending the antenatal clinic of the Prince of Wales Hospital or Maternal and Child Health Centers (MCHCs) in Hong Kong and being recruited using convenience sampling. Participants were interviewed by a trained research staff for dietary assessment and questionnaire completion after their written consent. The study protocol was performed in compliance with the Declaration of Helsinki and approved by the Clinical Research Ethics Committee of The Chinese University of Hong Kong (CREC Ref. No.: 2018.440) and the Ethics Committee of the Department of Health in Hong Kong (LM 29/2019).

Participants were eligible if they fulfill the following criteria.

Inclusion criteria:

1. Hong Kong Chinese citizen

2. Reside in Hong Kong

3. Age at or above 18 years old

4. With antenatal registry in Prince of Wales Hospital MCHCs

5. Singleton pregnancy

6. Could speak and understand Chinese

7. Willing to follow the study procedures.

Exclusion criteria:

1. Currently participating in any clinical trial or trial with dietary intervention

2. Multiple pregnancy

3. With any renal, liver, or thyroid dysfunction, any other indication of a major medical or psychological illness, as judged by the investigators as ineligible to participate the study.

Data Collection

Maternal information was collected using questionnaires and retrieved from the hospital or clinic record. Physical examination measurements of participants included weight and height, which was measured using electronic scales and stadiometer, and prepregnancy weight was self-reported. Demographic characteristics, including mother’s age, education, occupation, family income, and smoking status were collected using a standardized questionnaire and retrieved from the hospital/clinic record.

Dietary Assessments

Dietary intake was assessed by two dietary assessment methods, including three 24-hour dietary recalls and a newly developed Food Frequency Questionnaire (FFQ). The 50-item FFQ was newly developed by clinical experience from a panel of dietitians, nutritionists, nurses and doctors, and with reference to a FFQ available for the local adult population [15], as well as other FFQs for pregnant women from the literature [11-13]. Each participant was asked to complete FFQ twice within 3 to 4 weeks interval (for reproducibility evaluation), and three 24-hour dietary recalls in between the two administrations of the FFQ as a reference method to validate the FFQ (for validity evaluation). The three 24-hour dietary recalls included two weekdays and one weekend day.

On the interview day in which the 1st FFQ was administrated (FFQ1), each participant was explained by trained research staff on how to complete the FFQ by herself with the provision of the food portion booklet. Each participant was asked to complete the 1st FFQ regarding her intake of various food groups over the past month. The frequency of food group intake was reported per day, week or month, and portions were reported based on standard referent portion sizes, as pieces, glasses, cups, spoons, milliliters, or grams. On the same interview day, participant was also asked by trained research staff to recall all foods and beverages that have been consumed over the past 24 hours. Food photo albums and eating utensils of standardized portions were displayed to help recall. The 2nd administration of the FFQ (FFQ2) was done 3 to 4 weeks after the 1st administration of the FFQ. The FFQ2 and the food portion booklet as well as the additional 24-hour recall forms were given to the participants by email, smart phone messages or post within 3 to 4 weeks after the 1st administration of the FFQ (FFQ1). Between the intervals of two FFQs, the research staff gave phone call or smart phone messages to the participant on two separate days to complete two more 24- hour dietary recalls for validity evaluation purpose. Daily dietary and nutrient intake collected by both FFQs and 24-hour recalls were entered and calculated using the nutrition analysis software Food Processor Nutrition analysis and Fitness software version 8.0 (ESHA Research, Salem, USA) including local foods selected from food composition tables from China and Hong Kong.

Statistical Analysis

Continuous variables were presented as mean (standard deviations) for parametric data and as median (interquartile range) for nonparametric data. Categorical variables were presented as number (percentage). Intra-class correlation coefficients (ICC) were calculated to examine the reproducibility between FFQ1 and FFQ2. Based on the reported ICC, the reliability of dietary intake can be categorized into poor (<0.5), moderate (0.5 to 0.75), good (0.75 to 0.90) and excellent (>0.90) respectively [16].

Pearson’s correlations were used to validate results of FFQ1 against the average of three 24-hour recalls. As an alternative analysis, we applied energy adjustment using the residual method of Willett [17], and computed the Pearson correlation using the energy-adjusted nutrient and food group intake. Differences in nutrient and food group intakes between the first FFQ and the average of three 24-hour recalls were examined using one-sample t-test. We also examined if the differences in nutrient and food group intakes between the first FFQ and the average of three 24-hour recalls increased with the average of FFQ1 and 24-hour recalls, with the use of linear regression. A quartile classification analysis was used to categorize the nutrient intake and food group intake calculated from the FFQ and the three 24-hour recalls. Below is the list of categories of nutrient and food group intake.

Category of nutrient intake: energy; protein; carbohydrates; fibre; total sugar; total fat; saturated fat; trans-fat; cholesterol; % energy from protein; % energy from carbohydrates; % energy from total fat, % energy from saturated fat; vitamin C; calcium; iron; magnesium; phosphorus; potassium; sodium; zinc

Category of food group intake: condiment; grains; fruits; vegetables; meat, poultry, processed and organ meat; fish and sea foods; eggs; dairy and dairy products; beverages; tea or coffee; soy and soy products; legumes; nuts and seeds; sugary snacks; water; fast food; savory snacks; dim sum (Chinese cuisine of small dishes); oil.

In addition, the percentage of correctly classified subjects into the same, adjacent (±1 quartile) or extreme quintiles (±3 quartiles) were calculated. Lastly, for nutrients or food groups with at least moderate reliability and validity, Bland-Altman plots were performed to visually present the agreement between the first FFQ and three 24-hour recalls. All statistical analyses were performed using the statistical package SPSS version 24.0 (SPSS Inc., Illinois, US). All statistical tests were two-tailed, and significance were set at p < 0.05.


Demographic Characteristics

Table 1 presents the demographic characteristics of 45 participating women. The average age was 32.0-year-old, and the gestational week was 25.4 on average. Out of 45 participants, 60% were first-time mothers. A total of 66.7% participants were overweight or obese before pregnancy, 44.4% of them received tertiary education, 91.1% of them were married. Around half of the participants (51.1%) were working, and 56.8% of them earnt HK$20,000 (approximately USD$2500) or above per month. There were 6.7% of mothers have consumed cigarettes.