Primary and secondary outcomes are measured as detailed below.
Primary and secondary outcomes
Primary outcome is BMI sds-score and the secondary outcomes are PA, sedentary behaviour, motor function/development, sleeping habits, food intake, eating patterns and quality of life. These outcomes require repeated collection due to the rapid changes in height, weight, eating, motor development and PA behaviours in infants. They will therefore be measured at baseline (1 year of age) and yearly thereafter. For children in the intervention group, height, weight and waist circumference are measured every 6 month. Metabolic profile indicators, secondary outcomes, as reflected in biomarkers will be collected at the age of 1, 3 and 6.
Data on demography and socio-economic status is collected by self-report. Parent and infant data is collected by parental/carer self-completed questionnaires and objective measures (Table 1). The questionnaires include already existing validated questionnaires as well as additional questions developed by the Early STOPP project team for topics not reflected in the existing questionnaires. The questionnaires are completed by each parent separately at home before the annual visit. Together these questionnaires take between 30-45 minutes to complete.
Anthropometry and blood pressure
Trained staff members, using standard procedures and calibrated instruments, collect height, weight and waist-circumference on the infant and parents. Weight is measured with portable scales (Tanita HD-316, Tanita Corp.; Tokyo, Japan) to the nearest 0.1 kg, with shoes and heavy clothing removed. Height is measured to the nearest 0.1 cm using a fixed stadiometer. Based upon height and weight BMI is calculated. Waist circumference is measured right between the lower costal (rib) border and the iliac crest using a nonextensible tape. BMI and waist circumference sds-score will be calculated based upon age- and sex-specific reference values [25, 26]. Systolic and diastolic blood pressure (BP) are measured using an automated BP monitor (Dinamap model 8101, Critikon Inc.; Florida, USA) under standard conditions . All of these measurements take place in a private room.
Dietary intake and eating behaviour
A four-day estimated food diary, covering two weekdays and two weekend days, will assess the children's dietary intake. This diet assessment method is chosen since both qualitative and quantitative aspects of the children's diet intake will be evaluated . The parents' diet quality will be assessed using a semi-quantitative food frequency questionnaire (FFQ) developed and validated by the Swedish National Food Administration. To measure children's eating habits; the Children's Eating Behaviour Questionnaire (CEBQ) will be used . The CEBQ is a multi-dimensional, parent-report questionnaire aims to provide a useful measure of eating styles to study the early precursors of obesity and eating disorders. The CEBQ consists of 35 statements originally derived from interviews with parents about their children's eating behaviour and the literature on the subject. Originally the items covered eight dimensions (factors) of eating style: Food Responsiveness (FR), Emotional Over-Eating (EOE), Enjoyment of Food (EF), Desire to Drink (DD), Satiety Responsiveness (SR), Slowness in Eating (SE), Emotional Under-Eating (EUE) and Food Fussiness (FF).
Outcome measures from the food diary, FFQ and CEBQ will be energy and nutrient intake, meal patterns, times and quantity of vegetable and fruit intake as well snacking patterns.
Physical Activity, sedentary behaviour and motor function
Parents will report the frequency and duration in health related PA and sedentary behaviour during the previous week using the International Physical Activity Questionnaire (IPAQ), long version  at baseline. This is done to be able to compare with national PA data. When the children are 2, 3, 4, 5 and 6 years of age the parents will answer a question about their leisure time PA in the past 12 months . This is done to get a crude measure of the parent's PA levels over a year. Further, the parents will also report the number of hours their child typically spends playing outdoors on weekdays and weekend days. In addition, every year, parents and the child's PA and sedentary behaviour will be assessed objectively using the ActiGraph GT3X+ accelerometer (ActiGraph, LLC, Fort Walton Beach, FL). The ActiGraph has shown high agreement with energy expenditure and measures of time spent in different intensities for adults as well as for children 3 year and up [32–34]. A calibration study on children 2 years of age will be performed within the Early STOPP project. Outcome measures from the accelerometer will be total PA expressed as counts per minute, time spent in different intensities of PA as well as sedentary time. The families will get verbal and easy to read instructions from the research staff on how to wear the accelerometer (around the non-dominant wrist using an elasticated belt). The participants are asked to wear the accelerometer for seven consecutive days, but for the analysis we will include participants that have at least four days of measurements .
Motor function of the children will be assessed using the technique described by Hempel . The assessment is age specific and will take place when children are 2 and 4 years of age, respectively. The assessment takes about 30 minutes and will be videotaped to enable analysis afterwards. The examination focuses on motor-functions such as prehension, sitting, crawling, standing and walking behaviours, in a standardized free-field situation. The examination is based mainly on observation of spontaneous motor behaviour since observation is a suitable tool for assessment of qualitative aspects of motor function. The assessment results in three outcome measures; a fluency score, mainly considering fluency of movements (range 0-13); a Clinical classification with four categories ranging from normal to abnormal; a Neurological Optimality Score (range 0-58) . The inter-rater reliability of the Hempel assessment is satisfactory .
Assessment of children's and parents' day-to-day sleep pattern for weekdays and weekend at age 2 will be conducted and the ActiGraph GT3X+ accelerometer will be used. The ActiGraph provides an objective recording of sleep duration, sleep efficiency and sleep timing, and is a reasonable tool to evaluate how sleep varies on a day-to-day basis. ActiGraph has shown a good reliability compared with polysomnographic measures of sleep in adults [39, 40] and young persons [40, 41]. It is possible that the accelerometer does not discriminate entirely between sleep and motionless wakefulness, for example watching TV, which is why sleep diaries are preferred as a complement. For this purpose parents will be asked to complete the brief Infant Sleep Questionnaire (BISQ)  to assess children's sleep on a daily basis (7 days). The BISQ has been validated against accelerometry and daily-logs and its sensitivity in documenting expected developmental trends in young children's sleep and the effects of environmental factors have been established . Outcome measures are sleep duration and sleep efficiency (time in bed/sleep time), and settling times. Parents sleep pattern and sleep behaviour will be assessed with the Karolinska sleep/wake diary  and parents habitual sleep quality will be assessed with the Karolinska Sleep Quality Index (SQI) . The SQI has been validated against polysomnography and show good correlations with objective sleep parameters . Parenting stress will be assessed by Parenting Stress Index (PSI) , the Swedish version.
Fasting blood sample (50 ml for parents and 12 ml for child) is collected by a trained nurse from both parents and the child. The blood sample is analysed for inflammatory markers, cholesterol (total, HDL & LDL), triglycerides, insulin, glucose and hormones (leptin, ghrelin, adiponektin) using standard automated techniques at the KI laboratory. Parents are asked to provide a saliva sample at baseline and at follow-up at 3 and 6 years visits and stored in biobank, this will be used as a source of genomic DNA. Further, nitrate/nitrite levels will be measured in saliva and blood samples and correlated with blood pressure in both parents and their children. Saliva samples will be collected at the same time in tubes containing EDTA, with final concentration of 2 mM and stored at -80°C for later nitrate and nitrite determination. Samples will be analyzed by ion chromatography (ENO 20 Analyzer; Eicom, Kyoto, Japan). To assess the faecal bacterial flora, the microbiological samples will be taken from the stool and analyzed by using a highly parallel 454 Life Sciences GS20 pyrosequencer [47–49].