Evidence Based Answers CLINICAL INQUIRIES from the Family Physicians Inquiries Network

Robert K Persons, DO, and Does birth weight predict Tristan L. Sevdy, MD, FAAFP Eglin Family Medicine Residency, childhood ? Eglin Air Force Base, Fla William Nichols, MLS Eglin Air Force Base, Fla

Evidence-based answer CopyYes. A for birth evidence-based weight greater answer than 4,000 g (strength of recommendation [SOR]: B, is associated with an increased risk of systematic review and multiple cohort obesity in both childhood and adolescence studies).

Clinical commentary Lifestyle matters, too 4 kg is at increased risk of childhood Few people have more questions than ® Dowdenobesity. However, Health all parents shouldMedia be brand-new parents. Physicians often counseled that the lifestyle choices they answer these inquiries from their pool of make for their child are far more likely than clinical experience or pearlsCopyright handed downFor personalbirth weight to influse uence only future obesity. byClinical mentors. commentary It’s refreshing to be able to Education about appropriate diet and address a parental query on the basis of physical activity is the bedrock from which good evidence rather than empiricism. to attack the childhood obesity epidemic. The data compel us to inform parents FAST TRACK David Krulak, MD, MPH that a new baby who weighs more than Camp Lejeune, NC A birth weight >4,000 g ❚ Evidence summary steatohepatitis, genu varum, and slipped heightens the risk The number of children 2 years and older capital femoral epiphysis.2 The many vari- of obesity who are has tripled in the past ables that have been suggested to infl uence in childhood and 2 decades; the current prevalence of over- childhood obesity include birth weight, weight children and adolescents in the gestational age, parental obesity, socioeco- adolescence US is 15%.1 By contrast with adults—in nomic status, single parent household, and whom overweight and obesity are defi ned birth order.3-5 separately as a body mass index (BMI) above 25 kg/m2 and 30 kg/m2, respec- Birth weight and later BMI: tively—overweight and obesity are syn- Consistently linked onymous in children and are defi ned as a A systematic review of 19 longitudinal, ob- BMI above the 95th percentile for age and servational studies comparing birth weight sex.2 Children and adolescents with a BMI with later BMI indicates that the associa- between the 85th and 95th percentiles are tion between the 2 is positive and consis- considered at risk for overweight.2 tent in multiple cohorts.3 Eleven studies fo- Overweight children are vulnerable cused on outcomes in childhood; another to adverse health outcomes, including 8 measured outcomes into adulthood. , , hyper- Fifteen of the 19 studies (79%), rang- tension, depression, sleep apnea, asthma, ing in size from 1028 to 92,940 subjects,

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409_JFP0608 409 5/20/08 1:05:03 PM INQUIRIES found a positive association between The absolute rate of overweight increased birth weight and later BMI. However, from 8% to 26% among LGA infants. the data were too heterogeneous to com- bine into a single summary measure. One In adolescence, parental weight representative study quantifi ed the rela- may be a factor CLINICAL tive risk (RR) for severe obesity (>95th A prospective cohort study of 1993 white percentile BMI) at 5 years of age as 1.7 LGA infants found a greater propensity to (95% confi dence interval [CI], 1.2-2.9) become obese in adolescence, but only if for birth weights between the 85th and their mothers or fathers were also obese 94th percentiles and 1.8 (95% CI, 1.1- (RR=5.7).7 Children with lean parents did 2.9) for birth weights greater than the not have an increased risk of being over- 95th percentile.3 Studies that didn’t fi nd weight in adolescence. such an association had smaller sample sizes (137 to 432 subjects) and, therefore, Recommendations may have lacked the power to detect an Although major organizations don’t fo- association. cus on infant birth weight as a predictor Gestational . A subsequent of overweight, they do address childhood retrospective cohort survey of 14,881 obesity. The American Academy of Pedi- children born to mothers with gestational atrics states that genetic, environmental, diabetes—and controlled for age, sex, and or combinations of risk factors predispos- Tanner stage—found that the odds ratio ing children to obesity can and should be (OR) for adolescent overweight was 1.4 identifi ed.2 The US Preventive Services (95% CI, 1.2-1.6) for each 1-kg increment Task Force concludes that the evidence is in birth weight.4 The correlation persisted insuffi cient to recommend for or against (OR=1.3; 95% CI, 1.1-1.5) when other routine screening for overweight in chil- covariates were controlled (television dren and adolescents as a means of pre- viewing, physical activity, energy intake, venting adverse health outcomes (Grade I breastfeeding duration, birth order, house- recommendation).1 ■ FAST TRACK hold income, mother’s smoking, dietary Acknowledgements The number of restraint, and mother’s current BMI). The opinions and assertions contained herein are the Large for gestational age. A US nation- private view of the author and not to be construed as of- children 2 years fi cial or as refl ecting the view of the US Air Force Medi- al cohort study of 3192 children adjusted cal Service or the US Air Force at large. and older who are for gestational age, found that large- overweight has for-gestational-age (LGA) infants with References 1. US Preventive Services Task Force. Screening and tripled in the past birth weights above the 90th percentile interventions for childhood obesity. Guide to Clini- remained longer and heavier through 83 cal Preventive Services. Rockville, MD: Agency for Healthcare Research and Quality; 2005. 2 decades 5 months of life. The triceps and subscapu- 2. Krebs NF, Jacobson MS, and the American Acad- lar skinfold measurements at 3 years of emy of Pediatrics Committee on Nutrition. Preven- tion of pediatric overweight and obesity. Pediatrics. age for children born LGA were virtually 2003;112:424-430. identical to those of children born appro- 3. Parsons TJ, Power C, Logan S, et al. Childhood pre- dictors of adult obesity: a systematic review. Int J priate for gestational age, but by 6 years of Obes Relat Metab Disord. 1999;23(suppl 8):S1-S107. age, skinfold measurements had diverged 4. Gillman MW, Rifas-Shiman S, Berkey CS, et al. Ma- considerably, to more than 0.60 standard ternal , birth weight, and ado- lescent obesity. Pediatrics. 2003;111(3):e221-226. deviations. The researchers concluded 5. Hediger ML, Overpeck MD, McGlynn A, et al. that intrauterine growth is associated with Growth and fatness at three to six years of age of children born small- or large-for-gestational age. obesity in early childhood. Pediatrics. 1999;104:e33. Finally, a large Chinese population- 6. He Q, Ding ZY, Fong DY, et al. Risk factors of obe- sity in preschool children in China: a population- based, case-control study (N=1322), based case-control study. Int J Obes Relat Metab found birth weight above 4.0 kg to be a Disord. 2000;24:1528-1536. risk factor for obesity in preschool-age 7. Frisancho AR. Prenatal compared with paren- tal origins of adolescent fatness. Am J Clin Nutr. children (OR=3.77; 95% CI, 2.06-6.29).6 2000;72:1186-1190.

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