Childhood obesity

Childhood obesity

Childhood obesity is a global problem. The World Health Organization (WHO) estimates that over 40 million children under 5 years of age are overweight or obese. While once considered a public health issue primarily for high-income countries, childhood obesity rates are rising quickly in middle- and low-income countries, particularly in urban areas (World Health Organization, 2012). The significance of this change in child health status throughout the world is the long term health consequences of obesity, including cardiovascular morbidities and early development of type 2 diabetes. Childhood obesity

International studies provide evidence that excess weight gain during infancy is a significant risk factor for later obesity. A population-based study of infants from the United States (US) found a positive association between rapid weight gain in the first 4 months of life and overweight status at 7 years of age (Stettler, Zemel, Kumanyika, & Stallings, 2002). For American children from low-income minority

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109Prevention of Childhood Obesity: IOM Guidelines for Pediatric Practice

families, excessive weight gain in the first year of life has been associated with a nine-fold increased risk for obesity at age 3 years (Goodell, Wakefield, & Ferris, 2009). Similarly, higher weight-for-length z-scores at 6 months of age have been associated with the increased odds of obesity at 3 years of age (Taveras et al., 2009). These findings are consistent with those of the Avon Longitudinal Study of Parents and Children in England that found rapid weight gain in the first year to be a risk factor for obesity at age 7 years (Reilly et al., 2005). The accumulating research evidence from these studies points to the need for obesity prevention practice guidelines that begin early in life. Childhood obesity

In response to the childhood obesity epidemic, the Institute of Medicine (Institute of Medicine (IOM), 2011) has developed practice guidelines for preventing childhood obesity. Unlike previous public health initiatives that have focused primarily on school age children, the IOM’s Early Childhood Obesity Prevention Policies targets factors related to overweight and obesity from birth to 5 years of age. The IOM infancy-related guidelines are focused on growth monitoring, healthy feeding, sleep, and physical activity. The purpose of this paper is to present an overview of the IOM infancy-related guidelines and highlight research studies that support their implementation in clinical practice. Childhood obesity

Infant Growth Monitoring

The IOM guideline for measuring infant growth is to plot height and weight on WHO growth charts. The rationale supporting use of WHO charts is that the data used to generate these growth curves were collected from a large cohort of children from varying cultures and countries, including Brazil, Ghana, India, Norway, Oman and the US. Additionally, the WHO charts were generated using sample inclusion criteria that specified breastfeeding up to age 12 months, introduction of solid foods at approximately age 6 months, absence of maternal smoking, and living in a household with adequate income (de Onis et al., 2004). This approach to sampling was designed to generate benchmark curves that reflect an ideal growth trajectory for comparison to individual patterns (Garza & de Onis, 2004). Further, the IOM (2011) guideline for growth monitoring in infancy calls for tracking weight-for-length changes throughout the first year and identifying babies at risk for overweight (84.1st–97.7th percentile) and over- weight (N97.7th percentile). Childhood obesity

With respect to growth monitoring, the WHO growth charts also provide useful application for clinical practice. For parents like Benjamin’s who are from countries where food scarcity is prevalent, the overweight status of their infant as seen on the growth chart may be viewed with pride and considered to be a marker for good health and successful parenting. Misconceptions about healthy weight gain, Childhood obesity

however, are not limited to parents from low income countries. Researchers in the Netherlands found that a substantial proportion of parents, regardless of educational attainment and socio-demographic background, did not recognize overweight status in their own children (Jansen & Brug, 2006). Similarly, a recent study in the US found that over 80% of mothers of overweight toddlers were satisfied with their child’s body size and inaccurately assessed their weight as being within a normal range for age (Hager et al., 2012). Another study used a simple assessment measure that can be easily incorporated into a regularly scheduled well child visit (Chaparro, Langellier, Kim, & Waley, 2011). The researchers asked the question “Do you consider your child be overweight, underweight, or about right weight for (his)(her) height?” Almost all mothers classified their overweight or obese child as being about the right weight (93.6% and 77.5%, respectively). While this study focused on preschoolers, using a comparable question for parents of infants may open the door for anticipatory guidance to prevent the rapid or excess infant weight gain that leads to later obesity.

Infant Feeding

The IOM’s (2011) infancy-related guidelines for the prevention of childhood obesity call for health care providers to encourage exclusive breastfeeding in the first 6 months and continuation of breastfeeding with the introduction of solid foods during the second half of infancy. Further, the report underscores the importance of helping parents recognize and respond to infant hunger and fullness cues. Examples of hunger cues in early infancy include sucking on fist, waking and tossing, and opening mouth while feeding to indicate wanting more. Conversely, infant cues to satiety or fullness include behaviors such as turning head away, sealing lips, and decreasing or stopping sucking (USDA, 2013). Childhood obesity

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To date, the findings from health care research related to the healthy infant feeding component of the IOM guidelines are inconsistent. One systematic review of eight interna- tional studies of breastfeeding duration and risk for overweight or obesity in later childhood found that only half of the studies reported a dose response of breastfeeding after adjusting for other known risk factors for obesity (Arenz, Rükerl, Koletzko, & von Kries, 2004). A meta- analysis of the same relationship was conducted using 17 studies from seven countries in Europe and North America (Harder, Bergmann, Kallischnigg, & Plagemann, 2005). The findings strongly supported a dose-dependent associ- ation between longer breastfeeding duration and reduced risk for later obesity. However, due to methodological differences across studies, adjustment for potential con- founders could not be calculated. A later study found a relationship between breastfeeding duration and over- weight at age 4 years, but when the researchers controlled Childhood obesity

110 K.F. Gaffney et al.

for other social and environmental risk factors, the association diminished and was no longer statistically significant (Procter & Holcomb, 2008).

To further examine whether breastfeeding offers a protective factor against later obesity, a study based on the Copenhagen Perinatal Cohort compared the effects of breastfeeding duration and age of introduction to solid foods on body mass index through childhood and adulthood. The researchers found that later introduction of solids (approxi- mately 6 months of age) was protective against later overweight, but did not find a protective effect for longer breastfeeding duration (Schack-Nielsen, Sǿrensen, Morten- sen, & Michaelsen, 2010). Researchers in Northern Ireland found that infants who were introduced to solids prior to 4 months of age were heavier at 7 and 14 months than those in a comparison group who started solids later. Group differences remained significant after controlling for breast- feeding duration (Sloan, Gildea, Stewart, Sneddon, & Iwaniec, 2007). Further, a study using a nationally representative data set in the US that examined the relationship between weight at 12 months of age and adherence to clinical practice guidelines for feeding behaviors found significant associations with breastfeeding intensity during the second half of infancy and age of introduction to solid foods (Gaffney, Kitsantas, & Cheema, 2012). Childhood obesity

In addition to monitoring the source of infant caloric consumption from breastfeeding, formula feeding and solid food, the IOM guidelines recommend that health care providers encourage infant feeding behavior that is respon- sive to hunger and satiety cues. A recent longitudinal study of infants offers potential insight into the role of sensitivity to infant feeding cues in preventing obesity. In a comparison of babies who were fed at breast with those bottle fed (either human or nonhuman milk), those who were exclusively bottle fed gained significantly more weight per month throughout infancy (Li, Fein, & Grummer-Strawn, 2010; Li, Magada, Fein, & Grummer-Strawn, 2012). This finding led researchers to conclude that infant weight gain may not only be associated with type of milk consumed but also the type of milk delivery. They proposed that the underlying processes may be that infants fed at breast develop better self- regulation of intake than bottle fed infants and that mothers who have breastfed their infants may develop improved sensitivity and responsiveness to infant cues of hunger and satiety. Support for this explanation comes from studies of maternal sensitivity that have found lower levels of responsiveness to satiety cues to be inversely associated with infant weight gain (Thompson et al., 2009; Worobey, Lopez, & Hoffman, 2009). However, a limitation of the study was the underrepresentation of Hispanic mother– infant pairs in the sample. This is particularly important in light of a recent US population-based study that found Hispanic children under 2 years of age have a greater prevalence of high weight-for-length than non-Hispanic White, or non-Hispanic Black children (14.8%, 8.4%, 8.7%, respectively; Ogden, Carroll, Kit, & Flegal, 2012). Childhood obesity

Clinical application of the IOM recommendation for responsive infant feeding styles may be the adoption of assessment strategies used in research. For instance, a pilot study by the Project Viva clinical research team derived a “responsiveness to infant satiety” score based on the following items from the infant feeding questionnaire (Taveras et al., 2011):

1. If I did not guide or regulate my baby’s eating, he/she would eat much less than he/she should.

2. If I did not guide or regulate my baby’s eating, he/she would eat much more than he/she should.

3. My baby is never full enough. 4. My baby never seems very hungry.

Mothers were asked to respond with options ranging from strongly agree (1) to strongly disagree (4) with higher scores indicative of more responsive feeding styles. The composite scale was found to have acceptable internal reliability (Cronbach alpha = 0.70) when used with mothers of 6 month old infants. Use of this measurement tool in clinical assessments may be useful in identifying parents and caregivers, like those in our case story of Benjamin, who practice non-responsive infant feeding styles in the belief that they are doing what is best for their babies. Interventions that help them identify and respond positively to infant hunger and satiety cues may reduce the risk of excessive weight gain. Childhood obesity

Infant Sleep

The IOM infancy-related guidelines for obesity preven- tion call on health care providers to help families achieve age-appropriate sleep duration for their babies. While most research about the link between sleep and childhood obesity has been conducted with older children, two studies have examined the relationship between sleep duration in infancy and weight gain. One study of 6 month old infants found that shorter nighttime sleep duration, as measured by both actigraph sleep percentages and parental surveys, was correlated with higher infant weight-for-length ratios. The significance of this relationship persisted after adjusting for potential confounders, such as infant gender, birth weight, and gestational age (Tikotzky et al., 2010). Another study used multivariate regression analyses to predict the effects of infant sleep duration (b12 h/d vs.≥12 h/d) on weight status among preschoolers. The researchers found that infant sleep less than 12 h/d was associated with higher BMI and increased odds of overweight at 3 years of age (Taveras, Rifas-Shiman, Oken, Gunderson, & Gillman, 2008). Repli- cation and extension of these studies with larger and more diverse samples will add the body of evidence that informs practice in this area Childhood obesity

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