Behavioral counseling to prevent childhood obesity – study protocol of a pragmatic trial in maternity and child health care

The primary aim is to evaluate whether a multifaceted structured lifestyle intervention in primary care setting has potential to prevent overweight among preschool children belonging to a risk group. Additional aims include assessing changes in metabolic profile, waist circumference, blood pressure, dietary habits and time spent physically active, sleep and screen time of the offspring.

Participant intervention group mothers at risk of gestational diabetes gain less excess weight and have better glucose tolerance during pregnancy via intensified counseling on healthier diet and physical activity. These goals are expected to favour normal offspring weight development. Continued counseling in child health care clinics concerning age-appropriate diet, physical activity, sedentary behaviour and sleep pattern is expected to further diminish offspring’s risk for obesity.

The study (VACOPP Study = VAasa Childhood Obesity Primary Prevention Study) is non-randomized controlled clinical pragmatic trial. The setting is eight municipal maternity and 14 child health care clinics in city of Vaasa in western Finland. All maternity and child health care clinics in the city participated in recruiting and intervention. The cohort of mothers who gave birth year 2008 and had risk factors for developing GDM and their offspring were the targets for recruiting the control group. Mothers pregnant during 2009–2010 with the same risk factors were targetted for the intervention group. The control group mothers were recruited retrospective, before their children had reached one year of age. Ethical approval for the study was granted by the Ethics Committee of Vaasa Hospital District.

Informed written consent was provided by all participant mothers prior baseline assessments. The participants were mothers living in the city of Vaasa and belonged to a risk group for developing GDM. Criteria for belonging to this risk group were body mass index (BMI) ≥ 25 kg/m², macrosomic newborn (weight ≥ 4500 g) in any previous pregnancy, immediate family history of diabetes and/or age ≥ 40 years. This group of mothers are offered oral glucose tolerance test (OGTT) during pregnancy by the municipal maternity care. The offspring of these mothers are the target children. The exclusion criteria for the mothers were: multiple pregnancies, inability to speak Finnish, substance abuse or psychiatric illness fundamentally affecting ability to function. Recruitment of the control group was performed via telephone calls by a research nurse asking permission to send written research information and consent forms to subjects’ homes. The intervention group recruitment took place in maternity clinics by public health nurses (PHN) at first contact. PHN gave the written research information and consent form. All mothers recruited were offered an opportunity to ask questions concerning the trial by telephone or e-mail of either the research nurse or the researchers. Since the study was a pragmatic trial, power calculations were not given priority. Due to the small number of expected participating mothers and retrospective control group the study would not reach statistical significance in a rigorous sense. The mean BMI z-score in the control group would be only a rough estimate thus making power calculations inaccurate [22].

The intervention started in the maternity clinics and continues in child health care clinics until the child is five years old. The intervention is intensified multifaceted lifestyle counselling. The intervention group mothers were offered two group counseling sessions: one during both first and second trimester of pregnancy. 1.5 hour sessions were given by a trained physiotherapist and dietician employed in public health centre. Information on diet was according to the nutrition recommendations of Ministry of Social Affairs and Health during pregnancy especially concerning appropriate energy content, fibre, quality of carbohydrates and fat [23]. The physiotherapist gave information about suitable and sufficient amount of exercise during pregnancy [24], and the mothers participated in brief session of gymnastics suitable to do at home. The mothers also received information on the effect of healthy diet, exercise and appropriate weight gain during pregnancy on risk of having GDM, offspring’s perinatal problems and obesity risk. Written educational material on healthy diet and physical activity during pregnancy was also given. This counseling was repeated more briefly by the PHNs during 13 routine visits to maternity clinics. After delivery the mothers were given a written information leaflet by a PHN reminding them that breastfeeding up to 6 months of age is also recommended for appropriate weight gain of the infant.

The families are offered to participate a 1.5 hour structured group counseling session when the child is 1 to 2 years old. It is given by physiotherapist and dietician employed in health care center and includes healthy diet recommendations to children under school age [23], as well as advice on suitable physical exercise at that age. The physical activity recommendations were according to those of Ministry of Social Affairs and Health [25]. Intervention group children are given a 30 to 60 minutes longer appointment with a PHN in child health care clinic at routine yearly control visits at 1, 2, 3, 4 and 5 years of age [Table 1. During these visits counseling on healthy diet and amount of physical exercise/day is given as well as advice about age-appropriate sleep and screen time. These issues are addressed with help of the Finnish Heart Association’s “The Smart Family- exercise and nutrition guidance method” [Additional file 1. This method includes an interview card, a folder with e.g. informative images to be studied together with the family, and a separate information folder for PHNs. With the help of the card the family estimates its own habits regarding lifestyle and it functions as a tool for motivational interview. The folder contains motivational pictures and written information about healthy diet and physical activity. The PHNs in both maternity and child health care were trained in three separate group sessions for the intervention group intensified lifestyle counseling, and thereafter reminded about the intervention protocol at least once yearly by e-mail. The training of PHNs to use The Smart Family- exercise and nutrition guidance method was performed by Finnish Heart Association’s educator in a whole day training session. The control group is getting the usual counseling used in Finnish maternity and child health care centers.

The primary outcomes of the intervention are difference and changes in BMI z-scores among the study group offspring, and the proportion of children being overweight according to the new Finnish cut-off-values for (percentile curve passing through BMI 25 kg/m²) or obese (percentile curve passing through the BMI 30 kg/m²) [26]. PHNs measure children’s weight and length/height at 4 and 6 months of age and thereafter at 1, 2, 3, 4, 5 and 6 years of age.The final primary outcome measure time point will be at six years of age.

The secondary outcomes are duration of breastfeeding, frequency of offspring dietary intake of sugary beverages, pastry, sweets, fruit, berries, vegetables, type butter or margarine used and frequency of eating takeaway food as well as eating pattern are recorded yearly. Daily average screen and sleep time are recorded. Waist circumference (WC) and blood pressure (BP) are measured at 2, 3, 4, 5 and 6 years of age. Metabolic markers (fasting triglycerides, HDL-cholesterol, glucose, insulin and alaninaminotransferase) are measured at 2, 4 and 6 years of age.

Mothers weight gain, BP, sleep duration, mother’s own estimate about weekly physical exercise during pregnancy, results of 2-hour OGTT at 27–28 weeks of pregnancy were recorded in questionnaires filled in partly by the PHN and partly by the mothers once during the first, second and third trimester of pregnancy. The PHN measured and wrote down the physical measures in the questionnaires except for the control group’s measures during pregnancy, which were filled in by the mothers themselves. The mothers transferred this data to study questionnaire from their maternity card, which was filled in by a PHN during pregnancy. The offspring data is recorded in questionnaires, which are filled in at the yearly appointment with the PHN. Long term illnesses affecting growth are recorded. The PHNs measure the length/height, weight, BP and WC of the child and add them to the questionnaire. The children’s weight is measured to the nearest 0.01 kg without clothes until one year of age, and thereafter to the nearest 0.1 kg on a standard electronic scale with light clothing. Children under 2 years are measured in recumbent position and thereafter in standing position to the nearest millimetre with a standard stadiometer. WC is instructed to be measured on the midpoint between the lower costal border and the iliac crest. BP is measured by PHN using an automated BP monitor (Omron M6) under standard conditions with two repeated measurements. The children’s dietary intakes are recorded yearly by questionnaires filled by mother or father of the child, and are measured as average consumption/day or week. The children’s eating patterns are also recorded. The time children spend physically active is measured as parents estimate of time spent outdoors, moderate intensity or structured physical activity time as hours/day or week. Daily average screen time and sleep time are measured as parents’ estimate yearly. Fasting blood samples are collected in the local medical laboratory used by health centre in Vaasa (Vaasa Central Hospital) and analysed using standard automated techniques. Laboratory results are recorded by the researcher directly from the laboratory score sheet. The timing of questionnaires, physical measurements and laboratory tests are listed in Table 2.

Characteristics of the study participants will be described using means and standard deviations or frequencies and proportions. The child’s size during follow-up will be analysed using weight and length/height converted to BMI (weight (kg)/height (m²))-for-age and weight-for-length/height and their SDSs (z-scores) according to the recently updated Finnish growth reference (26). Exact age of the child will be used in all growth analyses. Mixed-effects linear regression models will be used to analyse the association of weight-for-length/height z-score and BMI z-score over time by group (intervention/control). These models allow for a difference between groups at baseline, linear changes of z-score over time and the difference of improvement between groups, which can be viewed as the intervention effect (i.e. interaction term). The goodness-of-fit of the models will be evaluated visually by normal probability and residual plots and also tested by the normality of the residuals (Kolmogorov-Smirnov test). All analyses will be performed using STATA software (version 12.0 for Windows), StataCorp LP, Texas, USA.