2
Descriptive Epidemiology and Trends

The committee began its reexamination of the Institute of Medicine (IOM) (1990) recommendations for weight gain during pregnancy by evaluating trends since 1990 in both prepregnancy maternal body mass index (BMI) and gestational weight gain (GWG). As described in detail in Chapter 3, prepregnancy BMI and GWG are interrelated. When evaluating trends in GWG, the committee considered whether women were gaining weight within the ranges recommended in the IOM (1990) report. The committee also evaluated trends since 1990 in postpartum weight retention.

The committee then examined trends since 1990 in key weight-related sociodemographic maternal characteristics and pregnancy outcomes (i.e., characteristics and outcomes known to be associated with prepregnancy BMI and/or GWG). Weight-related pregnancy outcomes include both maternal and child health outcomes.

This chapter summarizes the committee’s evaluation of these two areas of descriptive epidemiology. This information provides a context for understanding the sociodemographic and behavioral environment that may influence successful promotion of healthy GWG and optimal pregnancy outcomes.

TRENDS IN MATERNAL WEIGHT AND GESTATIONAL WEIGHT GAIN

Maternal Body Mass Index

One of the most serious issues that practitioners and scientists have faced in the past 30 years is the increase in prevalence of overweight and



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2 Descriptive Epidemiology and Trends The committee began its reexamination of the Institute of Medicine (IOM) (1990) recommendations for weight gain during pregnancy by evaluating trends since 1990 in both prepregnancy maternal body mass index (BMI) and gestational weight gain (GWG). As described in detail in Chapter 3, prepregnancy BMI and GWG are interrelated. When evaluating trends in GWG, the committee considered whether women were gaining weight within the ranges recommended in the IOM (1990) report. The com- mittee also evaluated trends since 1990 in postpartum weight retention. The committee then examined trends since 1990 in key weight-related sociodemographic maternal characteristics and pregnancy outcomes (i.e., characteristics and outcomes known to be associated with prepregnancy BMI and/or GWG). Weight-related pregnancy outcomes include both ma- ternal and child health outcomes. This chapter summarizes the committee’s evaluation of these two areas of descriptive epidemiology. This information provides a context for un- derstanding the sociodemographic and behavioral environment that may influence successful promotion of healthy GWG and optimal pregnancy outcomes. TRENDS IN MATERNAL WEIGHT AND GESTATIONAL WEIGHT GAIN Maternal Body Mass Index One of the most serious issues that practitioners and scientists have faced in the past 30 years is the increase in prevalence of overweight and 

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 WEIGHT GAIN DURING PREGNANCY TABLE 2-1 Distribution of BMI (World Health Organization categories) from 1976 to 2004 Among U.S. Nonpregnant Women 12 to 44 Years of Age by Race or Ethnicity and Age (percentage) 1976-1980 1988-1994 1999-2004 Total (%) Underweight 6.0 4.4 3.5 Normal weight 62.1 53.4 41.1 Overweight 18.8 20.8 25.3 Class I obese 7.9 12.2 15.8 Class II obese 3.5 6.0 7.7 Class III obese 1.7 3.4 6.5 By Race or Ethnicity Non-Hispanic white (%) Underweight 6.3 4.7 4.3 Normal weight 64.2 58.3 46.4 Overweight 17.9 18.4 23.3 Class I obese 7.2 10.5 13.8 Class II obese 2.9 5.3 6.9 Class III obese 1.5 2.8 5.3 Non-Hispanic black (%) —a Underweight 3.9 2.7 Normal weight 47.8 37.3 23.4 Overweight 24.4 27.7 25.7 Class I obese 13.3 15.8 23.7 Class II obese 7.3 9.7 12.2 —a Class III obese 6.8 13.3 obesity among American women of childbearing age (Flegal et al., 1998; Mokdad et al., 1999; IOM, 2005; Kim et al., 2007). The prevalence of obesity in women 12 to 44 years of age has more than doubled since 1976 (Table 2-1). Data collected by the National Center for Health Statistics (NCHS) in 1999-2004 showed that nearly two-thirds of women of child- bearing age were classified as overweight (as defined by BMI ≥ 25 kg/m2), and almost one-third were obese (BMI ≥ 30 kg/m2) (personal communica- tion, A. Branum, Centers for Disease Control and Prevention [CDC], De- cember 2008). Obesity is far more common among racial or ethnic minority groups and increases in prevalence with advancing age.

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 DESCRIPTIVE EPIDEMIOLOGY AND TRENDS 1976-1980 1988-1994 1999-2004 Mexican American (%) —b —a Underweight 1.9 —b Normal weight 36.0 32.0 —b Overweight 32.3 32.6 —b Class I obese 18.1 19.6 Class II obese 6.9 7.9 Class III obese 4.7 6.7 By Age Age 20-34 (%) Underweight 7.1 5.1 4.6 Normal weight 64.9 58.3 44.2 Overweight 16.8 18.2 23.9 Class I obese 6.9 10.6 14.8 Class II obese 3.0 5.2 7.1 Class III obese 1.4 2.6 5.4 Age 35-44 (%) Underweight 3.8 3.3 2.1 Normal weight 55.7 46.8 37.3 Overweight 23.2 24.2 27.1 Class I obese 10.2 14.2 17.1 Class II obese 4.8 7.0 8.6 —a Class III obese 4.4 7.9 NOTE: Underweight, < 18.5 kg/m2; normal, 18.5 to < 25.0 kg/m2; overweight, 25.0 to < 30.0 kg/m2; class I obese, 30.0 to < 35.0 kg/m2; class II obese, 35.0 to < 40 kg/m2; class III obese, ≥ 40 kg/m2. aInsufficient unweighted data to make reliable estimates. bHispanic ethnicity not available in 1976-1980 National Health and Nutrition Examination Survey (NHANES). SOURCE: Personal communication, A. Branum, CDC, Hyattsville, Maryland, December 2, 2008. Importantly, the prevalence of severe obesity, once a relatively rare condition, has increased dramatically among women of childbearing age (Table 2-1). Between 1979 and 2004, class I and II obesity doubled and class III obesity tripled. Trends are similar by age. The prevalence of all classes of obesity is lowest in white non-Hispanic women and highest in non-Hispanic black women; among the latter, the prevalence of class I obesity approaches 25 percent, and the prevalence of class II and III obesity each exceeds 10 percent. Almost one-fifth of Hispanic women have class I obesity, with the proportions of class II and III obesity each approaching 10 percent.

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 WEIGHT GAIN DURING PREGNANCY Because of these trends, more women are already obese when they become pregnant. Based on data from the Pregnancy Risk Assessment Monitoring System (PRAMS), one-fifth of American women are obese (BMI > 29 kg/m2) at the start of pregnancy, a figure that has risen 70 percent in the past decade (Kim et al., 2007) (Figure 2-1). More specifically, although the prevalence of overweight has increased only slightly in the population as a whole and among black and white women, the prevalence of obesity doubled in white women and increased by 50 percent in black women. These statistics are based on data from only nine states; no nationally representative data are available from a modern cohort to provide trends in pregravid BMI values. Body Mass Index Classification The report Nutrition During Pregnancy (IOM, 1990) recommended the use of BMI to classify maternal prepregnancy weight. The four prepreg- nancy BMI categories used in that report were selected to be consistent with 90 percent, 120 percent, and 135 percent of the 1959 Metropolitan Life Insurance Company’s ideal weight-for-height standards—the standard most Underweight Normal Weight Overweight Obese 2002-2003 Total 1998 1993-1994 White 2002-2003 1998 1993-1994 Black 2002-2003 1998 1993-94 0 10 20 30 40 50 60 70 80 90 100 Percent of Women in Total Population FIGURE 2-1 Trends in the distribution of BMIa from 1993 to 2003 among prepreg- nant U.S. women in the total population and by race or ethnicity. Figure 2-1.eps aIOM BMI categories were used (underweight, < 19.8 kg/m2; normal weight, 19.8-26.0 kg/m2; overweight, 26.1-29.0 kg/m2; obese, > 29 kg/m2). SOURCE: Kim et al., 2007.

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 DESCRIPTIVE EPIDEMIOLOGY AND TRENDS commonly used in the United States when the report was written. Since then, the World Health Organization (WHO, 1998) has developed and the National Heart, Lung, and Blood Institute (NHLBI, 1998) has adopted the use of new BMI categories. The WHO BMI categories are based on differ- ent considerations and, as a result, are defined differently than those in the IOM (1990) report. The WHO BMI categories also include several grades or categories of obesity (see Table 2-2). The weight gain categories identified in IOM (1990) classify more women as underweight than the more stringent WHO cutoff point, while the WHO categories classify more women as overweight and fewer women as obese, with similar differences by race or ethnicity and age. In 1999- 2004, with either the IOM or WHO cutoff points, about half of women are overweight (BMI > 26 with IOM cutoff point or > 25 with WHO cutoff point) (Figure 2-2). Gestational Weight Gain Assessment of both prepregnant BMI and GWG requires rigorous methods of data collection (see Table 2-3). Unfortunately, most of the data available to the committee were not collected with a high level of rigor, and most studies relied on recalled weight values (see Table 2-4). Although the IOM (1990) report called for collection of national data on GWG, pre- pregnancy height, and weight for proper surveillance, today there are still no nationally representative data with which to study trends in GWG in the United States. The committee used three sets of data for its evaluation of GWG: birth certificate, PRAMS, and Pregnancy Nutrition Surveillance System (PNSS) data. The latter two datasets (see Appendix A for descrip- tions) also provided information on prepregnant BMI. Data Obtained from Birth Certificates Data obtained by standard U.S. birth certificates from 49 states il- lustrate that from 1990 to 2005 reported weight gains among singleton TABLE 2-2 Comparison of Institute of Medicine (IOM) and World Health Organization (WHO) BMI Categories Category IOM WHO < 19.8 < 18.5 kg/m2 kg/m2 Underweight 19.8-26 kg/m2 18.5-24.9 kg/m2 Normal weight 26.1-29 kg/m2 25-29.9 kg/m2 Overweight > 29 kg/m2 30-34.9 kg/m2 Obese Class I 35-39.9 kg/m2 Obese Class II — ≥ 40 kg/m2 Obese Class III —

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0 WEIGHT GAIN DURING PREGNANCY Underweight Normal Weight Overweight Obese 55 48.4 47.4 50 45 40 35 29.7 Percent 26.5 30 22.8 25 15 20 15 6.9 10 3.3 5 0 IOM NHLBI FIGURE 2-2 Distribution of BMI from 1999 to 2004 among U.S. nonpregnant women 12 to 44 years of age using the IOMa (1990) and the WHOb BMI cutoff points. Figure 2-2.eps (1990) BMI categories are underweight, < 19.8 kg/m2; normal, 19.8-26.0 kg/m2; aIOM overweight, 26.1-29.0 kg/m2; obese, > 29 kg/m2. bWHO BMI categories are underweight, < 18.5 kg/m2; normal, 18.5-24.9 kg/m2; over- weight, 25.0-29.9 kg/m2; obese, ≥ 30 kg/m2. SOURCE: Personal communication, A. Branum, CDC, Hyattsville, Maryland, April 15, 2008. pregnancy mothers of term, of 40 pounds both increased (Figure 2-3). Weight gain within the broad recommended range (16 to 40 pounds) (IOM, 1990) declined slowly during this 15-year period. Unfortu- nately, the standard birth certificate lacks data on maternal prepregnancy weight and height. Thus, data from this source cannot provide information about GWG relative to prepregnant BMI category. Additionally, the data on prepregnancy weight was self-reported and therefore more variable than clinical measures. The loss in precision and the degree of bias due to self- reporting must be taken into account when interpreting those data. There were some important differences in low and high gains among women in the different racial/ethnic and age groups. Specifically, the great- est increase in the proportion of women with a weight gain > 40 pounds from 1990 to 2005 was among white women (Figure 2-4). In 2005, ado- lescents (< 20 years old) were more likely to gain excessive weight during

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 DESCRIPTIVE EPIDEMIOLOGY AND TRENDS TABLE 2-3 Data Required to Assess Trends in Pregnancy-Related Maternal Weight and the Ideal and Practical Methods of Measurement and Acquisition Method of Measurement and Acquisition Required Data Ideal Practical Measureda Prepregnancy weight at a Recalled at the first prenatal visit preconceptional visit using a standardized question Measureda at the first prenatal Prepregnancy height visit Gestational weight Total gain: last measured Total gain: maternal recall of last gain available weight abstracted available weight from clinical records Pattern of gain: requires trimester-specific or midpregnancy weight abstractions Gestational age at Abstracted from clinical last available weightb records Postpartum weight Total retention: measured Total retention: recalled maternal maternal weight abstracted postpartum weight from clinical records Cross-sectionally in nonpregnant Measured longitudinally in women nonpregnant women Time: 3, 6, 9, 12, or 18 months Time: serial measurements 3, after delivery 6, 9, 12, and 18 months after delivery aAllweight and height measurements should be performed in light clothing without shoes. bThe gestational age at delivery may vary substantially from the gestational age at the last prenatal visit. Thus, misclassification may result if the gestational age at delivery is used in combination with weight at the last prenatal visit to determine weight gain adequacy. pregnancy than women 35 years of age and older. Between 1990 and 2005, there was a 31 percent increase in GWG of at least 40 pounds in singleton pregnancies among adolescents (NCHS, 2007a). In 2005, weight gain of < 15 pounds was more common among black and Hispanic than among white women (Figure 2-5). Within each racial or ethnic group, the propor- tion of women with low gains increased with advancing age. Weight Gain Relatie to Prepregnancy BMI Unfortunately, the standard birth certificate lacks data on maternal prepregnancy weight and height. Thus, data from this source cannot pro-

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TABLE 2-4 National Data Sources for Maternal Weight and Their Methods of Acquiring Key Variables  Prepregnancy Gestational Weight Data Source Weight Prepregnancy Height Gain Postpartum Weight Data Coverage Ideal Recalled weight at Measured height at Last recorded weight Measured weight at 50 states, little to no first prenatal visit first prenatal visit is abstracted from least once starting missing data is abstracted from is abstracted from clinical records 3 months or more clinical records clinical records postpartum Standard U.S. birth Not available Not available Recalled at delivery Not applicable 49 states (excludes certificate California) Revised 2003 U.S. Recalled at delivery Recalled at delivery Based on last Not applicable 19 states in 2006 birth certificate recorded weight abstracted from the medical record PRAMS Recalled at 2-4 Recalled at 2-4 Obtained from birth Not available 8 states months postpartum months postpartum certificates (recalled at delivery) PNSS Recalled at the Measured at the Recalled at the Measured at Low-income women in prenatal visit or prenatal visit or postpartum visit WIC postpartum 26 states postpartum visit postpartum visit recertification visit IFPS II Recalled in the Recalled in the Recalled in the Recalled at 3, 6, 9, Nationally distributed postpartum period postpartum period postpartum period and 12 months consumer opinion panel NOTE: IFPS II = Infant Feeding Practices Study II; PNSS = Pregnancy Nutrition Surveillance System; WIC = Special Supplemental Nutrition Program for Women, Infants, and Children.

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 DESCRIPTIVE EPIDEMIOLOGY AND TRENDS FIGURE 2-3 Weight gain during pregnancy for singleton term births in the United States, 1990-2005. Figure 2-3.eps NOTES: California does not report weight gain in pregnancy. Term is ≥ 37 weeks’ gestation. SOURCE: NCHS, 2007a. vide information about GWG relative to prepregnant BMI category. Birth certificate data may yield more useful statistics for weight gain surveillance in the near future. The IOM (1990) report called for collection of maternal prepregnancy weight and height, and these fields were added to the 2003 revised U.S. birth certificate, and by 2006, 19 states were using the revised birth certificate. At present, the two large surveillance systems collecting data on GWG and prepregnancy BMI in the United States, PRAMS and PNSS, permit identification of trends in recommended weight gains, although neither system is nationally representative. For PRAMS, GWG is taken from the birth certificate and other data are either pulled from medical records or are provided by maternal recall. Data Obtained from PRAMS PRAMS collects GWG data from birth certificates, and maternal pre- pregnancy height and weight are obtained from maternal interview in the

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 WEIGHT GAIN DURING PREGNANCY 25 1990 2000 20 2005 15 Percent 10 5 0 Non-Hispanic Non-Hispanic Hispanic Total White Black Population Group FIGURE 2-4 Percentage of women in the United States who gained more than 40 pounds during pregnancy, by race or ethnicity of the mother, 1990, 2000, and 2005. Figure 2-4.eps NOTES: Includes only mothers with a singleton delivery and only non-Hispanic white, non-Hispanic black, and Hispanic mothers (who might be of any race). The total number of women who gained > 40 pounds was 456,678 in 1990, 588,253 in 2000, and 656,363 in 2005. SOURCE: CDC, 2008a. 20 < 20 yrs 20-34 yrs 15 ≥ 35 yrs Percent 10 5 0 Total Non-Hispanic Non-Hispanic Hispanic White Black Population Group FIGURE 2-5 Percentage of women in the United States who gained less than 15 pounds during pregnancy by age and race or ethnicity of the mother, 2005. Figure 2-5.eps NOTES: Includes only mothers with a term (≥ 37 weeks’ gestation), singleton in- fant; excludes data for California. SOURCE: CDC, 2008b.

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 DESCRIPTIVE EPIDEMIOLOGY AND TRENDS postpartum period. Currently, 37 states, New York City and the Yankton Sioux Tribe (South Dakota) participate in PRAMS (available online at http://www.cdc.gov/prams/ [accessed February 5, 2009]). For the analysis of trends in GWG reported here, data were limited to the eight PRAMS states with at least 70 percent response rates and to women with complete data on prepregnancy BMI and singleton, term pregnancies (Alabama, Arkansas, Florida, Maine, New York [excludes New York City], Oklahoma, South Carolina, and West Virginia). Limitations in the dataset, including self- reported weight, were considered. In 2002-2003, PRAMS data indicate that the mean GWG was highest in underweight and normal weight women and declined in overweight and obese women among all racial/ethnic groups (Figure 2-6). The mean GWG among underweight and normal weight women in all racial/ethnic groups was within the recommended range but was higher than recommended for overweight women. For obese women, average weight gains were well 40 Underweight Overweight Normal Weight Obese 35 30 Weight Gain (lb) 25 20 15 10 5 0 All Women White Black Hispanic Population Group FIGURE 2-6 Mean gestational weight gain by BMI category and race or ethnicity, Pregnancy Risk Assessment Monitoring System, 2002-2003. NOTE: WHO BMI categories were used (underweight, < 18.5 kg/m2; normal, 18.5- Figure 2-6.eps 24.9 kg/m2; overweight, 25.0-29.9 kg/m2; obese, ≥ 30 kg/m2). SOURCE: Information contributed to the committee in consultation with P. Dietz, CDC, Atlanta, Georgia, January 2009.

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0 WEIGHT GAIN DURING PREGNANCY TABLE 2-7 Estimates of LGA by Sex, Race or Ethnicity, and Year: United States 1990 1995 2000 2005 Males Total 11.1 10.7 10.7 9.4 Non-Hispanic white 12.4 12.1 12.2 10.7 Non-Hispanic black 7.5 7.2 6.9 6.2 Hispanic 10.2 9.8 9.9 8.9 White 12.0 11.6 11.6 10.2 Black 7.5 7.2 7.0 6.4 American Indian/Alaska Native 13.8 13.6 13.2 12.0 Asian/Pacific Islander 6.5 6.2 6.1 5.4 Females Total 10.5 10.3 10.4 9.1 Non-Hispanic white 11.7 11.6 12.1 10.2 Non-Hispanic black 7.1 6.8 6.8 5.9 Hispanic 9.9 9.7 10.0 9.0 White 11.3 11.2 11.3 9.8 Black 7.1 6.8 6.8 6.1 American Indian/Alaska Native 14.3 13.5 13.5 12.8 Asian/Pacific Islander 6.8 6.6 6.4 5.7 NOTE: Singleton births only. SOURCE: CDC/NCHS, National Vital Statistics System, available online at http://www.cdc. gov/nchs/VitalStats.htm [accessed February 12, 2009]. Preterm Birth In 2005, 12.5 percent of all births were delivered preterm. The preterm birth rate has increased 20 percent since 1990 and 9 percent since 2000 (Figure 2-25). The greatest increase has been among late preterm births, those occurring at 34-36 weeks’ gestation, which have climbed 25 percent since 1990. The preterm birth rate for singleton gestations increased 13 percent from 1990 to 2005, again with late preterm births accounting for a majority of the increase. An increase in the rates of cesarean deliveries and induced births contributes to but does not completely explain this trend in late preterm births (March of Dimes, available online at http://www. marchofdimes.com/files/MP_Late_Preterm_Birth-Every_Week_Matters _3-24-06.pdf [accessed January 14, 2009]). There is a striking racial disparity in the rate of preterm birth (Fig- ure 2-26). Since 1990, the preterm birth rate increased 38 percent for non- Hispanic whites and 10 percent for Hispanic births; it decreased among non-Hispanic black mothers through most of the 1990s although it is up 12 percent since 2000. Over the past 15 years, non-Hispanic black women have been about twice as likely as non-Hispanic white women to deliver before 37 weeks’ gestation.

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 DESCRIPTIVE EPIDEMIOLOGY AND TRENDS 15 Less than 34 weeks 34-36 weeks 12.7 11.6 12 11.0 10.6 10.1 9.7 9 9.1 Percent 8.2 7.3 8.1 7.3 6.8 6 3 3.6 3.4 3.3 2.9 2.9 2.8 0 2005 1990 2000 2005 1990 2000 Year Year All Pluralities Singletons FIGURE 2-25 Preterm birth rates for all births and for singletons only: United States, 1990, 2000, and 2005. Figure 2-25.eps SOURCE: NCHS, 2007a. Non-Hispanic White Non-Hispanic Black Hispanic 20 18 16 Percent of Live Births Preterm 14 12 10 8 6 4 2 0 1990 1992 1994 1996 1998 2000 2002 2004 FIGURE 2-26 Trends in preterm live births in the United States by race, 1990 to 2005. Figure 2-26.eps NOTE: Preterm is defined as an infant born before 37 weeks of gestation. SOURCE: NCHS, 2007a.

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 WEIGHT GAIN DURING PREGNANCY Breastfeeding Analysis of data from the Ross Laboratories Mothers Survey, a large, national survey (Ryan et al., 2002), shows that the rates of breastfeeding initiation (in-hospital) and breastfeeding at 6 months rose by 16 percent and 14 percent, respectively, in the 1990s. In 2001, rates were at their highest point in 40 years (Figures 2-27 and 2-28). Recent data from the National Immunization Survey, a population-based survey conducted by the CDC, showed that these rates continued to rise from 2000 to 2004. There are remarkable disparities in rates of breastfeeding. Mothers who were white or Hispanic, older, college-educated, and not enrolled in WIC were significantly more likely to breastfeed and exclusively breastfeed in the hospital and at 6 months (Ryan et al., 2002). Childhood Obesity Nationally representative data show continuous increases in obesity (BMI ≥ 95th percentile) among American school-aged children and ado- lescents from 1980 to the present (available online at http://www.cdc. 80 69.5% 70 61.9% 60 51.5% Any breastfeeding 46.3% Percent 50 in-hospital 55.0% 40 43.5% 24.7% Exclusive 30 breastfeeding in-hospital 20 21.7% 10 65 68 71 74 77 80 83 86 89 92 95 98 01 Year FIGURE 2-27 In-hospital breastfeeding and exclusive breastfeeding rates, 1965- 2001. SOURCE: Ryan et al., 2002. Reproduced with2-27.epsfrom Pediatrics, Vol. 110, Figure permission pp. 1103-1109. Copyright © 2002 by the AAP.

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 DESCRIPTIVE EPIDEMIOLOGY AND TRENDS 50 40 32.5% Any breastfeeding 30 27.1% Percent at 6 months 17.6% 20 19.8% 17.2% 10 10.4% 5.4% Exclusive breastfeeding at 6 months 3.2% 0 71 74 77 80 83 86 89 92 95 98 01 Year FIGURE 2-28 Breastfeeding and exclusive breastfeeding rates at 6 months of age, 1971-2001. Figure 2-28.eps SOURCE: Ryan et al., 2002. Reproduced with permission from Pediatrics, Vol. 110, pp. 1103-1109. Copyright © 2002 by the AAP. gov/nccdphp/dnpa/obesity/childhood/prevalence.htm [accessed April 15, 2009]) (Figure 2-29). Recent data suggest that this trend may be slow- ing (Ogden et al., 2008). Population estimates from 2003 through 2006 suggest that almost a third of 2-19 year olds were at or above the 85th BMI percentile for sex and age (Ogden et al., 2008). Of these, 16 percent were above the 95th percentile, well above the Healthy People 00 goal of 5 percent, and 11.3 percent were above 97th percentile (rates of high BMI varied by age and race/ethnicity). Non-Hispanic black adolescents have a dramatically greater prevalence of overweight compared to non- Hispanic whites; Mexican American girls also have somewhat higher rates (Table 2-8).

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 WEIGHT GAIN DURING PREGNANCY Proportion of Children (%) Year of Survey FIGURE 2-29 Prevalence of obesity (≥ 95th percentile) among children and adoles- cents, United States, collected from 1963-2004, and reported from 1965-2006. SOURCES: Ogden et al., 2006, 2008. TABLE 2-8 Prevalence of4-29 BMI by Age Among U.S. Adolescent Figure 2-29 revised High Girls (12-19 years of age), 2003-2006 BMI Percentile of Non-Hispanic Black Mexican American Non-Hispanic White CDC Growth Charts % (SE) % (SE) % (SE) ≥ 85th 44.5 (1.5) 37.1 (1.9) 31.7 (1.9) ≥ 95th 27.7 (1.9) 19.9 (1.4) 14.5 (2.0) ≥ 97th 19.6 (1.5) 14.1 (1.3) 9.1 (1.6) NOTE: SE = standard error. SOURCE: Odgen et al., 2008. FINDINGS AND RECOMMENDATIONS Findings 1. Since the release of the weight gain recommendations of IOM (1990): • there has been a striking increase in the prevalence of maternal overweight and obesity, particularly among black, Hispanic, and older women; • there has been an increase in the racial and ethnic diversity of U.S. births, as well as a rise in the proportion of older and un-

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 DESCRIPTIVE EPIDEMIOLOGY AND TRENDS married mothers and a decrease in the proportion of teenaged mothers; and • low ( 40 pound) GWG has become more common. 2. American women of childbearing age are far from meeting national goals for dietary intake and physical activity, yet there is a dearth of nationally representative data on dietary intake, dieting practices and food insecurity among women of childbearing age in general and among pregnant women in particular. 3. About half of reproductive-aged American women are trying to lose weight, and another one-third of pregnant women may be attempting to maintain their weight. The prevalence of attempted weight loss during pregnancy doubled in the past 20 years. 4. Rates of preterm birth, GDM, and hypertensive disorders of preg- nancy are increasing. The rise in cesarean births and the decline in LGA births appear to result from medical practice patterns and social factors. 5. In the past 10 years, improvements that were observed during the twentieth century in maternal mortality and poor infant outcomes (mortality and low birth weight) have declined or ceased. 6. There are racial and ethnic disparities in nearly all weight-related predictors and outcomes reviewed. 7. Currently available data sources are inadequate for studying na- tional trends in GWG. Even after the IOM (1990) report called for more sophisticated analyses, major gaps in GWG surveillance remain; specifically, data on prepregnancy weight and height, reli- ance on self-reported weight gain, and nationally representative sources are lacking. 8. Gestational weight gain in excess of the recommended range for BMI is associated with significant postpartum weight retention. 9. Major gaps in surveillance of postpartum weight exist. Notably, most national studies lack data on postpartum weight and/or the variables needed for its proper interpretation (namely, prepreg- nancy height and weight, GWG, dietary intake, physical activity, and breastfeeding status). Action Recommendations Action Recommendation 2-1: The committee recommends that the Depart- ment of Health and Human Services conduct routine surveillance of GWG and postpartum weight retention on a nationally representative sample of women and report the results by prepregnancy BMI (includ-

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 WEIGHT GAIN DURING PREGNANCY ing all classes of obesity), age, racial/ethnic group, and socioeconomic status. Action Recommendation 2-2: The committee recommends that all states adopt the revised version of the birth certificate, which includes fields for maternal prepregnancy weight, height, weight at delivery, and ges- tational age at the last measured weight. In addition, all states should strive for 100 percent completion of these fields on birth certificates and collaborate to share data, thereby allowing a complete national picture as well as regional snapshots. Supporting Actions 1. At the first prenatal visit, health care providers should record weight at last menstrual period and maternal height without shoes. Gestational weight gain should be based on measured weights (in light clothing and no shoes) abstracted from prenatal records. Gestational age at the last recorded weight should be documented, preferably through an early ultrasound, to properly evaluate ad- equacy of weight gain. To aid in data analysis, all data should be collected in a continuous form rather than categorically. 2. As part of maternal weight surveillance, health care providers should document the prevalence of obesity grades I, II, and II rather than categorize women into one obesity group (BMI > 30 kg/m2). Areas for Additional Investigation The committee identified the following areas for further investigation to support its research recommendations: • The research community should conduct future monitoring of GWG. • Federal agencies should standardize the use of the WHO BMI cut- off points in all data collection relevant to monitoring weight gain in pregnancy. REFERENCES American Psychiatric Association. 1994. Diagnostic and Statistical Manual of Mental Disor- ders. Washington, DC: American Psychiatric Association. Bish C. L., H. M. Blanck, M. K. Serdula, M. Marcus, H. W. Kohl, 3rd and L. K. Khan. 2005. Diet and physical activity behaviors among Americans trying to lose weight: 2000 Behav- ioral Risk Factor Surveillance System. Obesity Research 13(3): 596-607.

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 DESCRIPTIVE EPIDEMIOLOGY AND TRENDS Bish C. L., S. Y. Chu, C. K. Shapiro-Mendoza, A. J. Sharma and H. M. Blanck. 2009. Trying to lose or maintain weight during pregnancy-United States, 2003. Matern Child Health Journal 13(2): 286-292. CDC (Centers for Disease Control and Prevention). 2004. Smoking during pregnancy—United States, 1990-2002. Morbidity and Mortality Weekly Report 53(39): 911-915. CDC. 2005. Trends in leisure-time physical inactivity by age, sex, and race/ethnicity—United States, 1994-2004. Morbidity and Mortality Weekly Report 54(39): 991-994. CDC. 2007. Prevalence of regular physical activity among adults—United States, 2001 and 2005. Morbidity and Mortality Weekly Report 56(46): 1209-1212. CDC. 2008a. Morbidity and Mortality Weekly Report 57(5): 127. CDC. 2008b. Morbidity and Mortality Weekly Report 57(11): 281-308. Chu S. Y., S. Y. Kim, C. H. Schmid, P. M. Dietz, W. M. Callaghan, J. Lau and K. M. Curtis. 2007. Maternal obesity and risk of cesarean delivery: a meta-analysis. Obesity Reiews 8(5): 385-394. Cogswell M. E., M. K. Serdula, A. H. Mokdad and D. F. Williamson. 1996. Attempted weight loss during pregnancy. International Journal of Obesity and Related Metabolic Disorders 20(4): 373-375. Compton W. M., K. P. Conway, F. S. Stinson and B. F. Grant. 2006. Changes in the prevalence of major depression and comorbid substance use disorders in the United States between 1991-1992 and 2001-2002. American Journal of Psychiatry 163(12): 2141-2147. Evenson K. R., D. A. Savitz and S. L. Huston. 2004. Leisure-time physical activity among pregnant women in the US. Paediatric and Perinatal Epidemiology 18(6): 400-407. Flegal K. M., M. D. Carroll, R. J. Kuczmarski and C. L. Johnson. 1998. Overweight and obesity in the United States: prevalence and trends, 1960-1994. International Journal of Obesity and Related Metabolic Disorders 22(1): 39-47. Gaynes B. N., N. Gavin, S. Meltzer-Brody, K. N. Lohr, T. Swinson, G. Gartlehner, S. Brody and W. C. Miller. 2005. Perinatal depression: prevalence, screening accuracy, and screening outcomes. Eidence Report/Technology Assessessment (Summary) (119): 1-8. Getahun D., C. Nath, C. V. Ananth, M. R. Chavez and J. C. Smulian. 2008. Gestational diabetes in the United States: temporal trends 1989 through 2004. American Journal of Obstetrics and Gynecology 198(5): 525 e521-e525. Guenther P. M., K. W. Dodd, J. Reedy and S. M. Krebs-Smith. 2006. Most Americans eat much less than recommended amounts of fruits and vegetables. Journal of the American Dietetic Association 106(9): 1371-1379. HHS (U.S. Department of Health and Human Services). 2000. Healthy People 00: Un- derstanding and Improing Health, nd Ed. Washington, DC: Government Printing Office. HHS. 2008. Physical Actiity Guidelines Adisory Committee Report. Washington, DC: U.S. Government Printing Office. Hoyert D. L. 2007. Maternal mortality and related concepts. Vital and Health Statistics. Series : Analytical Studies (33): 1-13. IOM (Institute of Medicine). 1990. Nutrition During Pregnancy. Washington, DC: National Academy Press. IOM. 2005. Preenting Childhood Obesity: Health in the Balance. Washington, DC: The National Academies Press. Jaquet D., S. Swaminathan, G. R. Alexander, P. Czernichow, D. Collin, H. M. Salihu, R. S. Kirby and C. Levy-Marchal. 2005. Significant paternal contribution to the risk of small for gestational age. British Journal of Obstetrics and Gynaecology 112(2): 153-159. Kim S. Y., P. M. Dietz, L. England, B. Morrow and W. M. Callaghan. 2007. Trends in pre- pregnancy obesity in nine states, 1993-2003. Obesity (Siler Spring) 15(4): 986-993.

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 WEIGHT GAIN DURING PREGNANCY MacDorman M. F., F. Menacker and E. Declercq. 2008. Cesarean birth in the United States: epidemiology, trends, and outcomes. Clinics in Perinatology 35(2): 293-307. Martin J. A., H. C. Kung, T. J. Mathews, D. L. Hoyert, D. M. Strobino, B. Guyer and S. R. Sutton. 2008. Annual summary of vital statistics: 2006. Pediatrics 121(4): 788-801. Mathews T. J. and M. F. MacDorman. 2007. Infant mortality statistics from the 2004 period linked birth/infant death data set. National Vital Statistics Reports 55(14): 1-32. Menacker F., E. Declercq and M. F. Macdorman. 2006. Cesarean delivery: background, trends, and epidemiology. Seminars in Perinatology 30(5): 235-241. Mokdad A. H., M. K. Serdula, W. H. Dietz, B. A. Bowman, J. S. Marks and J. P. Koplan. 1999. The spread of the obesity epidemic in the United States, 1991-1998. Journal of the American Medical Association 282(16): 1519-1522. NCHS (National Center for Health Statistics). 2002. Births: final data for 2001. National Vital Statistics Reports 51(2): 1-102. NCHS. 2005. Births: preliminary data for 2004. National Vital Statistics Reports 54(8): 1-17. NCHS. 2007a. Births: final data for 2005. National Vital Statistics Reports 56(6): 1-103. NCHS. 2007b. Health, United States, 00. Hyattsville, MD: Public Health Service. NHLBI (National Heart, Lung, and Blood Institute). 1998. Clinical Guidelines on the Identifi- cation, Ealuation, and Treatment of Oerweight and Obesity in Adults. National Insti- tutes of Health Publication 98-4083. Washington, DC: National Institutes of Health. Nielsen S. J. and B. M. Popkin. 2004. Changes in beverage intake between 1977 and 2001. American Journal of Preentie Medicine 27(3): 205-210. Nielsen S. J., A. M. Siega-Riz and B. M. Popkin. 2002. Trends in energy intake in U.S. be- tween 1977 and 1996: similar shifts seen across age groups. Obesity Research 10(5): 370-378. Ogden C. L., M. D. Carroll, L. R. Curtin, M. A. McDowell, C. J. Tabak and K. M. Flegal. 2006. Prevalence of overweight and obesity in the United States, 1999-2004. Journal of the American Medical Association 295(13): 1549-1555. Ogden C. L., M. D. Carroll and K. M. Flegal. 2008. High body mass index for age among US children and adolescents, 2003-2006. Journal of the American Medical Association 299(20): 2401-2405. Petersen A. M., T. L. Leet and R. C. Brownson. 2005. Correlates of physical activity among pregnant women in the United States. Medicine and Science in Sports and Exercise 37(10): 1748-1753. Ryan A. S., Z. Wenjun and A. Acosta. 2002. Breastfeeding continues to increase into the new millennium. Pediatrics 110(6): 1103-1109. Serdula M. K., D. F. Williamson, R. F. Anda, A. Levy, A. Heaton and T. Byers. 1994. Weight control practices in adults: results of a multistate telephone survey. American Journal of Public Health 84(11): 1821-1824. Serdula M. K., A. H. Mokdad, D. F. Williamson, D. A. Galuska, J. M. Mendlein and G. W. Heath. 1999. Prevalence of attempting weight loss and strategies for controlling weight. Journal of the American Medical Association 282(14): 1353-1358. Svensson A. C., Y. Pawitan, S. Cnattingius, M. Reilly and P. Lichtenstein. 2006. Familial aggregation of small-for-gestational-age births: the importance of fetal genetic effects. American Journal of Obstetrics and Gynecology 194(2): 475-479. Thompson D., Graham C., Burch D., Watson A. and Phelps A. 2005. Pregnancy Related Mortality Associated with Obesity in Florida  through 00. Tallahassee, FL: Florida Department of Health, Division of Family Health Services, Bureau of Family and Community Health.

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 DESCRIPTIVE EPIDEMIOLOGY AND TRENDS Wallis A. B., A. F. Saftlas, J. Hsia and H. K. Atrash. 2008. Secular trends in the rates of pre- eclampsia, eclampsia, and gestational hypertension, United States, 1987-2004. American Journal of Hypertension 21(5): 521-526. WHO (World Health Organization). 1998. Obesity—preenting and managing the global epidemic. WHO Consultation on Obesity Report. Geneva. Websites: http://www.cdc.gov/prams/ http://www.cdc.gov/PEDNSS/pnss_tables/pdf/national_table20.pdf http://www.cdc.gov/ifps/questionnaires.htm http://www.cdc.gov/nchs/vitalstats.htm http://www.cdc.gov/brfss/index.htm http://www.ers.usda.gov/Publications/ERR49/ERR49.pdf http://mchb.hrsa.gov/whusa08/hstat/mh/pages/237mm.html http://www.cdc.gov/nchs/data/databriefs/db09.htm http://www.marchofdimes.com/files/MP_Late_Preterm_Birth-Every_Week_Matters_3-24- 06.pdf http://www.cdc.gov/nccdphp/dnpa/obesity/childhood/prevalence.htm

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