Introduction to Growth and Development: Nutr 526 Intrauterine growth and nutrient accretion Body...
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Transcript of Introduction to Growth and Development: Nutr 526 Intrauterine growth and nutrient accretion Body...
Introduction to Growth and Development: Nutr 526
Intrauterine growth and nutrient accretion
Body Composition Development
Metabolic Physiologic neurologic
Growth
Fetal Growth from 25-40 weeks GA
Weight increases 4-fold Length and OFC increase 2-fold
Determinants of fetal growth
Genetics Maternal/paternal genes, race, sex
estimated to account for 20% of variance in birth weight
Environmental factors
Body Composition BMI and percentage of body weight
made up of fat increase rapidly during the first months of life Fat accounts for 0.5% of body weight
at the fifth month of fetal growth and 16% at term.
3rd trimester: increase from 1-3% of body weight to 10-16% of body weight at term
After birth, fat accumulates rapidly until approximately 9 months of age
Minerals
Two-thirds of mineral content of full-term newborn is accummulated in the last trimester of pregnancy.
Age-related changes in body composition. (Reprinted by permission ofMosby Year Book. Heird WC, Driscoll JM, Schullinger JN, et al.Intravenous alimentation in pediatric patients. J Pediatr 80:351, 1972.)
Energy Reserves
Birthweight Non protein kcal Total kcal
500 50 225
800 grams 125 435
1000 grams 165 600
1500 425 1120
2000 1050 1975
3500 4175 5924
Environmental factors Maternal health Nutrition
Glucose, fatty acids, amino acids for tissue deposition and fuel for oxidative purposes
Ability of maternal-placental system to transfer nutrients to fetus
Endocrine environment E.g. LGA infant:
glucose-insulin-growth factors
GROWTH IN FIRST 12 MONTHS From birth to 1 year of age, normal human
infants triple their weight and increase their length by 50%.
Growth in the first 4 months of life is the fastest of the whole lifespan - birthweight usually doubles by 4 months
4-8 months is a time of transition to slower growth
By 8 months growth patterns more like those of 2 year old than those of newborn.
Weight Gain in Grams per Day in One Month Increments - Girls
Age 10th
percentile50th
percentile90th
percentileUp to 1month
16 26 36
1-2months
20 29 39
2-3months
14 23 32
4-5months
13 16 20
5-6months
11 14 18
Guo et al., J Peds. 1991
Weight Gain in Grams per Day in One Month Increments - Boys
Age 10th
percentile50th
percentile90th
percentileUp to 1month
18 30 42
1-2months
25 35 46
2-3months
18 26 36
3-4months
16 20 24
4-5months
14 17 21
5-6months
12 15 19
Guo et al., J Peds. 1991
Weight gain of Breast fed vs bottle fedinfants: 8-112 days of age (g/d)
Breast fed Bottle fed
Male 29.8 + 5.8 32.2 + 5.6
Female 26.2 + 5.6 27.5 + 4.9
Nelson et al Early Human Development 19:223 1989
Body Composition BMI and percentage of body weight
made up of fat increase rapidly during the first months of life Fat accounts for 0.5% of body weight
at the fifth month of fetal growth and 16% at term.
After birth, fat accumulates rapidly until approximately 9 months of age
Individual Growth Patterns
Weight and length at term appear to be primarily determined by nongenetic maternal factors
Birth weigh and birth length weakly correlate with subsequent weight and length values
Individual Growth Patterns, cont.
African American males and females are smaller than whites at birth, but they grow more rapidly during the first 2 years
Patterns of growth in breastfed infants are different from formula fed infants
Rates of gain for breastfed and formula fed infants during early months of life generally have been found to be similar although some reports have demonstrated greater gains by breastfed infants and others have shown greater gains by formula fed infants
Growth Assessment
Assessment
Screening identifies nutritional risk Nutrition Assessment
Uses information gathered in screening Adds more in depth, comprehensive
data Interprets data Develops care plan Reassess
Challenges
Information Availability,
sufficiency, accuracy Interpretation
Goals, expectation, “does it make sense”
Questions What are goals and
expectations, “does it make sense”
Growth Concerns
Underweight
Short stature
Overweight
A variety of growth references were developed and and used
in the U.S. since the early 1900’s
Intrauterine/Fetal Standards
Lubchenco Based on birth measurements (weight,
length, OFC) N= 5600 caucasian infants born in
Denver 1948=1961 Does not account for postnatal weight
loss due to fluid adjustments with birth Effect of high altitude
Intrauterine/Fetal Growth Standards
Data Sets: Kramer et al: 676,605 infants 22-43 weeks Nicholson et al : 376,000 Swedish infants
28-40 weeks Breeby et al: OFC (N=29090) and Length
(N=26,973) 22-40 weeks CDC Data
Time period 1963-2001
Postnatal Growth Charts
Accounts for initial weight loss Dancis: Data 1948, very small
sample size in lowest weight group Ehrenkranz: Pediatrics 1999:104:280
N=1660 14-16 g/kg/d weight gain 0.9 cm/week increase length 0.35 cm/week increase OFC
Growth references: timeline Stuart/Meredith
Growth Charts (1946-76)
Caucasian, Boston/Iowa city, small sample size
NCHS growth charts (1976-1978)
NCHS AAP/MCHB study
group Used cross sectional
data from NHES, NHANES, and FELs (infant)
CDC produced normalized version
1978 WHO recommended international use
Growth reference timeline: continued
2000 CDC growth charts: revision of NCHS growth charts
2006 WHO released new international growth standards
Assessment of Growth
Growth Charts CDC/NCHS
http://www.cdc.gov/growthcharts/ World Health Organization
http://www.who.int/childgrowth/en
Specialized growth charts Patterns, rates, velocity
NCHS growth charts: Concerns Infant data: Fels study
Primarily formula fed Underrepresented groups: largely
caucasian, middle class Intervals of measurements (q3
months from 3-36 months) may not define dynamic patterns during rapid growth phases
Statistical smoothing proceedures
CDC Growth charts: 2000
Based on 5 cross sectional nationally representative surveys between 1963 and 1995
Included more breastfed infants
CDC/NCHS Growth Charts
Data from previous NCHS charts came from private study of primarily white, formula-fed, middle-class infants from southwestern Ohio before 1975
Newer charts have more representative data (some breastfeed and ethnic diversity) from NHANES and use more sophisticated smoothing techniques
16 new charts provided by gender and age
CDC Growth Charts (compared to older NCHS
Standardized data collection methods
Expanded sample Exclusions
VLBW infants NHANES III weight data for >6 year
olds
CDC Growth Charts (compared to older NCHS
Standardized data collection methods
Expanded sample Exclusions
VLBW infants NHANES III weight data for >6 year
olds
CDC/NCHS Growth Charts
Clinical charts for infancy for girls and boys: weight length weight for length OFC
Choice between outer limits at 3rd and 97th or 5th and 95th percentiles
Adam
Adam
Carl
WHO Child Growth Standards
Released new growth standards April 2006 Assumed that infants and children
between birth and 5 years grow similarly when needs are met.
Concerns for CDC charts included: Frequency of growth measures during
dynamic periods of infant growth Statistical methods
WHO growth charts
Data from Brazil, Ghana, India, Norway, Oman and USA
Multiethnic, affluent Exclusive breastfeeding to 4 months Solids according to recommendations
6 months Continued breastfeeding to 12 months
WHO growth charts
Full term low birthweight infants not excluded
Birth to 2 years N 1743 ----- 882
2-5 years N 6669
WHO v.s. CDC
Infancy WHO mean > CDC mean birth-6
months “healthy breastfed infants track
weight/age along WHO but falter on CDC”
Cross at 6 months and WHO mean < 6months
WHO v.s. CDC CDC
Heavier, shorter WHO
taller WHO
Higher estimates of overweight Lower estimates of underweight,
undernutrition
Gastrointestinal Maturation
Reference Josef Neu, Gastrointestinal Maturation and
implications for infant feeding, Early Human Development 2007 83 (767-775)
Neonatal Gastroenterology, Clinics in Perinatology June 1996 23:2
Weaver and Lucas Development of Gastrointestinal Structure and Function, Chapter 3 in Neonatal Nutrition and Metabolism ed Hay Mosby 1991
Nutrition and Metabolism of the Micropremie in Clinics in Perinatology March 2000n 27:1
Gastrointestinal Maturation
Intestinal length increase 1000X from 5-40 weeks, doubles in the last 15 weeks.
Villi formed at 16 weeks Fetus begins to swallow around 16
weeks by 2nd trimester is swallowing as frequently as every 45 minutes. By term, the fetus ingests approximately 300 ml/d
Maternal-fetal-placenta Interaction Individual metabolism
Glucose, amino acids, and fatty acids primary nutrients for tissue deposition and oxidative fuel
Hormonal regulation Not well understood Main hormones are placentally produced Insulin like growth factors induce cell proliferation and DNA,
increase glucose and amino acid uptake, and inhibit protein breakdown
Placental growth hormone stimulates IGF and is reduced in IUGR ? Leptin. Associated with fetal weight, fetal BMI, and fetal
fat mass
Carbohydrate Metabolism
Fetus Glucose and lactate
Glucose from maternal circulation via facilitated diffusion At birth, plasma glucose concentration about 2/3 maternal Used for oxidative fuel and source of carbon for glycogen
and other organic compounds Understress fetus can produce glucose with gluconeogenic
enzymes present at 10 weeks (but primarily maintained by maternal supply
hi
CHO
Term Infants: Lactase 30% of adult. Stimulated with
first feeds Preterm infants:
Lactase levels remain low <36 weeks 30-40% NB levels Breath hydrogen tests confirm
inefficient digestion of lactose
CHO
At birth Catoecholamines, thyroxin, and
glucagon increase and falling glucose levels stimulate glu-6-phosphatase
Glycogenolysis and hepatic glucose output are thus stimulated
CHO: Term Infant
Enzyme origin substrate Activity in newborn
amylase Salivary glandsPancreasHuman milk
Starch/glucose polymers
ModerateAbsent<6moshigh
Glucoamylase Intestine Glucose polymers
high
Sucrase-isomaltase
Intestine High
Lactase Intestine Lactose high
GI development Weeks GA
Esophagus Superficial glandsSquamous cells
2028
Stomach Gastric glandsPylorus and fundus defined
1414
Small intestine Crypt and villusLymph nodesPeptides and hormonesNeurotransmittersMyenteric plexus
1414141214
Colon Diameter decreasesVilli disappear
2020
Pancreas Differentiation of exocrine and endocrine tissue
14
Liver Lobule formation 11
Protein
Source of amino acids for protein synthesis
Release of bioactive peptides that contribute to regulation of many physiologic functions including metabolism, immunity, bllod pressure, GI function, and food intake
Protein Metabolism
Fetus requires protein for protein synthesis and the provision of energy
Maternal-fetal amino acid transfer is a complex process involving several sodium dependent transfer proteins. Intracellular and extracellular sodium gradient provides driving force
Fetal amino acid profile differs from neonate
Protein
Digested in upper intestine via pancreatic proteases. Most of the brush border and cytosolic peptidases are well developed in the preterm infant and peptide transport system is efficient.
Macromolucules can be actively taken up by pinocytosis and preterm infants have demonstrated to capability to absorb lactoferrin. Preterm infants have increased intestinal permeability
Lipid Metabolism
Fetus Fetus requires large amounts of lipids
particularly within developing nervous system (DHA, ARA)
Fetus acquires lipid via maternal placental transfer and capable of synthesizing cholesterol and fatty acids
Transfer impacted by maternal FA profile Dependent on maternal supply for EFA
Preterm
Bile acids and lipases limited Approx 30% newborn levels 24-36
weeks
Lipid:Term
Lipase Cofactors Substrate Contribution to fat digestion
Gastric lipase None TG Moderate to high
Pancreas Colipase and bile salts
TG low
Carboxylesterlipase
Bile salts TG Unknown to high
Pancreatic lipase
Phospholipids and TG
unknown
Milk bile salt dependent lipase
Bile salts TG Moderate to high
Development of Infant Feeding Skills Birth
tongue is disproportionately large in comparison with the lower jaw: fills the oral cavity
lower jaw is moved back relative to the upper jaw, which protrudes over the lower by approximately 2 mm.
tongue tip lies between the upper and lower jaws.
"fat pad" in each of the cheeks: serves as prop for the muscles in the cheek, maintaining rigidity of the cheeks during suckling.
feeding pattern described as “suckling”
Developmental Changes Oral cavity enlarges and tongue fills up less Tongue grows differentially at the tip and
attains motility in the larger oral cavity. Elongated tongue can be protruded to receive
and pass solids between the gum pads and erupting teeth for mastication.
Mature feeding is characterized by separate
movements of the lip, tongue, and gum pads or teeth
Development Neurophysiologic
Homeostasis Attachment Separation and
individuation Oral Motor
Stages of Development
Homeostasis Attachment Separation and individuation
StagesAge Development
1-3 months
Homeostasis * State regulation* Neurophysiologic stability
2-6 months
Attachment * “falling in love”* Affective engagement and interaction
6-36 months
Separation and individuation
* Differentiation* Behavioral organization and control
Feeding behavior of infants Gessell A, Ilg FL
Age Reflexes Oral, Fine, Gross Motor Development1-3months
Rooting and suckand swallowreflexes arepresent at birth
Head control is poorSecures milk with suckling pattern, the tongue projectingduring a swallowBy the end of the third month, head control is developed
4-6months
Rooting reflexfadesBite reflex fades
Changes from a suckling pattern to a mature suck withliquidsSucking strength increasesMunching pattern beginsGrasps with a palmer graspGrasps, brings objects to mouth and bites them
7-9months
Gag reflex is lessstrong as chewingof solids beginsand normal gag isdevelopingChoking reflexcan be inhibited
Munching movements begin when solid foods are eatenRotary chewing beginsSits aloneHas power of voluntary release and resecuralHolds bottle aloneDevelops an inferior pincer grasp
10-12months
Bites nipples, spoons, and crunchy foodsGrasps bottle and foods and brings them to the mouthCan drink from a cup that is heldTongue is used to lick food morsels off the lower lipFinger feeds with a refined pincer grasp
How?
Establish healthy feeding relationship Recognize child’s developmental abilities Balance child’s need for assistance with
encouragement of self feeding Allow the child to initiate and guide
feeding interactions Respond early and appropriately to
hunger and satiety cues
Analytical framework for the Start Healthy Guidelines for Complementary foods (JADA, 2004)
Baby Zoe
At BirthMaternal-Infant
DyadBreastfeeding Who does what?ExpectationsSubsequent feeding
practices?