Amy M. Branum

Food Allergy Among Children in the United States

OBJECTIVES: The goals were to estimate the prevalence of food allergy and to describe trends in food allergy prevalence and health care use among US children. METHODS: A cross-sectional survey of data on food allergy among children <18 years of age, as reported in the 1997–2007 National Health Interview Survey, 2005–2006 National Health and Nutrition Examination Survey, 1993–2006 National Hospital Ambulatory Medical Care Survey and National Ambulatory Medical Care Survey, and 1998–2006 National Hospital Discharge Survey, was performed. Reported food allergies, serum immunoglobulin E antibody levels for specific foods, ambulatory care visits, and hospitalizations were assessed. RESULTS: In 2007, 3.9% of US children <18 years of age had reported food allergy. The prevalence of reported food allergy increased 18% (z = 3.4; P < .01) from 1997 through 2007. In 2005–2006, serum immunoglobulin E antibodies to peanut were detectable for an estimated 9% of US children. Ambulatory care visits tripled between 1993 and 2006 (P < .01). From 2003 through 2006, an estimated average of 317000 food allergy-related, ambulatory care visits per year (95% confidence interval: 195000–438000 visits per year) to emergency and outpatient departments and physicians offices were reported. Hospitalizations with any recorded diagnoses related to food allergy also increased between 1998–2000 and 2004–2006, from an average of 2600 discharges per year to 9500 discharges per year (z = 3.4; P < .01), possibly because of increased use of food allergy V codes. CONCLUSION: Several national health surveys indicate that food allergy prevalence and/or awareness has increased among US children in recent years.

The effect of birth weight discordance on twin neonatal mortality

OBJECTIVE To estimate the association between birth weight discordance and neonatal mortality controlling for the effects of fetal growth, and to understand the differences in the incidence of mortality between larger and smaller infants. METHODS This analysis is based on the National Center for Health Statistics matched multiple birth data set file containing all twin births in the United States from 1995 through 1997. Birth weight discordance was grouped into four levels (15–19%, 20–24%, 25–29%, and 30% or more). Generalized estimating equations were used to obtain adjusted odds ratios and 95% confidence intervals to estimate the mortality risk associated with discordance after adjusting for fetal growth. RESULTS Mortality was 11 times higher among highly discordant smaller twins (30% or more) compared with nondiscordant smaller twins (43.4 and 3.8 per 1000, respectively). Risk estimates ranged from 1.08 (95% confidence interval 0.85, 1.38) among 15–19% discordant twins to 2.05 (95% confidence interval 1.66, 2.51) among 30% or more discordant twins. Larger twins had similar risk estimates. After accounting for the association between fetal growth and discordance, mortality risk was substantially higher among smaller and larger twins who were highly discordant (30% or more). In addition, there was little difference in the magnitude of risk estimates between highly discordant smaller and larger twins. CONCLUSION After controlling for fetal growth, smaller and larger twins affected by higher levels of birth weight discordance (25% or more) remain at disproportionate risk for neonatal mortality when compared with other smaller or larger twins. Additionally, smaller twins do not have an elevated risk compared with larger twins after adjusting for their different fetal growth distributions.

Dietary Supplement Use and Folate Status during Pregnancy in the United States

Adequate folate and iron intake during pregnancy is critical for maternal and fetal health. No previous studies to our knowledge have reported dietary supplement use and folate status among pregnant women sampled in NHANES, a nationally representative, cross-sectional survey. We analyzed data on 1296 pregnant women who participated in NHANES from 1999 to 2006 to characterize overall supplement use, iron and folic acid use, and RBC folate status. The majority of pregnant women (77%) reported use of a supplement in the previous 30 d, most frequently a multivitamin/-mineral containing folic acid (mean 817 μg/d) and iron (48 mg/d). Approximately 55-60% of women in their first trimester reported taking a folic acid- or iron-containing supplement compared with 76-78% in their second trimester and 89% in their third trimester. RBC folate was lowest in the first trimester and differed by supplement use across all trimesters. Median RBC folate was 1628 nmol/L among users and 1041 nmol/L among nonusers. Among all pregnant women, median RBC folate increased with trimester (1256 nmol/L in the first, 1527 nmol/L in the second, and 1773 nmol/L in the third). Given the role of folic acid in the prevention of neural tube defects, it is notable that supplement use and median RBC folate was lowest in the first trimester of pregnancy, with 55% of women taking a supplement containing folic acid. Future research is needed to determine the reasons for low compliance with supplement recommendations, particularly folic acid, in early pregnancy.

The Contribution of Preterm Birth to the Black–White Infant Mortality Gap, 1990 and 2000

OBJECTIVES We evaluated whether the decline of the racial disparity in preterm birth during the last decade was commensurate with a decline in the contribution of preterm birth to the infant mortality gap. METHODS We used linked files of 1990 and 2000 data on US infant births and deaths to partition the gap between Black and White infant mortality rates into differences in the (1) distribution of gestational age and (2) gestational age-specific mortality rates. RESULTS Between 1990 and 2000, the Black-White infant mortality rate ratio did not change significantly (2.3 vs 2.4). Excess deaths among preterm Black infants accounted for nearly 80% of the Black-White infant mortality gap in both 1990 and 2000. The narrowing racial disparity in the preterm birth rate was counterbalanced by greater mortality reductions in White than in Black preterm infants. Extremely preterm birth (<28 weeks) was 4 times higher in Black infants and accounted for more than half of the infant mortality gap. CONCLUSIONS Substantial reductions in the Black-White infant mortality gap will require improved prevention of extremely preterm birth among Black infants.

Trends in Caffeine Intake Among US Children and Adolescents

BACKGROUND AND OBJECTIVE: Physicians and policy makers are increasingly interested in caffeine intake among children and adolescents in the advent of increasing energy drink sales. However, there have been no recent descriptions of caffeine or energy drink intake in the United States. We aimed to describe trends in caffeine intake over the past decade among US children and adolescents. METHODS: We assessed trends and demographic differences in mean caffeine intake among children and adolescents by using the 24-hour dietary recall data from the 1999–2010 NHANES. In addition, we described the proportion of caffeine consumption attributable to different beverages, including soda, energy drinks, and tea. RESULTS: Approximately 73% of children consumed caffeine on a given day. From 1999 to 2010, there were no significant trends in mean caffeine intake overall; however, caffeine intake decreased among 2- to 11-year-olds (P < .01) and Mexican-American children (P = .003). Soda accounted for the majority of caffeine intake, but this contribution declined from 62% to 38% (P < .001). Coffee accounted for 10% of caffeine intake in 1999–2000 but increased to nearly 24% of intake in 2009–2010 (P < .001). Energy drinks did not exist in 1999–2000 but increased to nearly 6% of caffeine intake in 2009–2010. CONCLUSIONS: Mean caffeine intake has not increased among children and adolescents in recent years. However, coffee and energy drinks represent a greater proportion of caffeine intake as soda intake has declined. These findings provide a baseline for caffeine intake among US children and young adults during a period of increasing energy drink use.

Relationship of maternal body mass index and height to twinning.

OBJECTIVE: Increasing use of fertility drugs is considered the primary cause for the recent increase in dizygotic twinning in developed countries. However, dizygotic twinning has also been related to obesity in foreign populations. We sought to confirm this relationship in U.S. pregnancies, which predated widespread use of fertility drugs. METHODS: We analyzed 51,783 pregnancies (561 twin) in the Collaborative Perinatal Project, which took place at 12 hospitals in the United States from 1959 to 1966. The occurrence of twinning was compared according to maternal self-reported prepregnant body mass index (BMI) of less than 20, 20–24.99, 25–29.99, and 30 kg/m2 or greater, before and after adjustment for confounding factors. RESULTS: There was a statistically significant trend for increased risk of total twinning with increasing BMI (P < .001). The odds of monozygous twinning were not significantly related to BMI, but the odds of dizygous twinning were significantly related to increased BMI. After adjusting for maternal race, age, parity, and height, the odds of dizygous twinning were still significantly elevated among women with a BMI of 30 or more, and the trend for increasing risk of dizygous twinning with increasing BMI was significant (P = .001). The trend for increased twinning with increasing height was also significant. Women in the tallest quartile of height had a significantly increased odds ratio for dizygous twin pregnancies, although not of the same magnitude as women with BMI over 30. CONCLUSION: We confirmed the association of maternal weight and height with dizygotic twinning in a U.S. population among which fertility drugs were not a factor. LEVEL OF EVIDENCE: II-2

Prepregnancy Body Mass Index and Gestational Weight Gain in Relation to Child Body Mass Index Among Siblings

There is increasing evidence that in utero effects of excessive gestational weight gain may result in increased weight in children; however, studies have not controlled for shared genetic or environmental factors between mothers and children. Using 2,758 family groups from the Collaborative Perinatal Project, the authors examined the association of maternal prepregnancy body mass index (BMI) and gestational weight gain on child BMI at age 4 years using both conventional generalized estimating equations and fixed-effects models that account for shared familial factors. With generalized estimating equations, prepregnancy BMI and gestational weight gain had similar associations with the child BMI z score (β = 0.09 units, 95% confidence interval (CI): 0.08, 0.11; and β = 0.07 units, 95% CI: 0.04, 0.11, respectively. However, fixed effects resulted in null associations for both prepregnancy BMI (β = 0.03 units, 95% CI: -0.01, 0.07) and gestational weight gain (β = 0.03 units, 95% CI: -0.02, 0.08) with child BMI z score at age 4 years. The positive association between gestational weight gain and child BMI at age 4 years may be explained by shared family characteristics (e.g., genetic, behavioral, and environmental factors) rather than in utero programming. Future studies should continue to evaluate the relative roles of important familial and environmental factors that may influence BMI and obesity in children.

Maternal Body Mass Index and Daughters' Age at Menarche

Background: The role of intergenerational influences on age at menarche has not been explored far beyond the association between mothers’ and daughters’ menarcheal ages. Small size at birth and childhood obesity have been associated with younger age at menarche, but the influence of maternal overweight or obesity on daughters’ age at menarche has not been thoroughly examined. Methods: In a follow-up study of the prospective Collaborative Perinatal Project, grown daughters were asked in 1987–1991 for their age at menarche. Data from the original Collaborative Perinatal Project (1959–1966) included their mothers’ height and prepregnancy weight. In the follow-up study, 597 of 627 daughters had complete menarche and maternal data available and were included in the present analysis. We used polytomous logistic regression to examine the association between maternal overweight (body mass index [BMI] = 25–29.9 km/m2) or obesity (BMI ≥ 30) and daughters age at menarche (≤12, 12, 13, 14+ years). Results: Compared with those whose mothers had a BMI less than 25, daughters of obese mothers experienced younger age at menarche (OR for menarche at ≤12 years = 3.1 [1.1–9.2]). This association remained after adjusting for maternal age at menarche, maternal parity, socioeconomic status, race, and study site (OR = 3.3 [1.1–10.0]). Effect estimates for maternal overweight were close to the null. There was limited evidence of mediation by small for gestational age or BMI at age 7. Conclusions: Maternal obesity is associated with younger menarcheal age among daughters in this study, possibly via unmeasured shared factors.

The contribution of mixed dishes to vegetable intake among US children and adolescents

OBJECTIVE To describe the contribution of mixed dishes to vegetable consumption and to estimate vegetable intake according to specific types of vegetables and other foods among US children and adolescents. DESIGN The 2003-2008 National Health and Nutrition Examination Survey (NHANES), a nationally representative probability survey conducted in the USA. SETTING Civilian non-institutionalized US population. SUBJECTS All children and adolescents aged 2-18 years who met eligibility criteria (n 9169). RESULTS Approximately 59 % of total vegetable intake came from whole forms of vegetables with 41 % coming from a mixed dish. White potatoes (10·7 (SE 0·6) %), fried potatoes (10·2 (SE 0·4) %), potato chips (8·6 (SE 0·5) %) and other vegetables (9·2 (SE 0·5) %) accounted for most vegetables in their whole forms, whereas pasta dishes (9·5 (SE 0·4) %), chilli/soups/stews (7·0 (SE 0·5) %), pizza/calzones (7·6 (SE 0·3) %) and other foods (13·7 (SE 0·6) %) accounted for most mixed dishes. Usual mean vegetable intake was 1·02 cup equivalents/d; however, after excluding vegetables from mixed dishes, mean intake fell to 0·54 cup equivalents/d and to 0·32 cup equivalents/d when fried potatoes were further excluded. CONCLUSIONS Mixed dishes account for nearly half of overall vegetable intake in US children and adolescents. It is critical for future research to examine various components of vegetable intake carefully in order to inform policy and programmatic efforts aimed at improving dietary intake among children and adolescents.

Dietary intake of polyunsaturated fatty acids and fish among US children 12–60 months of age

UNLABELLED This study aimed to estimate intake of individual polyunsaturated fatty acids (PUFAs), identify major dietary sources of PUFAs and estimate the proportion of individuals consuming fish among US children 12-60 months of age, by age and race and ethnicity. The study employed a cross-sectional design using US National Health and Nutrition Examination Survey data. Representative sample of US population based on selected counties. SUBJECTS 2496 US children aged 12-60 months. Mean daily intake of n-6 PUFAs and eicosapentaenoic acid (EPA) varied by age, with children 12-24 months of age having lower average intakes (mg or g day(-1) ) than children 49-60 months of age and the lowest n6 : n3 ratio, upon adjustment for energy intake. Docosahexaenoic acid (DHA) intake was low (20 mg day(-1) ) compared to typical infant intake and did not change with age. Compared to non-Hispanic white children, Mexican American children had higher DHA and arachidonic acid (AA) intake. In the previous 30 days, 53.7% of children ever consumed fish. Non-Hispanic black children were more likely than non-Hispanic white children to have consumed fish (64.0% vs. 53.0%). Results indicate low prevalence of fish intake and key n-3 PUFAs, relative to n-6 fatty acids, which suggests room for improvement in the diets of US children. More research is needed to determine how increasing dietary intakes of n-3 PUFAs like DHA could benefit child health.