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A Pilot Study: Does Obesity Begin in the First Year of Life?

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A Pilot Study: Does Obesity Begin in the First Year of Life?
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    http://cpj.sagepub.com/  Clinical Pediatrics  http://cpj.sagepub.com/content/early/2013/03/27/0009922813482750The online version of this article can be found at: DOI: 10.1177/0009922813482750 published online 28 March 2013 CLIN PEDIATR  Susan M. Ludington-Hoe, Lisaann S. Gittner and Harold S. Haller A Pilot Study : Does Obesity Begin in the First Year of Life?  Published by:  http://www.sagepublications.com  can be found at: Clinical Pediatrics  Additional services and information for http://cpj.sagepub.com/cgi/alerts Email Alerts: http://cpj.sagepub.com/subscriptions Subscriptions:  http://www.sagepub.com/journalsReprints.nav Reprints:  http://www.sagepub.com/journalsPermissions.nav Permissions: What is This? - Mar 28, 2013OnlineFirst Version of Record >> at TENNESSEE STATE UNIV on April 4, 2013cpj.sagepub.comDownloaded from   Clinical PediatricsXX(X) 1  –6©   The   Author(s) 2013Reprints and permission: sagepub.com/journalsPermissions.navDOI: 10.1177/0009922813482750cpj.sagepub.com Original Article Introduction Recent research shows that obesity might begin much earlier in life than previously believed, 1-4  creating a lifelong weight struggle and numerous comorbidities 5  that reduce life span. Once it appears, obesity tends to remain throughout a life course 6  and systematic reviews reveal that rapid growth in infancy can be associated with a greater risk of later-life obesity. 7,8  Overweight school-age children frequently become overweight ado-lescents and, in turn, overweight adults. 7,8  Similarly, children who are normal weight at 2 years are less likely to become overweight adults. 9  A few studies have evaluated weight gain during infancy because of the associations between early weight and later obesity 10,11 ; upwardly crossing more than 2 or more weight-for-length percentiles in the first 6 months postbirth, but not in later life, was associated with obesity 5 and 10 years later. 11  Additionally, at any time in the first 2 years post- birth, being overweight was a strong predictor of obe-sity at 5 years of age. 12  One study showed that tracking  body mass index (BMI) during well-child visits pro-vided a practical prediction of children’s growth pat-terns. 13  However, current studies of weight-for-length or BMI trajectories have had limited data points (ie, 2 11 , 3 13 , 4 11 , or 6 12  in the first 5 years and 8 over the first 14 years of life 14 ). Discrimination of differences within the first year of life of children who will or will not become overweight or obese has been difficult.Previous studies of large databases have included children who could have been ill or injured, both of which could change eating patterns or growth, 15,16  thus this study is different because only healthy children with no injuries were included. We conducted a retrospective chart review to calculate BMI from routinely measured weight and length data from 7 well-child visits during the first year of life for infants who remained healthy and uninjured from birth to 5 years age. Study aims were to ( a ) describe growth patterns in the first year of life in cohorts established by their 5-year World Health Organization (WHO) obesity classifications for BMI 1 Case Western Reserve University, Cleveland, OH, USA 2 Texas Tech University, Lubbock, TX, USA Corresponding Author: Lisaann S. Gittner, Department of Political Science, Public Administration Program, Texas Tech University, Holden Hall, Lubbock, TX 79409, USA.Email: lsg1@zips.uakron.edu A Pilot Study: Does Obesity Begin in the First Year of Life? Susan M. Ludington-Hoe, PhD, CNM, FAAN 1 , Lisaann S. Gittner, PhD 2 , and Harold S. Haller, PhD 1 Abstract  Aim . To determine if growth patterns in healthy infants can identify associations with obesity at age 5 years.  Method  . Body mass index growth patterns from birth to 1 year were described for cohorts of children who were classified at 5 years as normal weight (n =  61), overweight (n =  47), obese (n =  41), and morbidly obese (n =  72). A longitudinal analysis of body mass index means based on the age postbirth was conducted and graphed. Results . Distinctions in growth patterns were evident before 1 year postbirth. Children who were normal weight at 5 years demonstrated a growth pattern in the first year that differed from children who were overweight, obese, or morbidly obese at 5 years. Conclusions . Obesity growth patterns were seen in infancy and are clinically important because identification of infants who do not fit a normal weight pattern can occur and thus guide individualized interventions in the first year postbirth while precursors of later health are still forming. Keywords pediatric obesity, body mass index, infant growth  at TENNESSEE STATE UNIV on April 4, 2013cpj.sagepub.comDownloaded from   2 Clinical Pediatrics    XX(X)  percentiles and ( b ) determine if the first-year BMI val-ues were associated with 5-year BMI values. Methods Only healthy infants were studied. Data were obtained from a health maintenance organization in the Midwestern United States. After institutional review  board approval, a longitudinal study using retrospective chart review was conducted. All records of mothers and children born between 1997 and 2001 (to capture this  period of increasing childhood obesity) and birth and well-child visit records at 1 week; 2, 4, 6, 9, and 12-months; and 5 years were reviewed. Three data col-lection teams were trained to ≥ .8 reliability by percent-age agreement on sample criteria and data extraction  procedures. Because of the retrospective nature of the study, height and weight measurements were assumed to be accurate and reliable to within 1% to 2% as has  been found in clinical practice. 17  The actual age in days of the infant on the date of the well-child visit was used in the development of the growth pattern graphs for each individual using a longitudinal model that was  parameterized in the same way as the models used to generate WHO standard growth curves. 18 Inclusion criteria were as follows: complete medical records for at least 8 of 12 well-child visits from birth to 5 years, singleton birth born at term after an uncompli-cated gestation, appropriate weight-for-gestational age at birth, no medical complications or congenital abnor-malities other than nonfood allergies, no hospitaliza-tions, no injuries requiring medical intervention, not classified as underweight ( < 25 percentile as defined by WHO BMI criteria 18 ) at age 5 years, and the mother did not have prepregnancy or gestational diabetes. Excluded infants had similar demographic characteristics as those included.Eight hundred charts were randomly selected with half below and half above the 95th BMI percentile for children at 5 years. Charts were manually reviewed for inclusion criteria, yielding 221 valid maternal–child charts. BMI was calculated for each individual at each time point from the recorded height and weight using the formula: BMI =  [weight (pounds) ×  703]/[height (inches)] 2  which are calculated in children the same way as BMI for adults. However, the limits for classification of overweight and obesity varies for all ages from 1 to 18 years in children. The children’s charts were then grouped into cohorts by obesity status at 5 years (ie, nor-mal weight (n =  61) BMI ≥  25th to < 85th percentile, overweight (n =  47) BMI ≥  85th to < 95th percentile, obese (n =  41) BMI ≥ 95th to < 99th percentile, or mor- bidly obese (n =  72) BMI ≥ 99th percentile) categorized  by WHO BMI criteria. 18  There were 110 males and 111 females.Sample size using Cohen’s statistical power analy-sis, 19  with power =  .80; effect size =  .50 (equivalent to 0.5 BMI) and α =  .05 yielded 51 subjects for each cohort. Thus, required sample size was 51 for each cohort (nor-mal weight n =  61, overweight n =  47, obese n =  41, and morbidly obese n =  72).Graphs of the longitudinal analysis of means were developed to present the earliest divergence of each cohort’s average BMI pattern from the other cohorts’ average patterns. 20  The  x -axis (age) was derived by lon-gitudinal analysis based on the average number of days since birth at each visit. The  y -axis (BMI) was derived from the arithmetic average of the average BMI for the cohorts rather than the weighted average because the cohorts were not equal. Correlations between BMI  prior to 1 year and BMI at 5 years of age were con-ducted using the Pearson product moment correlational analysis. Results Body Mass Index Values The normal weight cohort had the highest birth BMI (14.1 ±  1.7) compared with the overweight (13.6 ±  2.0), obese (13.5 ±  1.3), and morbidly obese (13.8 ±  1.6) cohorts. By 1 week postbirth, the normal weight cohort’s BMI dropped to the lowest BMI (13.3 ±  1.2) compared with the other cohorts (overweight =  13.6 ±  1.7, obese =  13.9 ±  1.0, morbidly obese =  13.7 ±  1.3). From 1 week onward, the normal weight cohort’s BMIs for all time points was the lowest of all cohorts (Table 1).Correlations between first year of life BMIs and BMI at 5 years were seen; significant positive correlations in BMIs existed in the entire data set (  p   ≤  .01-.05), repre-senting autoregression between one BMI and the next. The earliest significant correlation with 5-year BMI was at 2 months ( r    =  .181,  p   =  .000) and every BMI after 2 months also correlated with BMI at 5 years (Table 2). Body Mass Index Patterns The average BMI for each cohort at the mean age for each visit are graphically displayed in Figure 1. The normal weight cohort’s BMI decreased from birth to 1 week; it was the only cohort to have a decrease in BMI (birth weight loss). Between 1 week and 2 months, all cohorts had an increase in BMI; the obese and mor- bidly obese cohorts had a sharp rise in BMI compared with a much smaller BMI rise in the normal weight at TENNESSEE STATE UNIV on April 4, 2013cpj.sagepub.comDownloaded from   Ludington-Hoe et al 3 cohort. Another noteworthy graphic difference between cohorts’ BMIs emerged by 2 to 4 months: the normal weight cohort’s BMI was distinctly lower than and diverging from the patterns of the other cohorts. Between 4 and 6 months, the overweight, obese, and morbidly obese cohorts had much higher BMIs than the normal weight cohort. At 6, 9, and 12 months, the nor-mal weight cohort’s BMIs stabilized around 16.5 (16.4 ±  1.3, 16.5 ±  1.3, 16.3 ±  1.5, respectively) whereas the other cohorts stabilized at higher BMIs, around 17, after gaining 3 to 4 values (overweight =  17.4 ±  1.8 [6 months], 17.0 ±  1.6 [9 months], 16.8 ±  1.5 [12 months]; obese =  17.8 ±  1.5 [6 months], 17.5 ±  1.5 [9 months], 17.7 ±  1.6 [12 months]; and morbidly obese =  17.9 ±  1.9 [6 months], 18.2 ±  1.9 [9 months], 17.9 ±  2.1 [12 months]). Within the first year postbirth, the obese and morbidly obese cohorts’ BMI pattern differed from the normal weight cohort’s by being chronically high and continuously increasing (Figure 1). Discussion Body Mass Index Values Our findings suggest that BMI gains of 3 to 4 values in the first year may be an early warning sign of later obe-sity, supporting one study in which children statistically significantly above the height-weight 50th percentile in the first year postbirth became obese adults 10  and stud-ies by Yucel et al 21  and Eriksson et al 10  in which BMIs chronically above the 50th height-weight percentile at all ages up to 12 years predicted adult obesity. Table 1.  Body Mass Index (BMI) Descriptive Statistics for Normal Weight, Overweight, Obese and Morbidly Obese Cohorts.Normal WeightOverweightObeseMorbidly ObeseBMI AgenMeanSDnMeanSDnMeanSDnMeanSDBirth6014.11. 74913.62.04113.51.37213.81.61 wk5913.31.24813.61.74013.91.07013.71.32 mo5815.51.54615.91.73616.31.56616.72.04 mo5216.11.24116.81.93517.51.75517.71.86 mo5516.41.34217.41.83317.81.55217.91.99 mo4516.51.33517.01.63017.51.54718.21.91 y5316.31.53616.81.53717. 71.65917.92.15 y6015.50.94917.40.34118.50.57222.23.1 Table 2.  Correlation of Body Mass Index (BMI) From Birth to 1 Year of Age With 5-Year BMI for All Cohorts Combined. Correlation (n)Birth1 wk2 mo4 mo6 mo9 mo1 y5 yBirth— 1 wk.465**— (217) 2 mo.285**.427**— (206)(202c) 4 mo.166*.281**.614**— (183)(180)(175) 6 mo.151*.313**.585**.806**— (182)(179)(172)(153) 9 mo.064.197*.493**.720**.795**— (157)(155)(152)(138)(134) 1 y.043.175*.373**.629**.656**.712**— (185)(182)(174)(158)(158)(141) 5 y−.0460.125.181**.269**.237**.362**.307**—  (222)(217)(206)(183)(182)(157)(185) * p   <  .05. ** p   <  .01.  at TENNESSEE STATE UNIV on April 4, 2013cpj.sagepub.comDownloaded from   4 Clinical Pediatrics    XX(X) The significant sequential correlations reported here are consistent with the findings of Huus et al 22  that showed BMI >95th percentile at 1 year was significantly correlated with increased risk of obesity at 5 years. The correlations support the differences in BMI patterns and values reported here, even though the correlation matrix did not take into account the conditional effect of BMIs which are consecutive in time. The fact that each BMI from 2 months onward was significantly and positively correlated with the next and to 5-year BMI supports pre-vious reports of “once obesity occurs, it remains.” 7,8  Two months postbirth may be the time to begin counsel-ing and or/interventions to minimize future risk of or continuing obesity. Body Mass Index Patterns An obesity growth pattern was detected by 4 months of age in the obese and morbidly obese cohorts, con-firming previous reports that rapid and consistent sequential increases in weight, height, and BMI pat-terns from 6 months to 1 year suggest development of later life obesity. 1,21,23,24  Our BMI patterns of healthy full-term infants are similar to the findings of Casey et al 23  that first-year weight gain in low birth weight infants predicted the development of obesity by 8 years of age. Other studies show that the earlier BMI increases by 3 or more BMI values from birth BMI, the more likely the child will be overweight later in life, 21  the same as was found in our data. Our findings also concur with those of Taveras et al 11  in which chil-dren who gained excessive weight in the first 6 months  postbirth, as measured by crossing more than 2 weight-for-length percentile lines on the Centers for Disease Control and Prevention growth charts, had the highest risk of being obese at 5 years. The consistent BMI increases in the obese and morbidly obese cohorts may be due to their weight increasing more than their height, which is common if infants experi-enced early cereal feedings. 24  Stunkard et al 25  found that 3-, 6-, and 9-month caloric consumption predicted  body size, growth pattern, and metabolic rate at 2 years. Thus, nutrition cannot be discounted when explaining early life obesity.Also, predisposing genetic influences can lead to early fat deposition and weight gain. 26,27  Brown adipose tissue in the newborn does not disappear, 28  remaining instead as an active source of adipogenesis from infancy into adulthood. 29  Brown adipose tissue may explain how increasing weight gain during the first year is Figure 1.  Growth patterns over the first year for normal weight, overweight, obese, and morbidly obese cohorts (BMI =  body mass index).  at TENNESSEE STATE UNIV on April 4, 2013cpj.sagepub.comDownloaded from 
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