The epidemiology of non-fatal injuries among 11-, 13- and 15-year old youth in 11 countries: findings from the 1998 WHO-HBSC cross national survey.

The primary objective was to present a cross-country comparison of injury rates, contexts and consequences. The research design was the analysis of data from the 1998 cross-national Health Behaviour in School-aged Children survey and 52955 schoolchildren from 11 countries, aged 11, 13 and 15 years, completed a self-administrated questionnaire. A total of 41.3% of all children were injured and needed medical treatment in the past 12 months. Injury rates among boys were higher than among girls, 13.3% reported activity loss due to injury and 6.9% reported severe injury consequences. Most injuries occurred at home and at a sport facility, mainly during sport activity. Fighting accounted for 4.1% of injuries. This paper presents the first cross-national comparison of injury rates and patterns by external cause and context. Findings present cross-country similarities in injury distribution by setting and activity. These findings emphasize the importance of the development of global prevention programmes designed to address injuries among youth.

Factors associated with bicycle helmet use among young adolescents in a multinational sample.

OBJECTIVE: To determine factors associated with variation in bicycle helmet use by youth of different industrialized countries. DESIGN: A multinational cross sectional nationally representative survey of health behaviors including symptoms, risk taking, school setting, and family context. SETTING: School based survey of 26 countries. SUBJECTS: School students, ages 11, 13, and 15 years totaling 112,843. OUTCOME MEASURES: Reported frequency of bicycle helmet use among bicycle riders. RESULTS: Reported helmet use varied greatly by country from 39.2% to 1.9%, with 12 countries reporting less than 10% of the bicycle riders as frequent helmet users and 14 countries more than 10%. Reported helmet use was highest at 11 years and decreased as children's age increased. Use was positively associated with other healthy behaviors, with parental involvement, and with per capita gross domestic product of the country. It is negatively associated with risk taking behaviors. Countries reported to have interventions promoting helmet use, exemplified by helmet giveaway programmes, had greater frequency of reported helmet use than those without programmes. CONCLUSIONS: Bicycle helmet use among young adolescents varies greatly between countries; however, helmet use does not reach 50% in any country. Age is the most significant individual factor associated with helmet for helmet using countries. The observation that some helmet promotion programmes are reported for countries with relatively higher student helmet use and no programmes reported for the lowest helmet use countries, suggests the possibility of a relation and the need for objective evaluation of programme effectiveness.

Where children drown, United States, 1995.

CONTEXT: Drowning is the second leading cause of unintentional injury death among children ages 1 to 19 years. Details about the specific site of submersion are important for implementation of primary prevention efforts, but are not routinely available from national data. OBJECTIVES: To provide national data about the specific sites of drowning among US children and to examine site-specific drowning rates by age, race, and gender. SETTING: United States, 1995. DESIGN: Information was abstracted from death certificates for unintentional drownings among children <20 years of age. The site of drowning was coded from free text on death certificates. Proportional distributions of the site of drowning by age, region, gender, and race were examined. Site-specific drowning rates were calculated by age, race, and gender. Denominators were based on US Census Bureau, June 1995 estimates of the US population. RESULTS: For 1995, death certificates were obtained for 1420 unintentional drownings among children <20 years of age, 98% of the number of drowning deaths reported by the National Center for Health Statistics for the same year. Site of drowning was specified on 1308 (92%) death certificates. Fifty-five percent of infant drownings were in bathtubs. Among children between the ages of 1 to 4 years, 56% of drownings were in artificial pools and 26% were in other bodies of freshwater. Among older children, 63% of drownings were in natural bodies of freshwater. Site-specific drowning rates varied by race. Importantly, after the age of 5 years, the risk of drowning in a swimming pool was greater among black males compared with white males with rate ratios of 15.1 (95% confidence interval: 6.7-38.5) among 10- to 14-year-olds and 12.8 (95% confidence interval: 6.5-26.9) among 15- to 19-year-olds. CONCLUSION: The variety of sites in which children drown, even within specific age groups, emphasizes the need for a multifaceted approach to prevention. Reductions in the relatively high rates of drowning among black adolescent males will require targeted interventions to prevent swimming pool drownings among this group.

Bullying behaviors among US youth: prevalence and association with psychosocial adjustment.

CONTEXT: Although violence among US youth is a current major concern, bullying is infrequently addressed and no national data on the prevalence of bullying are available. OBJECTIVES: To measure the prevalence of bullying behaviors among US youth and to determine the association of bullying and being bullied with indicators of psychosocial adjustment, including problem behavior, school adjustment, social/emotional adjustment, and parenting. DESIGN, SETTING, AND PARTICIPANTS: Analysis of data from a representative sample of 15 686 students in grades 6 through 10 in public and private schools throughout the United States who completed the World Health Organization's Health Behaviour in School-aged Children survey during the spring of 1998. MAIN OUTCOME MEASURE: Self-report of involvement in bullying and being bullied by others. RESULTS: A total of 29.9% of the sample reported moderate or frequent involvement in bullying, as a bully (13.0%), one who was bullied (10.6%), or both (6.3%). Males were more likely than females to be both perpetrators and targets of bullying. The frequency of bullying was higher among 6th- through 8th-grade students than among 9th- and 10th-grade students. Perpetrating and experiencing bullying were associated with poorer psychosocial adjustment (P<.001); however, different patterns of association occurred among bullies, those bullied, and those who both bullied others and were bullied themselves. CONCLUSIONS: The prevalence of bullying among US youth is substantial. Given the concurrent behavioral and emotional difficulties associated with bullying, as well as the potential long-term negative outcomes for these youth, the issue of bullying merits serious attention, both for future research and preventive intervention.

Association between infant breastfeeding and overweight in young children.

CONTEXT: It has been suggested that breastfeeding is protective against children becoming overweight, and that there is a dose-dependent effect of its duration. OBJECTIVE: To determine whether breastfeeding and its duration are associated with a reduced risk of being overweight among young children in the United States. DESIGN AND SETTING: Data on infant feeding and child overweight status were taken from the third National Health and Nutrition Examination Survey (NHANES III), a cross-sectional health examination survey conducted from 1988-1994. SUBJECTS: Sample of 2685 US-born children between the ages of 3 and 5 years, with birth certificates, height and weight measures, and information on infant feeding. MAIN OUTCOME MEASURES: A body mass index (BMI) between the 85th and 94th percentile was considered at risk of overweight and a BMI in the 95th percentile or higher was considered being overweight. RESULTS: After adjusting for potential confounders, there was a reduced risk of being at risk of overweight for ever breastfed children (adjusted odds ratio [AOR], 0.63; 95% confidence interval [CI], 0.41-0.96) compared with those never breastfed. There was no reduced risk of being overweight (AOR, 0.84; 95% CI, 0.62-1.13). There was no clear dose-dependent effect of the duration of full breastfeeding on being at risk of overweight or overweight and no threshold effect. The strongest predictor of child overweight status was the mother's concurrent weight. The rate of children being overweight nearly tripled with maternal overweight status (BMI, 25.0-29.9 kg/m(2); AOR, 2.95; 95% CI, 1.35-6.42) and more than quadrupled with maternal obesity status (BMI >/=30.0 kg/m(2); AOR, 4.34; 95% CI, 2.50-7.54). CONCLUSIONS: There are inconsistent associations among breastfeeding, its duration, and the risk of being overweight in young children. Breastfeeding continues to be strongly recommended, but may not be as effective as moderating familial factors, such as dietary habits and physical activity, in preventing children from becoming overweight.

Emergency visits for sports-related injuries.

STUDY OBJECTIVE: We sought to estimate the effect and magnitude of patients with sports-related injuries presenting to hospital emergency departments in the United States and to examine differences in patient and visit characteristics between sports- and nonsports-related injuries. METHODS: Data from the 1997 and 1998 National Hospital Ambulatory Medical Care Survey, a national probabilistic sample of 496 US hospital EDs, were combined to examine emergency visits for sports-related injuries. Data from 16,997 sample ED encounter records for injuries that included narrative cause of injury text were analyzed. Narrative text entries were coded to 1 of 84 sport and recreational activity codes. Sample weights were applied to provide annual national estimates. Estimates of sports-related injury visits were based on 1,775 records with an assigned sports-related activity code. RESULTS: There were an average annual estimated 2.6 million emergency visits for sports-related injuries by persons between the ages of 5 and 24 years. They accounted for over 68% of the total 3.7 million sport injuries presented to the ED by persons of all ages. As a proportion of all kinds of injuries presenting to the ED, sports-related injuries accounted for more than one fifth of the visits by persons 5 to 24 years old. The use rate was 33.9 ED visits per 1,000 persons in this age group (95% confidence interval 30.3 to 37.5). The sports-related injury visit rate for male patients was more than double the rate for female patients (48.2 versus 19.2 per 1,000 persons between 5 and 24 years of age). Visits from sports-related activities for this age group were more frequent for basketball and cycling compared with other categories (eg, baseball, skateboarding, gymnastics). Compared with nonsports-related injuries for this age group, sports-related injuries were more likely to be to the brain or skull and upper and lower extremities. Patients with sports-related injuries were more likely to have a diagnosis of fracture and sprain or strain and less likely to have an open wound. They were also more likely to have diagnostic and therapeutic services provided, especially orthopedic care. CONCLUSION: Sports-related activities by school-age children and young adults produce a significant amount of emergency medical use in the United States. The ED is an appropriate venue to target injury prevention counseling.

Stature, weight, and body mass among young US children born at term with appropriate birth weights.

OBJECTIVE: To describe weight, stature, and body mass index (BMI) changes occurring before the age of 7 years, which may influence the prevalence of overweight in adolescence and adulthood. METHODS: Regression models predicting height and weight at ages 2 months to 6. 75 years were based on the third National Health and Nutrition Examination Survey. Birth certificate data were used to adjust ethnic-specific models for birth weight for gestational age. RESULTS: Attained height is higher for non-Hispanic black children than for either non-Hispanic white or Mexican American children (P 85th percentile than either non-Hispanic white or black children (boys = 25.6%, SE = 2.7 compared with 14.1%, SE = 1.7 and 16.5%, SE = 1.7, respectively; girls = 21.9%, SE = 3.6 compared with 13.0%, SE = 1.7 and 13.7%, SE = 2.2, respectively). For non-Hispanic whites and Mexican Americans and for non-Hispanic black boys, BMI decreased slightly between ages 2 and 6.75 years; BMI for non-Hispanic black girls did not. CONCLUSION: Size differences before the age of 7 years may influence later ethnic-specific overweight prevalence, independent of prenatal influences.

Use of high-technology care among women with high-risk pregnancies in the United States.

OBJECTIVE: Infant mortality has been reduced dramatically with the development of perinatal regionalized high-technology care. Our objective was to assess use of high technology care among women with high-risk pregnancies in the urban and rural United States. METHODS: The 1988 National Maternal and Infant Health Survey was linked to the 1988 American Hospital Association survey of all obstetrical hospitals. Hospitals were classified into five levels of care based on services and staffing. Women were classified as having high-risk pregnancies using two definitions: (1) gestational age < 34 weeks and birthweight < 1500 g (High Risk I) and (2) the first definition or an antenatal high-risk medical diagnoses (High Risk II). Analyses assessed the proportion of high-risk women delivering in appropriate locations in the rural and urban United States and explored how personal characteristics, insurance status, and use and source of prenatal care influenced where high-risk women delivered. RESULTS: 71.2% of High Risk I and 55.9% of High Risk II women delivered in a high-technology facility (Level IIA or III). Fifty percent of HRI rural women delivered in tertiary high-technology hospitals and 39% of HRII rural women delivered in a high-technology hospital. High-risk urban women were two to three times more likely to deliver in a high-technology facility compared to their rural counterparts. The multivariate analysis showed that Black high-risk women were more likely to deliver in a high-technology setting and that receipt of prenatal care in a private setting lowered the odds of delivering in a high-technology setting when other factors were controlled. CONCLUSIONS: In an era where regionalized perinatal care was not threatened by managed care, a large proportion of high-risk women received care in less than optimal settings. Rural high-risk women delivered in high-technology hospitals less often than their urban counterparts. The multivariate analyses implied that the potential barriers to care may be more important among those considered more socially advantaged, who may be more at the mercy of managed care. The current reimbursement environment, which discourages referral to specialists and high-technology care, could result in less access today.

Early infant feeding and growth status of US-born infants and children aged 4-71 mo: analyses from the third National Health and Nutrition Examination Survey, 1988-1994.

BACKGROUND: There is controversy over what growth references to use in evaluating breast-fed infants and concern about whether never-breast-fed infants are at risk of overweight in childhood. OBJECTIVE: The objective of this study was to determine whether infants who are exclusively breast-fed for 4 mo differ in average size from infants who are fed in other ways and whether such differences persist through age 5 y. DESIGN: Data from the third National Health and Nutrition Examination Survey (NHANES III) were linked to birth certificates of US-born infants and children. Feeding groups were defined on the basis of feeding patterns over the first 4 mo of life: exclusively breast-fed for 4 mo, partially breast-fed, breast-fed for <4 mo, and never breast-fed. Growth status, indexed as internally derived z scores (SD units) for weight, length (height), weight-for-length (height), midupper arm circumference, and triceps skinfold thickness, was compared among feeding groups. RESULTS: The final sample consisted of 5594 non-Hispanic white, non-Hispanic black, and Mexican American infants and children aged 4-71 mo. Of these, 21% were exclusively breast-fed for 4 mo, 10% were partially breast-fed, 24% were breast-fed for <4 mo, and 45% were never breast-fed. At 8-11 mo, infants who were exclusively breast-fed for4 mo had adjusted mean z scores for weight (-0.21; -0.2 kg), weight-for-length (-0.27), and midupper arm circumference (-0.15) that differed significantly from zero (P < 0. 05). By 12-23 mo, the differences had dissipated; there were no significant differences subsequent to 5 y. Triceps skinfold thickness was not related to early infant feeding. CONCLUSION: Infants who were exclusively breast-fed for 4 mo weighed less at 8-11 mo than did infants who were fed in other ways, but there were few other significant differences in growth status through age 5 y associated with early infant feeding.

Child and adolescent injury research in 1998: a summary of abstracts submitted to the Ambulatory Pediatrics Association and the American Public Health Association.

OBJECTIVE: To describe current research in child and adolescent injury prevention by pediatric and public health investigators for comparison with national recommendations and agendas. DATA SOURCES: Abstracts submitted to the 1998 annual meetings of the Pediatric Academic Societies/Ambulatory Pediatrics Association and the American Public Health Association on injury or violence in children or adolescents. STUDY SELECTION: All abstracts of projects that addressed primarily injury or violence prevention involving children or adolescents. DATA EXTRACTION: For 123 abstracts, 2 coauthors extracted and classified age of the population, type of injury, study design, sizes of the sample and denominator, and type of outcome. RESULTS: Adolescents were the most frequent (49%) age group included. The investigations were concerned most with injuries caused by violence (33%), followed by motor vehicle trauma (14%) and burns (7%). Descriptive surveillance (38%), surveys (32%), and case series (13%) comprised the overwhelming majority of methods used. The studies primarily sought to identify risk factors for injury (32%), describe the victims (20%), or measure knowledge and/or practice (26%). Nine studies (7%) sought to measure the effect of interventions in some way, and only 2 focused primarily on methodology development. CONCLUSIONS: Injury prevention research projects presented at the 1998 Pediatric Academic Societies and American Public Health Association meetings were proportionate to the frequencies of injury by age and by external cause in the United States. However, in comparison with recommendations for agendas of national injury prevention research, more research is needed to improve injury prevention methods and to evaluate interventions.

Factors associated with tympanostomy tube insertion among preschool-aged children in the United States.

OBJECTIVES: Recurrent and persistent otitis media is often treated by tympanostomy tube insertion to ventilate the middle ear and restore hearing. This study examined the factors that predict which children are most likely to receive tympanostomy tubes through 3 years of age. METHODS: Multiple logistic regression was conducted on data from a nationally representative sample of children (N = 8285). RESULTS: By 3 years of age, 6.8% of US children had tubes inserted. Logistic regression indicated that after control for number of ear infections, children without any gaps in health insurance, who attended a day-care center, who were White, whose birth-weight was less than 1500 g, and who lived in the Midwest or South were significantly more likely to have tympanostomy tubes. CONCLUSIONS: These data suggest that differences exist as to who receives tubes. Of particular concern are differences by race/ethnicity and continuity of health insurance coverage. With expansions in health care coverage to larger proportions of uninsured children, it will be important to monitor these programs to ensure that all children who may need tympanostomy tubes have access to them.

Frequent ear infections in association with child-care characteristics, based on the 1988 Child Health Supplement to the National Health Interview Survey.

Using the 1988 Child Health Supplement to the National Health Interview Survey, we analysed the association between child-care characteristics and frequent ear infections among children under 6 years attending child care. We observed strong associations for 1- to 2-year-old children for variables involving exposure to many different children, including number of children in the main setting and one or more changes in child-care arrangement in the past year. No significant effects were observed for the children under 1 year, but sample sizes were small. Likewise, no strong associations were observed for the 3- to 5-year-old children, but they may have outgrown the detrimental effects of repeated respiratory tract infections.

Growth and fatness at three to six years of age of children born small- or large-for-gestational age.

OBJECTIVE: To compare young children 3 to 6 years of age who were born small-for-gestational age (SGA; <10th percentile for gestational age) or large-for-gestational age (LGA; >/=90th percentile) with those who were born appropriate-for-gestational age (10th-89th percentile) to determine whether there are differences in growth and fatness in early childhood associated with birth weight status. DESIGN AND METHODS: National sample of 3192 US-born non-Hispanic white, non-Hispanic black, and Mexican-American children 3 to 6 years of age (36-83 months) examined in the third National Health and Nutrition Examination Survey and for whom birth certificates were obtained. On the birth certificates, length of gestation from the mother's last menstrual period was examined for completeness, validity, and whether the pattern of missing (n = 141) and invalid data (n = 147) on gestation was random. Gestation was considered invalid when >44 weeks, or when at gestations of

Birth weight for gestational age of Mexican American infants born in the United States.

OBJECTIVE: To develop a reference for birth weight for gestational age to identify Mexican American infants born in the United States who are small or large for gestational age. METHODS: Reference percentiles were developed for Mexican American and non-Hispanic white births, using national vital statistics from 1992-1994 for Mexican Americans (n = 1,197,916) and 1994 for non-Hispanic whites (n = 2,238,457). Birth weights and gestation from the last menstrual period were taken from birth certificates. Smoothed curves were fit, using unweighted fourth-degree polynomial equations, for the tenth, 50th, and 90th percentiles by gender and parity. RESULTS: Mexican American infants were heavier than non-Hispanic white infants between 30 and 37 weeks' gestation for all parities and both genders. However, at term there was consistent crossover. Non-Hispanic white infants were heavier at or after 37 through 42 weeks' gestation, whereas the growth of Mexican American infants appeared to slow. Beginning at 37 weeks, the differences in weights of infants of primiparas increased to more than 100 g by 40 weeks; the differences were only slightly less for infants of multiparas. CONCLUSION: Given differences in distribution of birth weights for gestational age between Mexican Americans and non-Hispanic whites, the ability to recognize fetal growth restriction (FGR) or excessive growth is questionable. These data provide a reference for Mexican Americans for clinical use and for future studies in identifying infants at risk for FGR or overgrowth.

Deaths attributable to injuries in infants, United States, 1983-1991.

OBJECTIVE: To describe risk factors for injury death among infants in the United States by the specific external cause of death. METHODS: Data were analyzed from the US-linked birth/infant death files for the years 1983-1991. Potential risk factors for injury death were identified from birth certificate data and included both maternal and infant factors. Injury rates were calculated by external cause of death. Characteristics of infants who died from an injury were compared with those of the entire birth cohort. The independent effect of potential risk factors was assessed in multivariate analyses using a case-control study design. RESULTS: A total of 10 370 injury deaths were identified over the 9-year study period (29. 72/100 000 live births). The leading causes of death were homicide, suffocation, motor vehicle crashes, and choking (inhalation of food or objects). There was no significant temporal trend in the overall rate of injury death; however, this was because significant increases in the rates of death from homicide (6.4%/year) and mechanical suffocation (3.7%/year) were offset by decreases in rates of death from fires (-4.7%/year) and choking (-4.6%/year). In adjusted analyses, infants born to mothers with no prenatal care, <12 years of education, two or more previous live births, Native American race, or <20 years of age were at twice the risk of injury death compared with the lowest risk groups (initiation of prenatal care in the first trimester, >/=16 years of education, no previous live births, white, or >/=25 years of age). When analyzed by the specific cause of death, the factors that were associated most strongly with death varied. For example, Native Americans were at greatest risk of a motor vehicle related death (compared with whites: OR: 3.6; 95% CI: 1.8-7.1), and infants with birth weights of <1500 g were at greatest risk of death attributable to inhalation of food (compared with >/=2500 g: OR: 9.6; 95% CI: 3.3-28.0) or objects (OR: 11.8; 95% CI: 4.5-30.5). CONCLUSION: A number of sociodemographic characteristics are associated with an increased risk of injury-related death in infants. The strength of associations between specific risk factors and death varies with the external cause of death, thus identifying high-risk subgroups for targeting of cause-specific interventions and simultaneously increasing our understanding of the individual and societal mechanisms underlying these tragedies.

Infant injury deaths with unknown intent: what else do we know?

OBJECTIVES: Strong evidence based on case record reviews indicates that the incidence of child homicide reported from death certificates is under ascertained. The characteristics of infant injury fatalities with undetermined, but suspicious, intent were compared for the probability that they should be considered homicides. METHODS: Using linked birth and death certificates for all birth cohorts in the US from 1983-91, 2345 injury fatalities reported as intentional, 7594 as unintentional, and 431 as undetermined intent were identified. Maternal and infant variables potentially predictive of injury fatalities were selected based on increased bivariate associations. Relative risks of injury death by intentional, unintentional, and undetermined intent were assessed for maternal and infant characteristics. RESULTS: Relative risks were consistently higher across all intent categories for infants of mothers with the least education, no prenatal care, young maternal age, and single marital status, as well as for infants who are second or later born, preterm, black, or American Indian. Fatalities with undetermined intent have larger relative risks in the highest risk categories than either intentional or unintentional injuries. Deaths with undetermined intent have risk profiles that more closely resemble profiles for intentional deaths than unintentional. CONCLUSIONS: Injury homicide rates would be almost 20% greater than official classifications indicate if deaths with undetermined intent were included. In analyses of infant homicide, excluding deaths of undetermined intent may lead to an underestimation of the magnitude of the public health problem of intentional injuries among infants. Other studies based on record reviews from multiple sources indicate that misclassification and under ascertainment of homicides may be even greater.

Racial differences in the patterns of singleton preterm delivery in the 1988 National Maternal and Infant Health Survey.

OBJECTIVES: To determine if the association between race and preterm delivery would persist when preterm delivery was partitioned into two etiologic pathways. METHODS: We evaluated perinatal and obstetrical data from the 1988 National Maternal and Infant Health Survey and classified preterm delivery as spontaneous or medically indicated. Discrete proportional hazard models were fit to assess the risk of preterm delivery for Black women compared with White women adjusting for potential demographic and behavioral confounding variables. RESULTS: Preterm delivery occurred among 17.4% of Black births and 6.7% of White births with a Black versus White unadjusted hazard ratio (HR) of 2.8 (95% CI = 2.4-3.3). The adjusted HR for a medically indicated preterm delivery showed no racial difference in risk (HR = 1.0, 95% CI = 0.4-2.6). However, for spontaneous preterm delivery between 20 and 28 weeks gestation, the Black versus White adjusted hazard ratio (HR) was 4.9 (95% CI = 3.4-7.1). CONCLUSIONS: Although we found an increased unadjusted HR for preterm delivery among Black women compared with White women, the nearly fivefold increase in adjusted HR for the extremely preterm births and the absence of a difference for medically indicated preterm delivery was unexpected. Given the differences in the risks of preterm birth between Black and White women, we recommend to continue examining risk factors for preterm delivery after separating spontaneous from medically indicated preterm birth and subdividing preterm delivery by gestational age to shed light on the reasons for the racial disparity.

Growth of infants and young children born small or large for gestational age: findings from the Third National Health and Nutrition Examination Survey.

OBJECTIVES: To compare the growth profiles of infants and young children born small for gestational age (SGA, < 10th percentile birth weight for gestation) or large for gestational age (LGA, > or =90th percentile) with those appropriate for gestational age, and to document the expected growth patterns through early childhood based on national health examination survey data. SAMPLE: Infants and children, 2 to 47 months of age, who were born in the United States and examined using the Third National Health and Nutrition Examination Survey (1988-1994). MAIN OUTCOME MEASURES: Measurements of growth status based on normalized distributions (z scores or standard deviation units [SDUs] for weight, length, and head circumference. RESULTS: Prevalence rates were as follows: SGA infants, 8.6%; appropriate for gestational age infants, 80.9%; and LGA infants, 10.5%. Infants who were SGA appeared to catch up in weight in the first 6 months, but thereafter maintained a deficit of about -0.75 SDUs compared with infants who were appropriate for gestational age. The weight status of LGA infants remained at about +0.50 SDUs through 47 months of age. Length and head circumference were also associated with birth weight status, averaging over -0.60 SDUs for SGA infants and +0.43 SDUs for LGA infants. CONCLUSIONS: Birth weight status is related to growth rates in infancy and early childhood, which underscores the importance of considering child growth relative to birth status when using growth charts. Small for gestational age infants remain shorter and lighter and have smaller head circumferences, while LGA infants grow longer and heavier and have larger head circumferences.

Muscularity and fatness of infants and young children born small- or large-for-gestational-age.

OBJECTIVE: There is growing interest in the extent to which body composition, both short- and long-term, differs in infants and children born at the extremes of birth weight. This is because a growing number of studies have linked low birth weight and fetal growth restriction to the chronic diseases in adulthood that often are obesity-related, and there is also evidence to suggest that heavy infants may be at increased risk for obesity in later life, again with the attendant obesity-related chronic diseases. Our objective was to compare anthropometric indices of body composition of infants and young children born small-for-gestational-age (SGA, <10th percentile) or large-for-gestational age (LGA, >/=90th percentile) with those of normal birth weight status (appropriate-for-gestational-age, AGA) in a US sample. DESIGN: National sample of US-born non-Hispanic white, non-Hispanic black, and Mexican-American infants and young children, 2 to 47 months of age, examined in the third National Health and Nutrition Examination Survey (NHANES III, 1988-1994), for whom birth certificates were obtained. The primary outcomes were normalized anthropometric indices (z scores or standard deviation units [SDU]) of nutritional status and body composition (mid-upper arm circumference, triceps and subscapular skinfolds, mid-upper arm muscle and mid-upper arm fat areas (UFA), and the arm fat index). The outcomes thus were scaled to permit comparison across chronologic ages. RESULTS: The prevalence of SGA was 8.6%, appropriate-for-gestational-age 80.9%, and LGA 10.5%. From ages 2 to 47 months, for infants and young children born SGA, there was a persistent overall deficit in muscularity (mid-upper arm circumference and mid-upper arm muscle area) of approximately -0.50 SDU, but less of a deficit in fatness, particularly at the youngest ages. For infants and young children born LGA, there was a surfeit in muscularity of approximately 0.45 SDU, with less of a surfeit in fatness, particularly at the youngest ages. Across all ages, the mean UFA showed a statistically significant deficit for SGA children (-0.27 +/- 0.10 SDU) and surfeit for LGA children (0.24 +/- 0.08 SDU). At individual ages for UFA and at individual and all ages combined for skinfold thicknesses, there were no significant differences in level of subcutaneous fatness in the three birth-weight-for-gestational-age groups. There was a tendency in the first year for the arm fat index (% arm fat) to be significantly higher for SGA infants, but the effect did not persist after the first year. CONCLUSION: SGA infants remain smaller and LGA infants larger in size through early childhood, but the discrepancies in weight are primarily attributable to differences in lean body mass (muscularity). Fatness is less affected. Thus, based on the fatness indicators used, at any given weight for infants and children 2 to 47 months of age, percent body fat appears to be relatively higher for children who were SGA at birth and lower in those who were LGA at birth. These differences in body composition for SGA infants support the evidence documenting a link between disturbances in intrauterine growth and chronic disease associated with subsequent adiposity in adulthood.