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

Nichols, William

Persons, Robert K.

Sevdy, Tristan L.

University of Missouri: MOspace

CLINICAL INQUIRIES Evidence Based Answers from the Family Physicians Inquiries NetworkCopy for evidence-based answerEvidence-based answerClinical commentary VOL 57, NO 6 / JUNE 2008 409www.jfponline.comFAST TRACK  Does birth weight predict childhood obesity?Yes. A birth weight greater than 4,000 g is associated with an increased risk of obesity in both childhood and adolescence (strength of recommendation [SOR]: B, systematic review and multiple cohort studies). Lifestyle matters, tooFew people have more questions than brand-new parents. Physicians often answer these inquiries from their pool of clinical experience or pearls handed down by mentors. It’s refreshing to be able to address a parental query on the basis of good evidence rather than empiricism.  The data compel us to inform parents that a new baby who weighs more than 4 kg is at increased risk of childhood obesity. However, all parents should be counseled that the lifestyle choices they make for their child are far more likely than birth weight to infl uence future obesity. Education about appropriate diet and physical activity is the bedrock from which to attack the childhood obesity epidemic. David Krulak, MD, MPHCamp Lejeune, NCClinical commentary❚ Evidence summaryThe number of children 2 years and older who are overweight has tripled in the past 2 decades; the current prevalence of over-weight children and adolescents in the US is 15%.1 By contrast with adults—in whom overweight and obesity are defi ned separately as a body mass index (BMI) above 25 kg/m2 and 30 kg/m2, respec-tively—overweight and obesity are syn-onymous in children and are defi ned as a BMI above the 95th percentile for age and sex.2 Children and adolescents with a BMI between the 85th and 95th percentiles are considered at risk for overweight.2 Overweight children are vulnerable to adverse health outcomes, including insulin resistance, hyperlipidemia, hyper-tension, depression, sleep apnea, asthma, steatohepatitis, genu varum, and slipped capital femoral epiphysis.2 The many vari-ables that have been suggested to infl uence childhood obesity include birth weight, gestational age, parental obesity, socioeco-nomic status, single parent household, and birth order.3-5Birth weight and later BMI: Consistently linkedA systematic review of 19 longitudinal, ob-servational studies comparing birth weight with later BMI indicates that the associa-tion between the 2 is positive and consis-tent in multiple cohorts.3 Eleven studies fo-cused on outcomes in childhood; another 8 measured outcomes into adulthood. Fifteen of the 19 studies (79%), rang-ing in size from 1028 to 92,940 subjects, A birth weight >4,000 g heightens the risk of obesity in childhood and adolescenceRobert K Persons, DO, and Tristan L. Sevdy, MD, FAAFPEglin Family Medicine Residency, Eglin Air Force Base, FlaWilliam Nichols, MLS Eglin Air Force Base, Fla409_JFP0608   409 5/20/08   1:05:03 PMCopyright® Dowden Health Media  For personal use onlyFor mass reproduction, content licensing and permissions contact Dowden Health Media.FAST TRACKCLINICAL INQUIRIES410 VOL 57, NO 6 / JUNE 2008  THE JOURNAL OF FAMILY PRACTICEfound a positive association between birth weight and later BMI. However, the data were too heterogeneous to com-bine into a single summary measure. One representative study quantifi ed the rela-tive risk (RR) for severe obesity (>95th percentile BMI) at 5 years of age as 1.7 (95% confi dence interval [CI], 1.2-2.9) for birth weights between the 85th and 94th percentiles and 1.8 (95% CI, 1.1-2.9) for birth weights greater than the 95th percentile.3 Studies that didn’t fi nd such an association had smaller sample sizes (137 to 432 subjects) and, therefore, may have lacked the power to detect an association. Gestational diabetes. A subsequent retrospective cohort survey of 14,881 children born to mothers with gestational diabetes—and controlled for age, sex, and Tanner stage—found that the odds ratio (OR) for adolescent overweight was 1.4 (95% CI, 1.2-1.6) for each 1-kg increment in birth weight.4 The correlation persisted (OR=1.3; 95% CI, 1.1-1.5) when other covariates were controlled (television viewing, physical activity, energy intake, breastfeeding duration, birth order, house-hold income, mother’s smoking, dietary restraint, and mother’s current BMI).Large for gestational age. A US nation-al cohort study of 3192 children adjusted for gestational age, found that large-for-gestational-age (LGA) infants with birth weights above the 90th percentile remained longer and heavier through 83 months of life.5 The triceps and subscapu-lar skinfold measurements at 3 years of age for children born LGA were virtually identical to those of children born appro-priate for gestational age, but by 6 years of age, skinfold measurements had diverged considerably, to more than 0.60 standard deviations. The researchers concluded that intrauterine growth is associated with obesity in early childhood.Finally, a large Chinese population-based, case-control study (N=1322), found birth weight above 4.0 kg to be a risk factor for obesity in preschool-age children (OR=3.77; 95% CI, 2.06-6.29).6 The absolute rate of overweight increased from 8% to 26% among LGA infants.In adolescence, parental weight may be a factorA prospective cohort study of 1993 white LGA infants found a greater propensity to become obese in adolescence, but only if their mothers or fathers were also obese (RR=5.7).7 Children with lean parents did not have an increased risk of being over-weight in adolescence.RecommendationsAlthough major organizations don’t fo-cus on infant birth weight as a predictor of overweight, they do address childhood obesity. The American Academy of Pedi-atrics states that genetic, environmental, or combinations of risk factors predispos-ing children to obesity can and should be identifi ed.2 The US Preventive Services Task Force concludes that the evidence is insuffi cient to recommend for or against routine screening for overweight in chil-dren and adolescents as a means of pre-venting adverse health outcomes (Grade I recommendation).1 ■AcknowledgementsThe opinions and assertions contained herein are the private view of the author and not to be construed as of-fi cial or as refl ecting the view of the US Air Force Medi-cal Service or the US Air Force at large. References  1.  US Preventive Services Task Force. Screening and interventions for childhood obesity. Guide to Clini-cal Preventive Services. Rockville, MD: Agency for Healthcare Research and Quality; 2005.  2.  Krebs NF, Jacobson MS, and the American Acad-emy of Pediatrics Committee on Nutrition. Preven-tion of pediatric overweight and obesity. Pediatrics. 2003;112:424-430.  3.  Parsons TJ, Power C, Logan S, et al. Childhood pre-dictors of adult obesity: a systematic review. Int J Obes Relat Metab Disord. 1999;23(suppl 8):S1-S107.  4.  Gillman MW, Rifas-Shiman S, Berkey CS, et al. Ma-ternal gestational diabetes, birth weight, and ado-lescent obesity. Pediatrics. 2003;111(3):e221-226.  5.  Hediger ML, Overpeck MD, McGlynn A, et al. Growth and fatness at three to six years of age of children born small- or large-for-gestational age. Pediatrics. 1999;104:e33.  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. Int J Obes Relat Metab Disord. 2000;24:1528-1536.  7.  Frisancho AR. Prenatal compared with paren-tal origins of adolescent fatness. Am J Clin Nutr. 2000;72:1186-1190. The number of children 2 years and older who are overweight has tripled in the past 2 decades 410_JFP0608   410 5/20/08   1:05:07 PM

Does birth weight predict childhood obesity?

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