Neonatal Anthropometry Luis Pereira-da-Silva

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1 Neonatal Anthropometry Luis Pereira-da-Silva Clínica Universitária de Pediatria, Hospital de Dona Estefânia, Faculdade de Ciências Médicas, Universidade Nova de Lisboa. 2008

2 Anthropometry DEFINITION: quantitative expression of the body s form - measurements of the human body and its parts. A clinical tool, including in Neonatal Medicine Prins. Pediatric Rev Commun 1995

3 Anthropometry as a method Advantages: Easy to perform, inexpensive and noninvasive method convenient for bedside measurements. Lafeber. Clin Perinatol 1999, Pereira-da-Silva. Pediatr Nutr (ISPEN) 2002 Disadvantages: Indirect method with several limitations, including its low reliability. De Bruin. AJCN 1995

4 Neonatal anthropometry For any clinical measurement recommended appropriate: technique + reference values + interpretation Technique - validated: accuracy + precision + reliability + repeatability Reference values: local standards or international references? Describing how infants grow rather than describing how infants should grow? Garza. Food Nutr Bull 2004 Interpretation factors influencing: gender, ethnic group, type of feeding, secular trend, accurate gestational age

5 Neonatal anthropometry Direct measures: weight, crown-heel length, head circumference (HC), mid-arm circumference (MAC), skinfold thickness Derived measures: ponderal index, body mass index, MAC/HC, mid-arm cross-arm areas Pereira-da-Silva. Nestlé Nutr Inst (Portugal) 2007

6 DIRECT MEASURES

7 Weight More used measure Good accuracy and reproducibility Incubators incorporating weighing scales However, weight do not estimate the body compartments Gibson. Horm Res 2003

8 Crown-heel length Global indicator of lean body mass; Reflects the skeletal growth Koo. J Nutr 2000; Gibson. Horm Res 2003 Accurate length measurement: important when length is squared or cubed in equations (body mass index, ponderal index) However Difficulty in measuring the length accurately

9 Crown-heel length measurement Conventional method: difficulty in extending the lower limbs affects the accuracy: discomfort (NFCS score) caused by full extension - similar to heel-stick Pereira-da-Silva. Acta Paediatr 2006

10 Crown-heel length measurement New method of measurement: Extending only one lower limb discomfort significantly reduced, easier Pereira-da-Silva. Acta Paediatr 2006

11 Head circumference Reflects the brain growth Freedman. Science 1980

12 Mid-arm circumference Reflects the sum of fat and muscle arm compartments rough indicator of body fat and protein reserves Georgieff. Clin Perinatol 1986

13 Skinfold thickness Estimates the subcutaneous fat, assuming that the site measured represents the mean thickness of the subcutaneous fat layer More used: triceps and biceps (peripheral), subscapular and suprailiac (central). Lukaski. Am J Clin Nutr 1987

14 Skinfold thickness Skinfold thickness as estimator of total body fat (TBF): Reasonable correlation between skinfold measurements and TBF (DEXA). Schmelzle. Am J Clin Nutr 2002, Koo. Pediatr Res 2004 Poor correlation between skinfold measurements and TBF. Lapillonne. J Pediatr Endocrinol Metab 1999, Olhager. Acta Paediatr 2006

15 Skinfold thickness Skinfold thickness estimating total body fat limitations: Skinfold thickness do not reflect internal (intrabdominal) fat Rapid changes of fat distribution in neonatal period Hydration may influence the compressibility of skinfolds Skinfold measurements require expertise and experience (high inter-observer variability) Prins. Pediatric Rev Commun 1995

16 DERIVED MEASURES

17 INDICES based on Weight and Length 1. Ponderal index (W / L 3 ) x Adiposity index - body mass index (W / L 2 ) 3. Weight/ length ratio (W / L) 4. Benn index (W / L n ) 5. Individualized birthweight ratio Tamim. J Perinat Med 2004

18 Mid-arm circumference/ Head circumference (MAC:HC) ratio HC is used in denominator as a constant : the brain is usually spared during acute malnutrition Freedman. Science 1980 < MAC : reflects acute fat and protein consumption Sasanow. J Pediatr 1986

19 Upper arm cross-sectional areas Equations based on mid-arm circumference (MAC) and tricipital skinfold thickness (TS) estimating total arm area (AA), arm muscle area (AMA), and arm fat area (AFA): AA = MAC 2 / 4π; AMA = (MAC πts) / 4π; AFA = AA - AMA. Jelliffee. J Trop Pediatr 1969 AFA = MAC x TS/2; AMA = AA AFA. Rolland-Cachera. AJCN 1997

20 Upper arm cross-sectional areas May represent better estimators of the relative contribution of fat and muscle to the total arm area than MAC and TSF used alone Georgieff. J Pediatr 1989, Hediger. Pediatrics 1998 For the same mid-arm circumference (MAC): Case 1 Case 2 fat area 1 > muscle area 1 < fat area 2 muscle area 2

21 Upper arm cross-sectional areas Have been validated by using image methods (CT scan and MRI): In adults. Heymsfield. Am J Clin Nutr 1982 In adolescents and children >9 yrs. Rolland-Cachera. AJCN 1997

22 Upper arm cross-sectional areas In neonates and small infants: Reference values have been published. Sann. Arch Dis Child 1988 Used in nutritional assessment. Georgieff. J Pediatr 1989, Hediger. Arch Pediatr Adolesc Med But not validated

23 Upper arm cross-sectional areas Healthy full-term neonates: Anthropometry - poor correlation with ultrasound measurements; anthropometry overestimates muscle area and underestimates fat area Both methods have limitations Pereira-da-Silva. Early Hum Dev 1999

24 Upper arm cross-sectional areas Preterm infants (appropriate-forgestational-age): Validated by MRI measurements both direct and derived upperarm anthropometry are inaccurate predictors (r 2 <0.56) of arm compartments. Pereira-da-Silva. Neonatology 2008

25 Neonatal anthropometry as clinical tool in IUGR

26 Neonatal anthropometry as clinical tool AT BIRTH: I. DIAGNOSIS OF FETAL MALNUTRITION AND PREDICTION OF EARLY METABOLIC RISK

27 Measures Weight Ponderal index MAC:HC ratio

28 Weight Kramer MS, et al. Pediatrics 2001;108:e35 Weight < > gestational age < > gender Centiles 3th to 97th Mean and SD (great deviations: > -2SD or +2SD) Small-for-gestational age (SGA) predictor of: hypothermia, hypoglycemia, hypocalcaemia, necrotizing enterocolitis (preterm) Large-for-gestational age (LGA) predictor of: hypoglycemia, hypocalcaemia, polycythemia Constitutional LIG and GIG

29 Ponderal Index (PI) W / L 3 x100 Used to distinguish the types of IUGR: Restriction late in gestation Normal neonate normal PI only the weight affected low PI: Asymmetrical IUGR Restriction early in gestation low PI Asymmetrical IUGR weight + length affected normal PI: Symmetrical IUGR normal PI Symmetrical IUGR

30 Ponderal index Lubchenco L, et al. Pediatrics 1966;37:265 Limitations: older homogenous data sets, smaller sample sizes, varying age ranges, combined-gender curves and/or disparate data sources Groveman SA. Thesis 2008 Nevertheless, more objective classification of asymmetrical / symmetrical IUGR: centiles for Ponderal Index

31 Ponderal index Asymmetrical IUGR predictor of: asphyxia, hypothermia, hypoglycemia and hypocalcaemia Symmetrical IUGR (sometimes <HC) predictor of: poor growth and neurodevelopment outcome Berg. Early Hum Dev 1989, Fay. Aust N Z J Obstet Gynecol 1991

32 MAC:HC ratio < MAC:HC ratio: Specially useful in the diagnosis of growth retarded AGA infants (weight still >10th centile) Sasanow. J Pediatr 1986 Better predictor of early metabolic risk and hypothermia than the Ponderal Index Chang. Early Hum Dev 1993

33 Neonatal anthropometry as clinical tool NEONATAL AND POST-NEONATAL PERIOD: II. ASSESSMENT OF NUTRITIONAL STATUS (BODY COMPOSITION)

34 Measures Weight Length MAC Skinfolds

35 Neonatal period (preterm infants) Ehrenkranz RA et al. Pediatrics 1999;104:280 Recent, reflecting the current practice Based on a large sample (12 US NICUs) Include: weight, length, HC and MAC Specific values for SGA, and major morbidities (HMD, NEC, BPD )

36 Post-neonatal period (preterm infants) Fenton TR. BMC Pediatr 2003;3:1 Updated Babson & Benda 1976 growth charts Curves for post-discharge (up to 50 wks GA) assessment of weight, length (lean body mass), and HC (brain)

37 Skinfolds < Skinfold thickness assessment of fat body mass, guidance for nutritional strategy Beattie. Br J Obstet Gynecol 1994 Reference values for neonates Rodriguez. Eur J Pediatr 2004 Deserve further validation Olhager. Acta Paediatr 2006, Pereira-da-Silva. Neonatology 2008

38 Neonatal anthropometry as clinical tool NEONATAL PERIOD: III. PREDICTION OF LATE METABOLIC RISK

39 (Barker theory) FETAL MALNUTRITION Permanent intrauterine structural and functional changes ( programming ) Neonatal anthropometrical predictors: fetal malnutrition + Post-neonatal anthropometrical predictors: rapid catch-up growth Insulin resistance Obesity, cardiovascular disease, hypertension, dyslipidaemia, type 2 diabetes LATE METABOLIC DISEASE

40 Anthropometry at birth WEIGHT LBW and VLBW risk of glucose intolerance and late metabolic syndrome (MS) Barker. Diabetologia 1993, Pandolfi Metabolism 2008 LGA and Macrosomia risk of late MS McCance. BMJ 1994, Wang. Indian J Pediatr 2007

41 Anthropometry at birth LBW, SGA, asymmetrical IUGR The birth weight does not tell us the whole story of what will happen after birth Uauy (comment). In: Nestle Nutr Work Series 2005

42 Anthropometry at birth plus Anthropometric evolution LBW + weight deficit during 0-2 yrs insulin resistance and coronary disease in adulthood Barker. NEJM 2005 LBW + catch-up growth 0-6 months hypertension in adulthood McCarthy. Pediatr Res 2001 SGA + catch-up growth 0-3 yr late insulin resistance + central adiposity Soto. J Clin Endocrinol Metab 2003, Mericq. Diabetologia 2005

43 Anthropometry at birth plus Anthropometric evolution Asymmetrical IUGR plus Catch-up growth 0-2 yrs BMC and central adiposity at 5 yrs Ong. BMJ 2000 Adiposity rebound (BMI) >1 yr insulin resistance and central adiposity in adulthood Ezzahir. Pediatr Res 2005 Adiposity rebound (BMI) 7-15 yrs coronary disease in adulthood Eriksson. BMJ 1999

44 Anthropometry at birth WEIGHT Since Barker theory (1989) - dozens of observational studies associating LBW, SGA, asymmetrical IUGR with late MS Several contradictory results association does not mean causation! Recent studies: Birth weight strongly predictive of later lean mass; weaker association with later fatness; Association of LBW with later central adipose distribution controversial, require confirmation Wells. Proc Nutr Soc 2007

45 Conclusions NEONATAL ANTHROPOMETRY In IUGR - a clinical tool for: I. Diagnosis of fetal malnutrition and prediction of early metabolic risk II. Assessment of nutritional status and growth while in the nursery and after discharge (preterm) III. Prediction of late metabolic risk Pereira-da-Silva. Nestlé Nutr Inst (Portugal) 2007

46 Conclusions Validated anthropometric measures for nutritional assessment in the neonate are scarce Any further validated measure will be welcome! More research

47 Thank you