Judy M. Hopkinson

Body Composition during the First 2 Years of Life: An Updated Reference

Normative body composition during the first 2 y of life was derived from a prospective study of 76 children. We present 1) fat free mass (FFM) and its components, and fat mass (FM), 2) incremental growth rates partitioned into chemical components, and 3) age-specific and gender-specific constants for converting chemical and physical components into FFM for children during the first 2 y of life. A multicomponent model based on measurements of total body water (TBW), total body potassium (TBK) and bone mineral content (BMC) was used to estimate FFM and FM at 0.5, 3, 6, 9, 12, 18, and 24 mo of age. TBW was determined by deuterium dilution, TBK by whole body counting, and BMC by dual energy x-ray absorptiometry. FFM was higher in boys than girls between 0.5–18 mo of age (p ≤ 0.05). Percent FM increased on average from 13 to 31% between 0.5 and 3–6 mo, and then gradually declined. Percent FM was significantly higher in girls than in boys at 6 and 9 mo of age (p ≤ 0.02). The components of FFM on a percentage basis changed with age (p = 0.001), but not gender. The protein content of FFM increased gradually with age, while TBW declined (p = 0.001). As a percentage of FFM, osseous mineral increased from 2.0 to 3.4% in boys and from 2.1 to 3.3% in girls between 0.5 and 24 mo (p = 0.001). Density and potassium content of FFM increased gradually with age (p = 0.001). These normative body composition data provide an updated reference upon which to assess normal growth and nutritional status of pediatric populations representative of mixed feeding groups during the first 2 y of life.

Composition of gestational weight gain impacts maternal fat retention and infant birth weight

OBJECTIVE The purpose of this study was to evaluate how changes in gestational weight and body composition affect infant birth weight and maternal fat retention after delivery in underweight, normal-weight and overweight women. STUDY DESIGN We assessed the body composition of 63 women (low body mass index, 17 women; normal body mass index, 34 women; and high body mass index, 12 women) on the basis of measurements of total body nitrogen by prompt-gamma activation analysis, total body potassium by whole body counting, and a multicomponent model based on total body water by deuterium dilution, body volume by densitometry, and bone mineral content by dual energy x-ray absorptiometry (DXA) before pregnancy, at 9, 22, and 36 weeks of gestation, and at 2, 6, and 27 weeks after delivery. Infant weight and length were recorded at birth; infant anthropometry and body composition by DXA were assessed at 2 and 27 weeks of age. RESULTS Gestational weight gain was correlated significantly with gains in total body water, total body potassium, protein, fat-free mass, and fat mass (P=.001-.003). Gains in total body water, total body potassium, protein and fat-free mass did not differ among body mass index groups; however, fat mass gain was higher in the high body mass index group (P=.03). Birth weight was correlated positively with gain in total body water, total body potassium, and fat-free mass (P<.01), but not fat mass. Postpartum weight and fat retention were correlated positively with gestational weight gain (P=.001) and fat mass gain (P=.001) but not with total body water, total body potassium, or fat-free mass gain. CONCLUSION Appropriate, but not excessive, gestational weight gain is needed to optimize infant birth weight and minimize maternal postpartum fat retention.

Development of the Responsiveness to Child Feeding Cues Scale

Parent-child feeding interactions during the first 2 years of life are thought to shape child appetite and obesity risk, but remain poorly studied. This research was designed to develop and assess the Responsiveness to Child Feeding Cues Scale (RCFCS), an observational measure of caregiver responsiveness to child feeding cues relevant to obesity. General responsiveness during feeding as well as maternal responsiveness to child hunger and fullness were rated during mid-morning feeding occasions by three trained coders using digital-recordings. Initial inter-rater reliability and criterion validity were evaluated in a sample of 144 ethnically-diverse mothers of healthy 7- to 24-month-old children. Maternal self-report of demographics and measurements of maternal/child anthropometrics were obtained. Inter-rater agreement for most variables was excellent (ICC>0.80). Mothers tended to be more responsive to child hunger than fullness cues (p<0.001). Feeding responsiveness dimensions were associated with demographics, including maternal education, maternal body mass index, child age, and aspects of child feeding, including breastfeeding duration, and self-feeding. The RCFCS is a reliable observational measure of responsive feeding for children <2 years of age that is relevant to obesity.

Maternal decisions about the initiation and termination of infant feeding.

Caregiver responsiveness to infant hunger and fullness cues is thought to play a role in the development of overweight during infancy, but this aspect of infant feeding has received little study. This research used a qualitative approach to understand aspects of feeding responsiveness involving maternal perception and interpretation of infant feeding cues by asking mothers about factors they used to initiate and terminate infant feeding. Participants were 71 ethnically diverse mothers of healthy, term infants at 3, 6, or 12 months of age. Mothers were asked three questions about feeding initiation and termination. Qualitative content analysis was used to derive major themes. Results revealed that the extent to which infant cues were prominent in maternal approaches to feeding was variable. Some mothers focused on amount consumed or eating schedule whereas others reported sole orientation to infant state and/or oral behaviors. Other themes involved the range of intensity and specificity of the infant cues that prompted feeding initiation and termination. The qualitative findings suggest that mothers may differ in the extent to which they perceive and rely upon infant hunger and fullness cues to initiate and terminate feeding.

Fat mass in infants and toddlers: comparability of total body water, total body potassium, total body electrical conductivity, and dual-energy X-ray absorptiometry.

BACKGROUND Accurate assessment of body composition in infants and children is fundamental to understanding normal growth and development. Validation of methods applicable to pediatric populations is needed. In the absence of a gold standard, this study was conducted to compare methods using total body water, total body potassium, total body electrical conductivity, and dual-energy x-ray absorptiometry measurements for the estimation of body fat mass in infants and toddlers. METHODS Repeated body composition measurements were performed on 76 healthy term infants at 0.5, 3, 6, 9, 12, 18, and 24 months of age. Total body water was determined by deuterium dilution and converted to fat-free mass. Total body electrical conductivity was used to measure fat mass. Total body potassium was estimated by whole-body counting and converted to fat-free mass. Dual-energy x-ray absorptiometry was used to estimate fat mass at 0.5, 12, and 24 months only. Data were analyzed by repeated measures analysis of variance, followed by Bonferroni multiple comparisons at 5%. RESULTS Significant differences among methods were encountered at each age (p = 0.001-0.05). The rank order of the methods and the magnitude of the method differences were a function of age, not of gender or infant feeding mode. Wide limits of agreement imply that the methods are not interchangeable for group or individual measurements. CONCLUSIONS Methods using total body water, total body potassium, total body electrical conductivity, and dual-energy x-ray absorptiometry to estimate body fat mass in infants and toddlers are not interchangeable and require further development and validation.

State of the art vitamin K in human milk

Breast-feeding is the sole source of vitamin K for most of the worlds children and breast-fed infants are at risk for vitamin K-responsive hemorrhagic disease of the newborn (HDNB). Recent advances in high performance liquid chromatography methodology have made possible the first quantitative studies of vitamin K in human milk. Although much progress has been made, much remains to be done. Innovative improvements in methodology are needed, as detection of nanogram quantities of vitamin K in milk is at the limit of current methodology. Additional studies are needed over the lactation period. A better understanding of colostrum is needed with regard to other nutrients as well as vitamin K. Vitamin K in the milk of mothers who gave birth prematurely has not been measured. The significance of menaquinones as a vitamin K source to the infant is undetermined. The mechanism regulating vitamin K secretion into milk has not been investigated. The localization of vitamin K in milk is undetermined as is the relationship of vitamin K to other milk lipids. The effects of fat-soluble vitamins in the diet on vitamin K concentrations in milk is unknown. The pharmacokinetics of vitamin K supplementation of mothers is particularly important in cultures where vitamin K is not routinely administered at birth. Finally, most critical at this point is our ignorance about the relationship of the maternal vitamin K status to the vitamin K status of the infant. As breast milk is the sole source of vitamin K for most of the worlds infants, HDNB remains a very real threat to the health of infants and warrants concentrated study.

Assignment to a hospital-based breastfeeding clinic and exclusive breastfeeding among immigrant Hispanic mothers: a randomized, controlled trial.

A randomized controlled trial is used to determine whether assigning mixed feeders to a breastfeeding clinic within 1 week postpartum will increase exclusive breastfeeding at 1 month among Hispanic immigrants. Subjects are eligible for the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC), and 85% are monolingual Hispanic. Mothers (n = 522) of infants at low risk for hyperbilirubinemia are approached at bedside 20 to 48 hours after delivery and randomly assigned to treatment or control groups. Intent-to-treat analysis of feeding behavior at 4 weeks postpartum indicates that the intervention group is more likely to be exclusively breastfeeding (16.4% vs 10% in the control group, P = .03; adjusted odds ratio 1.87; 95% confidence interval, 1.07-3.26); that the incidence of formula supplementation does not differ between groups; and that the intervention group is less likely to supplement with water and tea (P < .002). J Hum Lact. 25(3):287-296.

Changes in fat-free mass and fat mass in postpartum women: a comparison of body composition models

OBJECTIVES: (1) To compare 2-, 3- and 4-component models of body composition based on total body water (TBW), underwater weighing (UWW), skinfold thicknesses (SF), total body potassium (TBK), dual-energy X-ray absorptiometry (DXA) and total body electrical conductivity (TOBEC); (2) to compare postpartum changes in body composition estimated by the 2-, 3- and 4-component models and (3) to test for an effect of pregnancy or lactation on the hydration, density and potassium content of fat free mass (FFM) in postpartum women. DESIGN: Longitudinal measurements of body composition at 3, 6 and 12 months postpartum. SUBJECTS: Thirty-five healthy postpartum women, aged 30.2±3.5 y. MEASUREMENTS: Body composition was estimated by 2-component models based on TBW, UWW, SF, TBK, DXA or TOBEC; 3-component models based on TBW and UWW (Fuller 3, Siri 3); and a 4-component model (Fuller 4) based on TBW, UWW and bone mineral content. RESULTS: Systematic differences were seen among the various body composition models, with the following ranking from lowest to highest estimate of fat mass (FM): TOBEC, TBW, Fuller 3, Siri 3, Fuller 4, UWW, SF, TBK, and DXA. Estimated changes in FFM and FM were not significantly different among methods, except for the 3–6 months FFM and FM changes estimated from TBW, which differed from SF, DXA, and TOBEC. Pregnancy-induced changes in the hydration, density and potassium content of FFM were not evident by 3 months postpartum (0.73±0.02, 1.099±0.015 kg/l and 2.31±0.10 g/kg, respectively). CONCLUSION: In spite of systematic differences among body composition models for the measurement of FFM and FM, changes in FFM and FM did not differ significantly among the models. Since there was no apparent effect of pregnancy or lactation on the postpartum composition of FFM, 2-component models of body composition are acceptable for use in postpartum women beyond the puerperium.

Quantitation of vitamin K in human milk

A quantitative method was developed for the assay of vitamin K in human colostrum and milk. The procedure combines preparative and analytical chromatography on silica gel in a nitrogen atmosphere followed by reversed phase high performance liquid chromatography (HPLC). Two HPLC steps were used: gradient separation with ultraviolet (UV) detection followed by isocratic separation detected electrochemically. Due to co-migrating impurities, UV detection alone is insufficient for identification of vitamin K. Exogenous vitamin K was shown to equilibrate with endogenous vitamin K in the samples. A statistical method was incorporated to control for experimental variability. Vitamin K1 was analyzed in 16 pooled milk samples from 7 donors and in individual samples from 15 donors at 1 month post-partrum. Vitamin K1 was present at 2.94±1.94 and 3.15±2.87 ng/mL in pools and in individuals, respectively. Menaquinones, the bacterial form of the vitamin, were not detected. The significance of experimental variation to studies of vitamin K in individuals is discussed.

Energy requirements from infancy to adulthood

To investigate how age and body composition affect energy requirements, the sedentary daily expenditure (SDE) and basal metabolic rate (BMR) of 101 infants, 82 girls, and 27 adults were measured. Energy expenditure was scaled for differences in body size to test the effects of age and body fatness. A power function was superior to linear models. For all subjects, WT0.63 (where WT is weight) or FFM0.63 (where FFM is fat-free mass) explained 94% of the variability in BMR, and WT0.70 or FFM0.70 explained 97% of the variability in SDE. The effects of height and fat mass (kg or % body wt) on BMR and SDE scaled for weight or fat-free mass were age dependent. Best-fitted exponents relating BMR or SDE to body size differed between children (0.40-0.52) and infants (1.04-1.30) (P = 0.001). Human energy requirements from infancy to adulthood appear to be a power, not a linear, function of body weight and composition.