Neonatal Anthropometry
Luis Pereira-da-Silva
Clínica Universitária de Pediatria, Hospital de Dona Estefânia,
Faculdade de Ciências Médicas, Universidade Nova de Lisboa.
2008
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
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
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
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
DIRECT MEASURES
Weight
More used measure
Good accuracy and
reproducibility
Incubators incorporating
weighing scales
However, weight do not
estimate the body
compartments…
Gibson. Horm Res 2003
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…
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
Crown-heel length
measurement
New method of measurement:
Extending only one lower
limb discomfort
significantly reduced,
easier
Pereira-da-Silva. Acta Paediatr 2006
Head circumference
Reflects the brain
growth
Freedman. Science 1980
Mid-arm circumference
Reflects the sum of fat and
muscle arm compartments
rough indicator of body
fat and protein reserves
Georgieff. Clin Perinatol 1986
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
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
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
DERIVED MEASURES
INDICES
based on Weight and Length
1.
Ponderal index (W / L3) x100
2.
Adiposity index - body mass index (W / L2)
3.
Weight/ length ratio (W / L)
4.
Benn index (W / Ln)
5.
Individualized birthweight ratio
Tamim. J Perinat Med 2004
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
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 = MAC2 / 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
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
fat area 1
muscle area 1
Case 2
>
<
fat area 2
muscle area 2
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.
AJCN 1997
Rolland-Cachera.
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. 1998
But not validated…
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
Upper arm cross-sectional areas
Preterm infants (appropriate-forgestational-age):
Validated by MRI
measurements both
direct and derived upperarm anthropometry are
inaccurate predictors
(r2<0.56) of arm
compartments.
Pereira-da-Silva. Neonatology 2008
Neonatal anthropometry
as clinical tool
in IUGR
Neonatal anthropometry
as clinical tool
AT BIRTH:
I.
DIAGNOSIS OF FETAL MALNUTRITION AND
PREDICTION OF EARLY METABOLIC RISK
Measures
Weight
Ponderal index
MAC:HC ratio
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
Ponderal Index (PI)
W / L3 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
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
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
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
Neonatal anthropometry
as clinical tool
NEONATAL AND POST-NEONATAL PERIOD:
II.
ASSESSMENT OF NUTRITIONAL STATUS
(BODY COMPOSITION)
Measures
Weight
Length
MAC
Skinfolds…
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…)
http://pediatrics.aappublications.org/cgi/content/full/104/2/280
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)
http://www.biomedcentral.com/1471-2431/3/13
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
Neonatal anthropometry
as clinical tool
NEONATAL PERIOD:
III.
PREDICTION OF LATE METABOLIC RISK
(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
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
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
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
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
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
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
Conclusions
Validated anthropometric measures for nutritional
assessment in the neonate are scarce
Any further validated measure will be welcome!
More research…
Thank you