Environmental characteristics of early childhood education and care, daily movement behaviours and adiposity in toddlers: A multilevel mediation analysis from the GET UP! Study

Highlights

• No indirect effect of environment on adiposity was through movement behaviours.

• There was no direct effect of the environmental characteristics on adiposity.

• Two environmental characteristics was positively associated with MVPA.

• “Listening and talking” was positively associated with nap(s) duration.

Abstract

Study objective

This study aimed to examine the direct effects of environmental characteristics of early childhood education and care (ECEC) centres on adiposity, and the indirect effects through daily movement behaviours (physical activity, sedentary time and naps).

Methods

274 children (average age 19.73 ± 4.15 months) from 27 ECEC centres participated in this study. Environmental characteristics of ECEC centres were rated using the Infant/Toddler Environment Rating Scale-revised edition (ITERS-R). Daily movement behaviours were assessed using 24-h accelerometry. Body mass index z-scores were used to indicate adiposity.

Results

There were no significant direct effects or indirect effects of environmental characteristics on toddlers’ adiposity through daily movement behaviours. However, the environmental characteristics of “personal care routine” (B=0.72, p = 0.041) and “activity” (B = 0.87, p < 0.050) were positively associated with the percentage of time these toddlers spent in moderate-to-vigorous physical activity (MVPA). “Listening and talking” was also positively associated withnap(s) durations (B = 4.08 p = 0.001).

Conclusion

The relationships between environmental characteristics of ECEC centres and adiposity in toddlers, as well as, the mediating roles of daily movement behaviours still need confirmation by future longitudinal and experimental studies with long follow-up periods. At the same time, a broader spectrum of environmental characteristics of these settings needs to be examined with toddlers’ adiposity in future studies; other potential mediators may also need to be taken into considerations.

Introduction

The global prevalence of overweight and obesity, in children under the age of five, increased from 4.2% to 6.1% between 1990 and 2010, and is expected to reach 9.1% by 2020 (De Onis et al., 2010). This is of concern as overweight and obesity at these ages may have detrimental health effects throughout life, as it is known that higher levels of adiposity in the early years track into later childhood (Penny et al., 2016) and adolescence (Cunningham et al., 2014). Moreover, rapid weight gain in the first two years of life has been associated with an increased risk of adult overweight (Adair et al., 2013). Therefore, there is a need to prevent and to address overweight and obesity in young children. To do this, a better understanding of the factors that associated with early childhood adiposity is needed.

The environment plays an important role in the development of childhood overweight and obesity (Baidal et al., 2016, Casey et al., 2014, Nishtar et al., 2016). Young children are especially susceptible to environmental cues that promote obesity-related behaviours, because they may not be well prepared to make informed decisions to maintain a healthy weight status (Hill et al., 2003, Nutbeam et al., 1989, Patrick and Nicklas, 2005). Given the high attendance rate of young children in formal early childhood education and care (ECEC) centres in several countries (Laughlin, 2013, Statitics ABo, 2015, OECD, 2016), many young children are exposed to these environments for most the day, which may have substantial influence on their weight status (Chambers, 2017). Indeed, a recent systematic review identified 22 environmental characteristics of ECECs that have previously been examined in associations with young children's weight status (Zhang et al., 2017), and concluded that those relationships were likely to be mediated by energy balance-related behaviours, such as physical activity and dietary intake (Zhang et al., 2017, Gubbels et al., 2014). For example, “active time in ECEC centres”, one of the environmental correlates identified in that review, is likely to influence children's weight status through an indirect effect on children's active levels, while “high sugar and high fat served in ECEC centres” may be associated with children's food choice and energy intake, which, in turn, could affect their adiposity (Zhang et al., 2017). However, the indirect effects of the ECEC environmental characteristics on young children's weight status through these behaviours has not yet been examined (Zhang et al., 2017). An understanding of their mediating roles could help improve efficiency and effectiveness of environmental interventions in ECEC centres, as most of the interventions published so far were designed to prevent and to address early childhood overweight and obesity through changing intermediate behaviours (Zhou et al., 2014).

From a movement perspective, physical activity, sedentary time and sleep can be considered a continuum ranging from high to low/now movement, with the daily time allocation of these behaviours constituting a 24-h period (Chastin et al., 2015, Pedišić, 2014). Since each of these movement behaviours as well as their combination have been associated with several health and developmental outcomes, including adiposity (Chen et al., 2008, Chaput et al., 2017, Carson et al., 2017, Poitras et al., 2017), Australia and Canada have recently published 24-h movement guidelines for the early years, to promote optimal health and development for young children (Okely et al., 2017, Tremblay et al., 2017). As attending ECEC programs usually contributed to a large proportion of daily time for toddlers (up to 11 h), the environments in these settings are likely to influence young children's daily movement behaviours. For example, evidence suggests that ECEC environment may explain up to 50% of the children's daily variations in physical activity (Pate et al., 2004, Pate et al., 2008, Finn et al., 2002, Boldemann et al., 2006), and that several environmental characteristics of these settings (e.g. provision of active opportunities and the presence of outdoor environments) seems to be associated with children's physical activity and sedentary time (Tonge et al., 2016). However, although these two movement behaviours were common intermediate behaviours in most obesity prevention environmental interventions in ECEC centres (Zhou et al., 2014), the indirect effects of the environment characteristics on adiposity through physical activity and sedentary time are not fully understood yet.

On the other hand, daytime napping is an essential part of total sleep in early childhood, particularly during the first 3 years of life (Touchette et al., 2013); and, nap time is part of the daily routine in most ECEC centres (Ward et al., 2007). Indeed, napping duration is more likely to be influenced by environmental settings, rather than by genetic predisposition (Touchette et al., 2013, Brescianini et al., 2011, Fisher et al., 2012). For example, in a Canadian birth cohort study with 995 twins, environmental influences explained a large proportion of variance in the participants’ napping duration once they became toddlers - 33%, 48% and 79% for 18, 30 and 48 months olds, respectively (Touchette et al., 2013). Nonetheless, young children's nap(s) pattern, duration and quality, as well as environmental influences of ECEC centres on nap(s) remain unclear (Benjamin et al., 2009, Thorpe et al., 2015, Staton et al., 2015). Since napping may also play a mediating role in the relationships between environmental characteristics of ECEC centres and adiposity in young children (Zhang et al., 2017), it is important to examine the indirect effect of the environmental characteristics on adiposity through this daily movement behaviour.

Previous studies examining ECEC centre's environments and nap(s) duration in young children have used subjective measures (e.g. proxy-report) (Zhang et al., 2017, Thorpe et al., 2015), to assess napping, which are less accurate than objective measures and may affect the strength of the evidence (Ma and Dill, 2015). Also, there is limited research in this area focus on children under the age of three (Zhang et al., 2017, Kuzik and Carson, 2016).

The aim of the present study was to examine the indirect effects of environmental characteristics on toddlers’ adiposity through physical activity, sedentary time and nap in a sample of Australian toddlers, using objective measures of ECEC centres’ environments and daily movement behaviours. We hypothesized that there are indirect effects of environmental characteristics on toddlers’ adiposity through physical activity, sedentary time and nap.