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Obesity Prevalence Among Low-Income, Preschool-Aged Children --- United States, 1998--2008

Childhood obesity continues to be a leading public health concern that disproportionately affects low-income and minority children (1). Children who are obese in their preschool years are more likely to be obese in adolescence and adulthood (2) and to develop diabetes, hypertension, hyperlipidemia, asthma, and sleep apnea (3). One of the Healthy People 2010 objectives (19-3) is to reduce to 5% the proportion of children and adolescents who are obese (4). CDC's Pediatric Nutrition Surveillance System (PedNSS) is the only source of nationally compiled obesity surveillance data obtained at the state and local level for low-income, preschool-aged children participating in federally funded health and nutrition programs. To describe progress in reducing childhood obesity, CDC examined trends and current prevalence in obesity using PedNSS data submitted by participating states, territories, and Indian tribal organizations during 1998--2008. The findings indicated that obesity prevalence among low-income, preschool-aged children increased steadily from 12.4% in 1998 to 14.5% in 2003, but subsequently remained essentially the same, with a 14.6% prevalence in 2008. Reducing childhood obesity will require effective prevention strategies that focus on environments and policies promoting physical activity and a healthy diet for families, child care centers, and communities.

PedNSS is a state-based surveillance system that monitors the nutritional status of children from birth through age 4 years enrolled in federally funded programs that serve low-income children. For all states except California and North Carolina, data come exclusively from the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC).* In California, data are exclusively from Medicaid-funded programs. North Carolina submits data from both WIC (95.5%) and non-WIC programs (4.5%). For the states included in this analysis, 21.0% of children aged 2--4 years are covered by PedNSS. On average, children are seen twice a year by the program; height and weight are measured each time. Data are collected at the clinic level and submitted to CDC for analysis. Federally funded programs submit data on weight, height (measured by trained staff using a standard protocol during clinic visits), age, sex, and the race/ethnicity reported by the child's parent or caregiver. CDC uses weight, height, and age data to calculate body mass index (BMI) (weight [kg] / height [m2]). For children aged 2--4 years, obesity is defined as BMI-for-age ≥95th percentile based on the 2000 CDC sex-specific growth charts (5). CDC performs routine edits to assess data quality. An error flag is applied to height or weight data that are either missing, miscoded, or biologically implausible (e.g., height-for-age z-score <-5.0 or >3.0, body mass index [BMI]-for-age [children aged ≥2 years] z-score <-4.0 or >5.0, weight-for-age z-score <-4.0 or >5.0, or BMI-for-age [children aged ≥2 years] z-score <-4.0 or >5.0). All flagged data are excluded from PedNSS analyses.

CDC randomly selected one record per child per year to estimate obesity prevalence in 1998, 2003, and 2008. To assess the change in obesity prevalence in PedNSS overall and by race/ethnicity, prevalence was estimated using data only from the subset of federally funded programs that participated in 1998, 2003, and 2008 (N = 37). The average annual change in obesity prevalence during 1998--2003 and 2003--2008 was estimated for each PedNSS program. If data for a program were unavailable for a given year but were available for the preceding or subsequent year, CDC substituted the data for the adjacent year and calculated the annual change to account for the shorter or longer period. Chi-square tests for difference in proportions were conducted across each period, and tests were statistically significant (p<0.05) unless otherwise noted in this report.

During 1998--2008, the number of federally funded programs reporting data to PedNSS varied from 43 to 52. In 2008, records on approximately 8 million children were submitted from 43 states, the District of Columbia, Puerto Rico, the U.S. Virgin Islands, and six Indian tribal organizations (Table). The overall prevalence of obesity among low-income, preschool-aged children increased from 12.4% (n = 1,999,970) in 1998 to 14.5% (n = 1,967,625) in 2003 and 14.6% (n = 2,222,410) in 2008 (Figure). Obesity prevalence increased 0.43 percentage points annually during 1998--2003, but only 0.02 percentage points annually during 2003--2008. Obesity increased across all racial/ethnic groups during 1998--2003, with the exception of Asian/Pacific Islander (A/PI) children. However, during 2003--2008, obesity remained stable among all groups except American Indian/Alaska Native (AI/AN) children. In 2008, prevalence was highest among AI/AN (21.2%) and Hispanic (18.5%) children, and lowest among non-Hispanic white (12.6%), non-Hispanic black (11.8%), and A/PI (12.3%) children.

In 2008, only programs in Colorado and Hawaii had obesity prevalences ≤10%. The two federally funded programs with prevalence >20% were Indian tribal organizations (Table). Of the 41 PedNSS programs supplying data for 1998--2003, a total of 38 (93%) reported an increase in obesity prevalence. In contrast, of the 44 programs supplying data for 2003--2008, 22 (50%) reported an increase in obesity, whereas 14 (32%) reported no change, and eight (18%) reported a decrease.

Reported by: AJ Sharma, PhD, LM Grummer-Strawn, PhD, K Dalenius, MPH, D Galuska, PhD, M Anandappa, MS, E Borland, H Mackintosh, MSPH, R Smith, MS, Div of Nutrition, Physical Activity and Obesity, National Center for Chronic Disease Prevention and Health Promotion, CDC.

Editorial Note:

Reduction of obesity among children and adolescents is a national priority in the United States (4). The results presented in this report indicate that among low-income, preschool-aged children participating in federally funded nutrition programs, the prevalence of obesity increased during 1998--2003, but stabilized during 2003--2008. In 2008, the national prevalence of obesity in this group remained highest among low-income Hispanic and AI/AN children and continued to increase among AI/AN children. These results suggest overall progress in stabilizing the prevalence of childhood obesity in a subset of low-income, preschool-aged children. However, these results should be confirmed through additional research using other data sets.

Children in preschool age groups are a priority for surveillance because obesity trends in this group can serve as a bellwether for trends in older children and adults (2). PedNSS currently serves as the only source of national obesity prevalence data compiled specifically on low-income, preschool-aged children. Because PedNSS nutritional data are dependent on enrollments in participating federally funded programs, PedNSS results are subject to variations in enrollment in these programs in each state. However, the effect of such variations on PedNSS results is difficult to determine. Conditions within a state that differentially affect the enrollment of children with varying prevalences of obesity could affect state or national results. In addition, changes in the proportion of children from each state might alter the results. For example, California, the largest data contributor to PedNSS, has one of the highest prevalences of obesity. The percentage of the total PedNSS sample provided by California decreased from 20.2% in 1998 to 13.6% in 2008. However, even deletion of all California data would not alter the overall results; an increase from 1998 to 2003 would still be observed, followed by stabilization through 2008. Furthermore, stabilization or declines were observed in half of the individual federally funded programs in PedNSS.

To maintain the consistency of PedNSS data, methods for data collection and recording are set nationally and are uniform across states and participating federal programs. The procedures for collecting height and weight data did not change during 1998--2008, with the exception of an increasing use of digital scales. Given the procedures within the WIC program for regular calibration of scales, this change should not affect rates of obesity. CDC has stringent requirements for data quality and uses standardized procedures for data cleaning; data files that do not meet these standards are rejected, as are records that do not meet standards for acceptable heights and weights.

The reason for the stabilization of overall obesity prevalence among these children during 2003--2008 is not known and likely is complex. One factor might be prevention efforts within state and local WIC programs targeting behaviors related to obesity in children. For example, certain initiatives in WIC§ have attempted to raise public awareness, acceptance, and support of breastfeeding, increased the percentage of low-fat or fat-free milk vouchers issued for children aged >2 years, and reduced television viewing (6). Recommendations such as those from the Institute of Medicine's Preventing Childhood Obesity report also might have spurred greater attention to obesity prevention for all children (7).

The National Health and Nutrition Examination Survey (NHANES) also has found a stabilization of obesity prevalence in U.S. children. NHANES found no significant increase in obesity prevalence during 1999--2006 in children aged 2--19 years (8). This apparent plateau remained even after adjusting for differences in prevalence by age group. Trends in the 2--5 year age group were not analyzed separately because of small sample size. For NHANES 2003--2006, the overall prevalence of obesity (BMI-for-age ≥95th percentile) for children aged 2--5 years was 12.4% (standard error = 1.0%), lower than the rates for both 2003 and 2008 described in this report.

The findings in this report are subject to at least three limitations. First, the proportion of children participating in federally funded nutrition programs increased during 1998--2008, as evidenced by the 11% increase in the number of children in these analyses (i.e., from 1,999,970 in 1998 to 2,222,410 in 2008). However, how the addition of these children might have affected the prevalence of obesity is unknown. Second, the percentage of the total PedNSS dataset that is made up of WIC records increased from 76% in 1998 to 85% in 2008. If the prevalence of obesity were lower in WIC than in non-WIC programs, this increase could partially explain the observed trends. However, when the analysis was conducted using only data from WIC, results were not substantially different. Finally, PedNSS data are not representative of all low-income, preschool-aged children in the United States because not all states participate in PedNSS and not all low-income children participate in federally funded programs.

Childhood obesity remains a serious public health problem even among this subset, particularly among AI/AN children. A sustained and effective public health response is necessary across the United States to reduce childhood obesity. Strategies should emphasize improving environments and policies that promote physical activity and a healthy diet.

References

  1. Wang Y, Beydoun MA. The obesity epidemic in the United States---gender, age, socioeconomic, racial/ethnic, and geographic characteristics: a systematic review and meta-regression analysis. Epidemiol Rev 2007;29:6--28.
  2. Serdula MK, Ivery D, Coates RJ, Freedman DS, Williamson DF, Byers T. Do obese children become obese adults? A review of the literature. Prev Med 1993;22:167--77.
  3. American Academy of Pediatrics. Policy statement: prevention of pediatric overweight and obesity. Pediatrics 2003;112:424--30.
  4. US Department of Health and Human Services. Healthy people 2010: objectives for improving health (part B: focus areas 15--28). 2nd ed. Washington, DC: US Department of Health and Human Services; 2000. Available at http://www.health.gov/healthypeople.
  5. Kuczmarski RJ, Ogden CL, Grummer-Strawn LM, et al. CDC growth charts: United States. Adv Data 2000;314:1--27. Available at http://www.cdc.gov/growthcharts.
  6. Johnson DB, Birkett D, Evens C, Pickering S. Statewide intervention to reduce television viewing in WIC clients and staff. Am J Health Promot 2005;19:418--21.
  7. Institute of Medicine. Preventing childhood obesity: health in the balance. Washington, DC: National Academies Press; 2005.
  8. Ogden CL, Carroll MD, Flegal KM. High body mass index for age among US children and adolescents, 2003--2006. JAMA 2008;299:2401--5.

* Eligibility criteria for WIC includes a family income ≤185% of the poverty income threshold, based on U.S. Poverty Income Guidelines, available at http://aspe.os.dhhs.gov/poverty. A person who participates or has family members who participate in certain other benefit programs, such as the Medicaid or Aid to Families with Dependent Children/Temporary Assistance to Needy Families, automatically meets the income-eligibility requirement.

Including the Early and Periodic Screening, Diagnosis, and Treatment Program, other Medicaid-funded child health programs, and Title V Maternal and Child Health Programs. Eligibility criteria includes a family income ≤200% of the poverty income threshold, based on U.S. Poverty Income Guidelines. The non-WIC records accounted for 24% of records in 1998, 19% in 2003, and 15% in 2008.

§ Additional information available at http://www.nal.usda.gov/wicworks/spotlight/bfweek_resources.html.

Additional information available at http://www.health.state.ny.us/prevention/nutrition/resources/docs/2003-2006_ewph_community_intervention_projects.pdf.

TABLE. Average annual change in obesity* prevalence among children aged 2--4 years, by state, territory, and Indian tribal organization --- Pediatric Nutrition Surveillance System, United States, 1998--2003 and 2003--2008

State, territory, or Indian tribal organization

Average percentage-point change per year

1998

2003

2008

No. of

children

Obesity

prevalence (%)

No. of

children

Obesity

prevalence (%)

No. of

children

Obesity

prevalence (%)

1998--2003

2003--2008

Alabama

39,998

11.7

30,221

14.7

56,813

13.8

0.50

-0.23

Arizona

51,279

9.7

67,618

12.4

75,338

14.6

0.45

0.55

Arkansas

34,968

9.7

31,625

12.2

38,591

13.9

0.50

0.34

California

398,222

15.5

344,384

17.6

301,643

17.3

0.42

-0.06

Colorado

---§

---

50,773

9.4

43,476

9.4

---

0.00**

Connecticut

23,272

17.8

22,495

19.6

25,623

15.5

0.36

-0.82

Florida

141,831

11.3

155,482

13.4

209,671

14.1

0.42

0.14

Georgia

87,823

9.4

92,728

12.4

124,533

14.8

0.60

0.48

Hawaii

3,649

10.3

15,602

10.1

16,106

9.3

-0.04**

-0.16

Idaho

15,121

9.8

16,340

11.2

20,081

12.3

0.28

0.22

Illinois

88,178

13.5

70,666

13.9

63,414

14.7

0.08

0.16

Indiana

64,411

10.5

51,953

13.7

66,499

14.5

0.64

0.16

Iowa

29,788

10.6

32,913

13.9

33,548

15.1

0.66

0.24

Kansas

22,628

8.8

27,076

12.6

34,352

13.3

0.76

0.14

Kentucky

48,075

12.1

60,984

17.2

62,832

15.7

1.02

-0.30

Louisiana

45,834

10.4

44,036

13.3

34,041

13.8

0.58

0.13

Maine

11,747

12.1

9,861

15.8

---

---

0.74

---

Maryland

23,329

12.0

42,884

14.4

54,866

15.7

0.40

0.33

Massachusetts

59,511

14.8

55,785

16.7

59,297

16.7

0.38

0.00**

Michigan

90,760

10.1

93,962

12.9

103,523

13.9

0.56

0.20

Minnesota

76,271

11.0

40,161

13.2

65,607

13.4

0.44

0.04**

Mississippi

11,850

13.2

---

---

44,807

14.6

---

---

Missouri

58,000

9.8

56,346

13.3

60,908

13.9

0.70

0.12

Montana

9,658

9.0

10,178

11.0

10,428

12.4

0.40

0.28

Nebraska

13,961

9.9

17,242

13.4

20,658

13.9

0.70

0.10**

Nevada

6,123

11.6

14,595

13.6

23,348

12.9

0.40

-0.14

New Hampshire

5,530

13.5

7,227

15.6

8,082

15.5

0.42

-0.02**

New Jersey

56,292

15.1

56,774

17.9

68,163

17.9

0.56

0.00**

New Mexico

17,523

7.6

27,555

9.7

22,295

12.0

0.42

0.46

New York

207,479

14.7

186,284

16.6

209,713

14.6

0.38

-0.40

North Carolina

80,956

11.1

75,206

14.5

96,381

15.7

0.68

0.24

North Dakota

7,246

9.4

6,097

11.6

6,551

13.8

0.44

0.44

Ohio

17,219

10.4

89,824

11.6

125,011

12.2

0.24

0.12

Oregon

34,546

11.9

29,875

14.7

49,193

14.7

0.56

0.00**

Pennsylvania

108,858

10.7

100,053

12.4

111,879

11.5

0.34

-0.18

Rhode Island

---

---

---

---

11,466

16.2

---

---

South Carolina

48,543

10.0

32,239

12.4

28,209

13.3

0.48

0.18

South Dakota

8,968

9.0

8,423

13.6

9,125

16.2

0.92

0.52

Tennessee

56,208

10.0

60,086

12.0

49,016

13.8

0.40

0.36

Texas

---

---

422,127

14.4

164,435

16.2

---

0.36

Utah

23,765

6.5

31,099

8.6

---

---

0.42

---

Vermont

6,225

11.6

8,504

13.1

7,009

13.3

0.30

0.04**

Virginia

---

---

20,238

18.5

59,627

19.0

---

0.10**

Washington

55,162

12.0

65,828

13.8

92,980

14.4

0.45

0.10

West Virginia

24,170

10.6

22,079

13.2

22,689

13.5

0.52

0.06**

Wisconsin

52,186

10.1

50,284

13.0

55,875

13.6

0.58

0.12

Wyoming

---

---

5,269

9.5

---

---

---

---

District of Columbia

6,499

10.9

5,926

13.3

6,195

13.3

0.48

0.00**

Puerto Rico

---

---

102,624

24.0

99,829

17.9

---

-1.22

U.S. Virgin Islands

---

---

---

---

2,339

13.6

---

---

Cheyenne River Sioux Tribe (SD)

362

22.1

388

17.5

423

18.4

-1.15**

0.18**

Chickasaw Nation (OK)

1,039

8.9

1,478

12.0

---

---

0.62

---

Inter Tribal Council of Arizona

4,680

19.8

5,037

20.9

5,823

23.5

0.22**

0.52

Navajo Nation

---

---

7,616

14.4

6,824

16.9

---

0.50

Rosebud Sioux Tribe (SD)

604

16.4

641

17.3

651

19.2

0.18**

0.38**

Standing Rock Sioux Tribe (ND)

---

---

422

20.1

541

25.0

---

0.98**

Three Affiliated Tribes (ND)

---

---

---

---

163

19.6

---

---

* Defined as body mass index (BMI)-for-age ≥95th percentile based on the 2000 CDC sex-specific growth charts, available at http://www.cdc.gov/growthcharts.

Data from subsequent year used.

§ Data not available.

Data from preceding year used.

** No significant change in obesity prevalence.

FIGURE. Change in obesity* prevalence during 1998--2003 and 2003--2008 among children aged 2--4 years, by race/ethnicity --- Pediatric Nutrition Surveillance System, United States, 1998--2008

The figure shows changes in obesity prevalence from the period 1998-2003 to the period 2003-2008 among U.S. children aged 2-4 years, by race/ethnicity, based on date from the Pediatric Nutrition Surveillance System. Overall, obesity prevalence among these low-income, preschool-aged children enrolled in federally funded nutrition programs increased steadily from 12.4% in 1998 to 14.5% in 2003, but subsequently remained essentially the same, with a 14.6% prevalence in 2008. Obesity increased across all racial/ethnic groups during 1998-2003, with the exception of Asian/Pacific Islander children. However, during 2003-2008, obesity remained stable among all groups except American Indian/Alaska Native children. In 2008, prevalence was highest among American Indian/Alaska Native (21.2%) and Hispanic (18.5%) children, and lowest among non-Hispanic white (12.6%), non-Hispanic black (11.8%), and Asian/Pacific Islander (12.3%) children.

* Defined as body mass index (BMI)-for-age ≥95th percentile based on the 2000 CDC sex-specific growth charts, available at http://www.cdc.gov/growthcharts.

Includes only the 37 federally funded programs that provided data in 1998, 2003, and 2008.

§ Sample sizes in 2008 were as follows: total, 2,222,410; non-Hispanic white, 845,910; non-Hispanic black, 438,645; Hispanic, 749,109; American Indian/Alaska Native, 23,960; and Asian/Pacific Islander, 68,933.

Alternative Text: The figure above shows changes in obesity prevalence from the period 1998-2003 to the period 2003-2008 among U.S. children aged 2-4 years, by race/ethnicity, based on date from the Pediatric Nutrition Surveillance System. Overall, obesity prevalence among these low-income, preschool-aged children enrolled in federally funded nutrition programs increased steadily from 12.4% in 1998 to 14.5% in 2003, but subsequently remained essentially the same, with a 14.6% prevalence in 2008. Obesity increased across all racial/ethnic groups during 1998-2003, with the exception of Asian/Pacific Islander children. However, during 2003-2008, obesity remained stable among all groups except American Indian/Alaska Native children. In 2008, prevalence was highest among American Indian/Alaska Native (21.2%) and Hispanic (18.5%) children, and lowest among non-Hispanic white (12.6%), non-Hispanic black (11.8%), and Asian/Pacific Islander (12.3%) children.

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Date last reviewed: 7/23/2009

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