Cohort study on child health, lifestyles and weight status in the municipality of Sant Boi de Llobregat

Approved 25/10/2018, CEIm Fundació Sant Joan de Déu (C. de Sta. Rosa, 39, 08950 Barcelona, Esplugues de Llobregat, 08950, Spain; +34 (0)936009751; frecerca.ceic@sjd.es), ref: PIC-144-18

Measured at baseline and each follow-up every 3 years until adulthood. In the case of the quality of life variable, from the age of 9 years onwards, this variable will be collected through the same questionnaire, but it will be the children who will complete it.
1. Weight status: measured through weight (kg), height (m) and waist circumference (cm). Weight and height will be used to calculate the BMI (kg/m²) and zBMI. Weight and height will be collected with light clothing and without shoes. For waist circumference measurement, the participant will be asked to lift the t-shirt while being measured. The SECA 899 scale will be used to measure weight, with a 100 g precision. Height will be measured with the SECA 217 portable stadiometer to the nearest 1 mm. Waist circumference will be measured with the tape SECA 201 to the nearest 1 mm. All measurements will be performed by trained field researchers and ensure children's comfortability
2. Quality of life recorded using the 11-item KIDSCREEN10 questionnaire. Children's families will ask this scientifically validated questionnaire that includes 10 items about physical, psychological and social well-being. The 11th item corresponds to an overall question about children's health status.

The following children and adult variables will be collected through different questionnaires and this will be reported by the families at baseline and each follow-up every 3 years until the child’s adulthood. After 9 years of age, the children's variables will be collected through the same questionnaires, but they will be the children to complete them.
1. Children:
1.1. Adherence to the Mediterranean diet will be recorded by the 16 items of the KIDMED index questionnaire that enable a dichotomous answer (yes/no).
1.2. Physical activity will be assessed by the child's Physical Activity Unit - 7 items Screener (PAU-7S). An accelerometer (ActiGraph wGT3X-BT) will be worn during 9 days by a randomly selected 10% of the sample, to objectively measure physical activity and sleep data with the purpose of validating the questionnaire within 3-8-year-old children. This questionnaire was originally validated for children and adolescents aged 8-16 by our research group and the validation study is published elsewhere. The questionnaire collects the minutes of physical activity performed by the children during the week.
1.3. Sedentary behavior will be evaluated by the four-item Screen-time Sedentary Behavior Questionnaire (SSBQ). This questionnaire asks about the daily minutes of use of TV, computer/tablet, video games and smartphone during weekdays and weekends.
1.4. Sleep hours measured using four questions from the Sleep Survey for Adolescents questionnaire (SHSA). The questionnaire asks about the most common time to go to sleep and wake up on weekdays and weekend days in order to obtain total hours of sleep.
1.5. Additional indicators: gender, birth date, birth weight, birth country, number of years living in Spain, home address, number of adults (older than 18 years old) and children (minor than 18 years old) living in the household and breastfeeding. Additionally, they will be asked about the number of family meals per week and the weekly frequency of family physical activity during leisure time. The indicators birth date, birth weight, birth country and number of years living in Spain will be taken at the baseline only.

2. Parents:
2.1. Diet quality will be recorded by the four-question Short Diet Quality Screener Questionnaire (SDQS)
2.2. Physical activity and sedentary behavior will be assessed by the seven-item REGICOR short physical activity questionnaire
2.3. Sleep hours will be assessed using four questions from the Sleep Survey for Adolescents questionnaire (SHSA)
2.4. Self-perceived stress evaluated using the 10-item Perceived Stress Scale questionnaire (PSS)
2.5. Parental perception of the child's weight determined through one question of the questionnaire of the ALADINO study 2015. Parental feeding practices will be assessed by the 15 items from the Child Feeding Practice Questionnaire (CFQ). In the case of this variable, this will only be collected until the child is 12 years old.
2.6. Additional indicators: gender, weight, height, birth date, birth weight, birth country, number of years living in Spain, home address, educational level, occupation and labour market status, annual home income and smoking habit