1. Introduction
Young children’s food intake, screen time, and physical activity (PA), commonly referred to as energy balance-related behaviors (EBRBs) [
1], are of importance since they can predict the future weight status and health of children [
2,
3,
4]. A socio-economic status (SES) gradient exists already in preschoolers’ EBRBs; those with low SES family backgrounds tend to have less healthy EBRBs such as higher intake of sugary foods or beverages and excessive screen time [
5,
6,
7].
Home and an early childhood education and care center, hereafter preschool, are the settings where three to six-year-olds spend most of their time, and it is therefore important that these environments promote healthy EBRBs including sufficient PA and fruit and vegetable (FV) consumption [
8,
9,
10]. Reviews have concluded that EBRB interventions should be conducted at preschools and homes simultaneously in order to be successful [
11,
12]. Preschool-based family-involving interventions have been reported to be promising [
12,
13,
14,
15], although some studies show no effects on EBRBs [
12,
14,
16]. This has raised discussion on intervention design and implementation in families [
12]. When designing interventions for the general population, they should reach and show higher effects on those needing it most, namely those with low SES backgrounds [
5,
17]. To date, knowledge of the equity effectiveness of EBRB interventions among children is sparse [
18,
19]. Promoting several EBRBs simultaneously is challenging, as the aim can be to both promote healthy behaviors and discourage unhealthy behaviors. Strategies can differ, a review concluding that promoting PA among young children is successful when focusing on the preferred behavior, rather than focusing on decreasing sedentary time such as lying or sitting down [
20].
Strengthening children’s self-regulation (SR) skills in parallel to promoting children’s healthy EBRBs could be an effective strategy in interventions [
21,
22]. Self-regulation is a multidimensional concept, briefly described as the capacity of a goal-directed behavior to regulate actions, emotions, and cognitions [
23]. Cognitive SR skills refer to executive functioning such as self-monitoring to plan and proceed toward long-term goals [
24,
25,
26], whereas emotional SR skills refers to capacities such as being able to recognize one’s own feelings and staying calm in stressful situations [
24,
25]. Associations between children’s SR skills and less favorable EBRBs and weight status have been found [
21,
22,
24,
25]. The Head Start study tested the strategy of strengthening young children’s SR skills alongside promoting their healthy EBRBs [
27]. The intervention included four arms: intervening on EBRBs and SR skills; intervening on EBRBs; intervening on SRs skills; and no intervention. Effects were seen in lower sugar-sweetened beverage consumption in the study arm promoting EBRBs and SR skills compared with the other arms [
27].
The Increased Health and Wellbeing in Preschools (DAGIS) intervention aimed to promote preschoolers’ (aged 3–6 years) healthy EBRBs and SR skills. The assumption was that there would be greater effects on children from families with low parental educational levels (PEL), also assuming a reduction in any health gaps between children with low and high PEL backgrounds [
28]. The intervention development process was guided by the Intervention Mapping (IM) framework [
29] and the process is described elsewhere [
28]. A cross-sectional study served as the needs assessment [
7,
28], and based on these findings, there were three main aims: to reduce children’s screen time; to reduce the consumption of sugary everyday foods and beverages; and to increase vegetable consumption. In these three behaviors, the needs assessment showed less favorable behaviors among children with low PEL background [
28]. To promote alternatives to the reductions, additional aims were to increase fruit and berry consumption and total PA (light, moderate, and vigorous intensity) [
28]. In addition, the intervention aimed to strengthen children’s SR skills. Activities were planned to suit families with low PEL backgrounds.
In Finland, 78–86% of three to six year-olds attend municipality-driven preschools [
30]. Therefore, preschools offer a good setting for interventions. As screen time and sugary food and beverage consumption occurs mostly at home [
31], homes were considered as an equally important intervention setting. The developed program lasted 23 weeks, and was divided into five themes: SR skills; PA; fruit and vegetables; screen time; and sugary foods and beverages. Each theme was in focus for four to five weeks.
In this study, we aimed: (1) to evaluate the effects of a preschool-based family intervention on children’s EBRBs and SR skills, and (2) to evaluate whether effects were stronger among children with low PEL background than among those with high PEL background.
3. Results
The average age of children in the study was 5.24 (±1.06) and 5.14 (±1.04) years for the control and intervention groups, respectively. Even though most characteristics were similar in the groups, a higher percentage of children with high educational level parents were found in the control group (26%) than in the intervention group (18%) (
Table 1).
Table 2 shows the descriptive results for children’s EBRBs and SR skills according to the intervention and control group, at baseline and at follow-up, whereas the corresponding results according to PEL are presented in
Supplementary Table S2. Children had about the same daily screen time in the intervention and control groups at baseline (
Table 2), but low PEL children had higher screen time than the other groups (
Supplementary Table S2). The FV consumption at baseline was higher in the high PEL groups than in the other groups (
Supplementary Table S2).
Table 3 shows the comparison between the intervention and control groups at follow-up adjusted for respective baseline outcome values.
Figure 2 and
Figure 3 present the mean of the main outcomes (descriptive values from
Table 2) at the baseline and follow-up for the intervention and control groups, and for the PEL subgroups of the intervention group.
There were no significant differences detected in follow-up between the intervention and control groups for children’s total screen time, total PA, consumption frequencies of sugary everyday foods and beverages, sugary treats, and FV, and cognitive and emotional SR skills (
Table 3).
The results between the baseline and follow-up within the control and intervention groups differed for some EBRBs and SR skills (
Table 3, see means in
Figure 2). In the intervention group, the change between baseline and follow-up in total screen time was not significant, whereas there was a significant increase, approximately 4.5 min/day, in screen time in the control group (
p = 0.028,
Table 3,
Figure 2A). The control group significantly increased in total PA on average by 24 min/day (
p < 0.001), and the intervention group had a significant increase of 27 min/day (
p < 0.001,
Table 3 and
Figure 2B). There was an increase in sugary treat consumption frequency in both groups (
p < 0.001 in both groups,
Table 3). In the intervention group, there was a trend, albeit not significant (
p = 0.088), where FV consumption frequency increased (
Table 3,
Figure 2E). A positive significant change in points in cognitive SR skills was observed in the intervention group (
p = 0.011,
Table 3,
Figure 2F).
Similar comparisons of children’s EBRBs and SRs skills at follow-up stratified by PEL and the comparison between baseline and follow-up for intervention and control groups stratified by PEL are presented in
Table 4. To illustrate the results within the separate PEL intervention groups, figures are presented with the mean of main outcomes at baseline and follow-up (
Figure 3).
No significant differences were found when examining EBRBs and SR skills stratified by PEL (
Table 4). In follow-up, there was a borderline significant result in cognitive SR skills when comparing low PEL intervention and control groups (
p = 0.051).
Within the groups, the low PEL control group decreased their cognitive SR skills (borderline significance,
p = 0.052). The total PA increased significantly within all intervention and control groups when stratified by PEL (
p < 0.001 for all subgroups,
Table 4,
Figure 3B). The sugary treat consumption frequency increased within low PEL control and intervention groups (
p < 0.001 in both groups), and in the middle PEL control group (
p = 0.027,
Table 4,
Figure 3D). Cognitive SR skills strengthened in the middle PEL intervention group (
p = 0.038,
Table 4,
Figure 3F).
4. Discussion
We detected no differences in EBRBs or SR skills between the intervention and the control group in our preschool-based family-involving RCT. Furthermore, changes in children’s EBRBs according to PEL did not differ between the intervention and control groups at follow-up, although a borderline significant result emerged in low PEL children in the intervention group, improving their cognitive SR skills compared with the corresponding control group (p = 0.051).
A possible reason for not detecting significant intervention effects might be that the goals set were unrealistic (0.74 times/day decrease in sugary foods and beverages), or it would have required a higher number of children. Our study was a complex multicomponent intervention of relatively short duration. Each of the five program themes were focused on for 4–5 weeks, which could have been too short a duration for changes to occur. Therefore, further evaluation of the effects is needed. Furthermore, the analysis did not show stronger intervention effects in low PEL children. Still, cognitive SR skills strengthened in the low PEL intervention group compared with the low PEL control group, and the results bordered on statistical significance. Within the low PEL control group, cognitive SR skills decreased; also here the results did border to reach statistical significance. However, a significant improvement in cognitive SR skills occurred among middle PEL intervention children. Since the above-mentioned increases in cognitive SR points when comparing control and intervention group were small, these results might lack practical implication. The Head Start intervention showed improvements in SR skills and a decrease in sugar-sweetened drink consumption in the group that received the intervention promoting both EBRBs and SR skills, compared with the other three groups [
27]. Although the aims of that study and ours were similar, the results are not totally comparable. The age group in Head Start was slightly older (4–9 years), and SR skills were measured by another instrument. In both studies, activities to strengthen SR skills were mainly conducted in preschools, whereas parents were the main target when promoting healthy EBRBs. It was discussed that parents might not have been sufficiently engaged, which may have led to null results regarding the children’s EBRBs, which may also be the case in the DAGIS.
Within the intervention and control group, several significant changes occurred in the EBRBs. The control group increased their screen time by approximately 4.5 min/day, whereas no changes were detected within the intervention group. For the control group, it had about a 30 min/week higher screen time, which might eventually harm energy balance, weight status, and development of SR skills. The results of the control children followed the trend that screen time increases with age among young children [
40]. The ToyBox study also did not reveal an overall positive effect on screen time [
16], nevertheless when including a process evaluation, a reduction in computer/video games time was shown [
14]. Subgroup analyses in ToyBox showed less TV time during weekends in the intervention girls [
16], and subgroup analyses should also be considered in the DAGIS study.
The total PA increased in the control and intervention group. A recently published European study reported that moderate-to-vigorous PA increased from the age group of 2–3 years to 4–5 years, and further to 6–7 years [
41]. The trend might explain the results in the DAGIS. Moreover, the follow-up occurred in spring, when there are more daylight hours than at the baseline in autumn. Studies have revealed that the higher the temperature and the more daylight present, the higher the level of PA among children [
42,
43]. The municipality, in which all preschools participated, simultaneously runs a training program for all early educators aimed at increasing preschool PA, which has increased all children’s preschool PA independently of intervention status. Previous interventions have reported no effects on children’s PA [
44,
45,
46], and discussion has ensued on whether short durations such as six weeks of promoting PA are sufficient to detect an increase in children’s PA [
16,
47].
The follow-up results for sugary everyday food and beverage consumption outside preschool hours did not differ between the intervention and control groups. The reduction was mainly supposed to happen at home, as these foods are seldom served at Finnish preschools [
31]. The program implementation in families might have been weak, leading to no changes. This needs to be further studied by analyzing the processes in the intervention. We found an increase in sugary treat consumption in both the control and intervention low PEL groups (
Supplementary Table S2), but no changes in the middle or high intervention groups. It seems that as children grow older, the consumption increases, especially in low PEL groups, which might lead to a greater gap between the PEL groups. The change in FV consumption did not differ between the intervention and control groups. However, while the control group had a stable consumption of FV at both time-points, the consumption frequency in the intervention group increased by 1.3 times/week. Similarly, some intervention studies have shown improvements in FV consumption [
48], although a systematic review concluded that multicomponent FV interventions have provided low evidence of increasing FV consumption [
49].
When developing the DAGIS intervention, the focus was set on understanding the low educational level context and how to, by means of a universal intervention, reach those with low PEL backgrounds [
28]. One strategy was to produce easy-to-read materials as the ToyBox intervention study discussed that the lack of significant results for children’s food consumption might have been due to the intervention materials being insufficiently tailored to those with low education levels [
13]. The DAGIS logic model of change included primary outcomes, which were seen as the most important determinants for explaining socio-economic differences in children’s EBRBs. The main primary outcomes (i.e., adults role modeling and changes in the environment in availability and accessibility of, for example, foods and screens), should be examined next. It is more likely to see changes in these due to the relatively short duration of the intervention. Generally, it has been concluded that availability and accessibility (foods, screens) in the home environment would be of great importance for children’s health behaviors in low PEL families [
13].
As this study includes the intention-to-treat effect analysis, it was assumed that all intervention preschools and families conducted the program in the same manner and at the same intensity. Further analysis including fidelity and implementation degree of the program will yield a deeper understanding of the effects. The importance of the implementation degree has been discussed in conjunction with null results in multicomponent interventions [
50].
The DAGIS intervention study had limitations that should be acknowledged. The short intervention time, in all, five months, was a limitation, but the project as a whole needed to be conducted during a preschool year. Previous discussion has questioned whether a short time period is adequate for children to change their EBRBs [
13,
44]. In addition, children’s baseline consumption of FV, mean three times/day outside preschool time, was fairly high, which sets challenges for achieving an increase. Furthermore, reliably measuring food consumption is challenging. However, reproducibility and validity of our parental FFQ have been tested [
36,
38]. Still, the FFQ reflects the foods eaten during the last week outside preschool time and does not allow for analysis of whether food consumption changed at preschool. The 10-item questionnaire assessing two dimensions of children’s SR skills had three answer categories, which might not have been sensitive enough to capture changes. Many instruments are available to assess children’s SR skills, but no consensus exists on their validity in evaluating this multidimensional concept [
51]. Finally, the sample size might not have been sufficiently large to detect significant results. The power calculations were conducted based on means and standard deviations from the DAGIS cross-sectional survey [
7]. Some dissimilarities exist between these two studies such as the number of preschools and municipalities and the proportion of low PEL families participating, which might have led to an underpowered study.
A strength of the study is that the study development was guided by the IM framework [
28], which enabled systematic planning. The logic model of change was formed on the best existing knowledge, and on a comprehensive evaluation of the Finnish preschool-family context [
10,
28]. This enables further systematic evaluations of the processes. The fairly high response rate of families, 47%, and having all preschools from one municipality participating including diverse preschools as well as diverse families can be seen as a strength. The high response rate indicates a lower selection bias among the participants. In addition, slightly more than 30% of the participating families had low education levels. It is often seen as a challenge that the less educated tend not to participate in intervention studies [
52]. The study also included a combination of instruments such as the accelerometer for assessing PA, a validated screen time diary, and a validated FFQ for robust assessment [
35,
38].
The fairly new approach of simultaneously strengthening children’s SR skills and promoting their EBRBs can be seen as a strength and also as a risk. To the best of our knowledge, this approach has been evaluated in one other study [
27], where it was discussed that the next step should be integrating SR skill promotion into the EBRB context. In the DAGIS study, this can be seen as a strength as the program enhanced SR skills, while simultaneously promoting EBRBs by adding more materials to the existing program. The materials and methods for the program also underwent pretesting [
28].