Mbp growth 201112_28092011

Growth

HKU MBBS Year 3Patient Care Project (Mother-Baby) Presentation

Groups 8b – 11 UGLT 2, QMH

8, October, 20111

UNIVERSITY OF HONG KONGLI KA SHING FACULTY OF MEDICINE

Part 1Overview of Infant Growth

Ivan Wong, Philip Lee, Denise So, Jennie Yick, Bernard Shum


Part 1. Overview of Infant Growth

• Definition of growth• Phases of growth• Factors affecting growth• Allometric growth• Measurement of growth• Abnormal growth

– Failure to thrive– Overweight

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Growth

• Growth: increase in the size of the body• Development: increase in function of

processes related to body and mind

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• Fetal• Infantile • Childhood• Pubertal

5Phases of growth

Factors affecting growth

• Prenatal– Maternal factors (e.g. size of mother, maternal weight, BMI, toxic

exposure, nutritional state, hemodynamic status and stress)– Placental factors (e.g. size, microstructure, nutrient supply)– Fetal factors (e.g. genetics, nutrient and hormone production)

• Postnatal– Genetics (maternal and paternal)– Nutritional factors– Hormonal functions (e.g. thyroid, growth hormone)– Prenatal condition– Physical health (e.g. chronic illness)– Mental health (e.g. profound chronic unhappiness GH secretion↓)– Socioeconomic factors

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• Many organs/parts show disproportionate growth– at birth the head is about 25% of the body's length– but at maturity it is about 12% (or less) of its length

• The genetic basis of allometric growth involves differential timing of genes; therefore, it is a form of heterochrony

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Allometric growth

• Indicators:– Length/height– Weight– Body mass index– Head circumference– Arm circumference– Subscapular skinfold– Triceps skinfold– Motor development milestones

8The WHO child growth standards(http://www.who.int/childgrowth/standards/)

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Must be performed on a naked infant or a child dressed only in underclothing

Occipitofrontal circumference is a measure of head and hence brain growth. The maximum of 3 measurements is used

Correct technique matters

10 Correct technique matters

Growth charts

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Growth parameters should be plotted on charts

Q. Will the standards be applicable to all children?

A. The standards describe normal child growth under optimal environmental conditions and can be applied to all children everywhere, regardless of ethnicity, socioeconomic status and type of feeding.

(http://www.who.int/childgrowth/standards/)

Interpretation of growth charts

• A single growth parameter should not be assessed in isolation from the other growth parameters

• A single observation is difficult to interpret unless there is marked discrepancy– The further the parameter lies from the mean, the more likely it is

pathological

• Serial measurements are used to show the pattern and determine the rate of growth

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Examples of abnormal growth (1)

Failure to thrive • a description (not a diagnosis) applied

to children whose current weight or rate of weight gain is significantly below that of other children of similar age and sex

• Causes:– Organic (<5%)

• Accompanied by abnormal symptoms or signs

– Non-organic (>95%), e.g.• Inadequate availability of food• Psychosocial deprivation• Neglect or child abuse

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Failure to thrive • Investigations

– Most affected infants and toddlers do not require any investigations

• Management– Multidisciplinary

• Paediatric dietician• Clinical psychologist• Social worker• Nursery

– Carried out in primary care– Increasing energy intake by dietary and

behavioral modification and monitoring growth

– Hospital admission is usually only for severe cases

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Obesity• Obesity in children and

adolescents is defined as a BMI greater than the 95th percentile

• Increasing major health issue• Predisposing children to a wide

range of medical and psychological problems in childhood and adult life– Especially type 2 diabetes mellitus

and cardiovascular disease


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Obesity• Management

– Sustained changes in lifestyle, e.g. healthier eating, increased physical activity, and reduction in physical inactivity difficult to achieve and even harder to maintain

– Cultural change in our society should be considered, e.g. removal of ‘tuck shops’ and vending machines with unhealthy food and drinks from schools

– Drug treatment and surgical intervention are only appropriate in a small number of children

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Part 2 – Statistics from PCP-MB

Our Aim:

• Determine whether the growth of infants in HK is influenced by the following factors1. Mode of feeding2. Mode of delivery3. Gestational age at delivery

Why we chose these aspects for analysis:

• we chose these topics because:– 1. we believe feeding method and feeding as a

whole will have major influence on postnatal growth

– 2. Medicalization of pregnancy has led to change in the trend of method of delivery which may impact growth

– 3. Assisted delivery method may influence the age of infants at delivery which can later affect postnatal growth

Summary of the data sample

Part 2.1 Does Breast Feeding affect the initial growth rate of newborns?

Cherlyle Chan, Jason Law, LEUNG Yuen Yee, LUI Shing Tsun, Arthur Mak, PUK Kam Yan , Salvio Ng, Amanda Slocum, Jeffrey Tsang


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Literature review

Fulhan J et al: Update on pediatric nutrition: Breastfeeding, infant nutrition, and growth. Curr Opin Pediatr. 2003 Jun;15(3):323-32.

• Protein– Adequate for growth

• Vitamins A and B6– Highly dependent on maternal stores– Sufficient in well-nourished populations

• Vitamin D– Small amount in breast milk– Depend on exogenous sources of vitamin D or sunlight for

bone health

Literature review

Fulhan J et al: Update on pediatric nutrition: Breastfeeding, infant nutrition, and growth. Curr Opin Pediatr. 2003 Jun;15(3):323-32.

• Calcium– Independent of mother’s diet– Fairly constant throughout lactation

• Iron and Zinc– Dependent on:

• Endogenous stores of infants• Amount received through diet

– Iron must be received from complementary foods or additional supplements after stores diminish (after 6 months)

– Level of maternal zinc stores is important

Literature reviewLiterature review

Literature review

Anderson AK: Association between Infant Feeding and Early Postpartum Infant Body Composition: A Pilot Prospective Study. Int J Pediatr. 2009;2009:648091. Epub 2009 Mar 12.

• Aim: To compare the weight gain of infants in the early postpartum period (first 12 weeks of delivery) between newborns who were exclusively breastfed and those who were given mixed feeding

• Results: Rate of both weight gain and adiposity was a little bit higher among infants who were exclusively breastfed as compared to those who received mixed feeding

• Consistent with previous studies which compared exclusive breastfeeding with formula feeding

• Follow-up: further examine the change in percentage body fat at 6 months and 12 months postpartum

Literature review

Kramer MS et al: Breastfeeding and Infant Growth: Biology or Bias?. Pediatrics. 2002 Aug;110(2 Pt 1):343-7.

• Aim: To compare between the breastfeeding promotion intervention (modeled on the WHO/UNICEF Baby-Friendly Hospital Initiative) and the control infant feeding practices

• Compared infants who were weaned in the first month with those who were breastfed for the full 12 months with either at least 3 months or at least 6 months of exclusive breastfeeding

• Results: Mean birth weight was significantly higher in the experimental group by 1 month of age. Difference in weight gain increased through the 3 months but declined slowly thereafter before disappearing by 12 months

• This suggests that prolonged and exclusive breastfeeding has the potential in accelerating weight and length gain in the first few months without any detectable deficit by 12 months of age.

Data AnalysisData Analysis

Implications:

Growth rate of breast-fed female babies is higher than that of formula-fed.

There is significant evidence in the beneficial effects of breast feeding over formula feeding on growth in female babies.

The weight of FEMALE babies against age

Breast-fed female babies (blue) VSFormula-fed female babies (red)

Data Analysis

Data Analysis

The weight of MALE babies against age

Implications:

The growth rate of breast-fed male babies is similar to that of formula-fed.

There is no significant evidence of the beneficial effects of breast feeding on growth in male babies.

Breast-fed male babies (blue) VSFormula-fed male babies (red)

Part 2.2 Does the mode of delivery affect the initial growth rate of

newborns?Keedon Wong, Becky Ma, Jonathan Chow, Ponie Lee, Kathy Lam, Ling

Kong, Staccato Lau, Andrew Mak, Lee Kit Ming


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Literature review

Literature Review

Planned cesarean versus planned vaginal delivery at term: Comparison of newborn infant outcomes1

Kolas et. al (2005) American Journal of Obstetrics and Gynecology

There were no significant differences in the risks for low Apgar score and neurologic symptoms.

Planned vaginal delivery versus elective caesarean section in singleton term breech presentation: a study of 1116 cases2 . Golfier et. al (2001). European Journal of Obstetrics & Gynecology and Reproductive Biology

C-section is better for infant health but worse for maternal health in breech presentation.

Mode of Delivery and Asthma - Is There a Connection? 3 Kero et. al (2002) Pediatric Research

The register study showed the cumulative incidence of asthma at the age of seven to be significantly higher in children born by caesarean section (4.2%) than in those vaginally delivered (3.3%),

Methodology

Pool of Data

Assisted Vaginal Delivery

Natural Vaginal Delivery

Caesarean Delivery

Assisted Vaginal Delivery

Natural Vaginal Delivery

Growth rate of:• Head

circumference

• Body Length• Body Weight


circumference


Caesarean Delivery


circumference


Any Statistical Differences?

Any Statistical Differences?

Methodology

Growth Rate (GR)

Head Circumference DAY 0 – Head Circumference DAY 10

Gestational Weeks in between (2)

Variable DAY 0 – Variable NEXT EARLIEST DAY WITH DATA

Duration in between (Gestational Weeks)

Example

Results

t-test for equality of Means between ‘Assisted’ & ‘Natural Vaginal Delivery’

Difference in GR of Body Weight; p=0.585

Difference in GR of Body Length; p=0.248

Difference in GR of Head Circumference; p=0.558

t-test for equality of Means between ‘Caesarean’ & ‘Natural Vaginal Delivery’

Difference in GR of Body Weight; p=0.877

Difference in GR of Body Length; p=0.155

Difference in GR of Head Circumference; p=0.730

GR of Body WeightMode of Delivery

n Mean S.D.

Assisted 7 0.227 0.120

Natural 28 0.199 0.123

Caesarean 18 0.193 0.121

Mode of Delivery

n Mean S.D.

Assisted 6 0.752 0.417

Natural 18 0.516 0.425

Caesarean 17 0.747 0.526

GR of Body Length

GR of Head CircumferenceMode of Delivery

n Mean S.D.

Assisted 4 0.516 0.164

Natural 15 0.199 0.123

Caesarean 18 0.193 0.120

Statistically Insignificant

Discussion

This is a pilot study with no other research data on the same set of parameters.

7 studies further reviewed: compared the outcomes of vaginal delivery and cesarean section by: 1. infant health, e.g. mortality rate, risk of

respiratory morbidity 1-4, 2. birth weight5-6, 3. and growth-related hormone measurements7. None of these studies show directrelationship between modes ofdelivery and growth.

New Questions

Are there any confounding factors?

Perhaps the parameters (head circumference/body weight/body length) might not be sensitive enough to document growth rate in this study?

Equation for growth rate might not capture the real growth rate accurately?

Future Study

How does the mode of delivery affect growth hormones levels in newborns?

Variability in the duration between data points used to measure GR

Low sample size

Assumed linear growth of infant

Reporting & selection bias

Limitations

Literature

Part 2.3 Does the gestational age at delivery affect the initial growth rate of

newborns?Simon Chan, Tom Chow, Bernice Yu, Denise Cheng, Derek Ng, Eric Ng,

Simon Yan, Cyrus Lai, Herriet Tsang


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Literature review

• Growth of preterm infants• Catch-up growth

• Gairdner, D., and Pearson, J. (1971)

• 4 phases of growth usually observed:

Phase 1: immediate postnatal weight loss.

Phase 2: (half to 1week) Rate of growth is similar to that of the foetus of comparable gestational age.

Phase 3: growth rate accelerates, much exceeds that of the foetus.

Phase 4: continue in the same percentile.

Literature Review

Insufficient early weight gain in preterm babies andinfluence on weight at 12 monthsDavies D P and Kennedy J D, (1981)

• 30 preterm white infants of AGA weight born <32 complete weeks of gestation were studied

• No significant correlations to suggest that insufficient early weight gain affected later patterns of weight.

Is term newborn body composition being achieved postnatally in preterm infants?Roggero et al (2009)

• Preterm infants <30weeks gestation studied

• Weight, length and head circumference were smaller in the preterm group (no catch-up evident)

Literature: Phase 3 – Catch-up phase?

Assessment of Gestational Age

Estimation from last menstrual period(LMP)• Naegele’s rule : Add seven days and subtract three

months from the LMP

Advantage Disadvantage•Easy, Quick •Difficulty of determining the

LMP

•Inaccurate GA for mothers having variable cycles or conceives while taking contraceptive

Assessment of Gestational Age (2)

Prenatal Ultrasonography• Before visualization of the embryo 30 + Gestational sac diameter (mm) = Gestational day

• After visualization - Crown – rump length - Biparietal diameter, Head circumference, Femur length, Abdominal circumference

Assessment of Gestational Age (3)

New Ballard Score• Determine GA through Neuromuscular and

Physical assessment of a newborn• Physical parameters: Skin, Lanugo, Plantar

surface, Breast, Eye/Ear, Genitals (M/F)• Neuromuscular parameters: Posture, Square

window, Arm recoil, Popliteal angle, Scarf sign, Heel to ear

……… In 530 infants, gestational age by last menstrual period was confirmed by agreement within 2 weeks with gestational age by prenatal ultrasonography (C-GLMP). For these infants, correlation between gestational age by NBS and C-GLMP was 0.97. Mean differences between gestational age by NBS and C-GLMP were 0.32 +/- 1.58 weeks and 0.15 +/- 1.46 weeks among the extremely premature infants (less than 26 weeks) and among the total population, respectively. ………

Any duplication in data entry has been removed

Gestational age has been corrected to nearest week

The term of delivery has been defined (*see next slide)

Age measurement has been corrected to duration since birth in weeks

Rate of growth has been calculated as follow:• Rate of weight gain = (first weight measured – weight at birth)/age at

measurement in weeks• Rate of height gain = (first height measured - height at birth)/age at

measurement in weeks• Rate of head circumference gain = (first head measured – head at birth)/age

at measurement in weeks

Entries with missing data are excluded in analysis.

Data processing

Definition of Preterm Birth

From WHO:• Defined as childbirth occurring at less than 37

completed weeks or 259 days of gestation• Major determinant of neonatal mortality and

morbidity• Has long-term adverse consequences for

health

Assumptions in data analysis

The sample of infants and mothers recruited in PCP-MB project has been random, and is representative of the HK population at large.

The gestational age has not been pre-rounded during data entry. Thus data cleaning process has not introduced bias.

The growth during the initial post-natal period has been linear or near-linear such that rate of growth calculated is a comparable variable.

Genetic factors, calories intake, living environment or health issues are the same for all infants

Nutritional contents are the same between breast-milk and different brands of formula.

Is growth rate associated with gestational age at birth?

Conclusion: The lines of best fit shows that in general, there is a positive linear correlation between gestational age at delivery and rate of postnatal growth. However, R2 shows that the strength of association is (very) weak.

Closer look at such correlation

• The table shows that the correlation between the three growth rate parameters with gestational age at birth are all statistically non-significant. Thus the small positive correlation may be spurious.

This part of the table shows that the three parameters have significant and strong correlation with each other. Reflecting that there are agreement in these measurements.

Conclusion• This shows that the

rate of gain in weight, length, and head circumference are similar between preterm and full term infants.

Even if there is no association, do preemies grow quicker? (catch up growth)

Conclusion• The difference in rate

of gain in weight, length, head circumference are not significant

• For males, the rate of growth for full term and preterm infants are similar.

• For female however , there appears to be significant difference.– Significant since

the 95% CI do not overlap

• This is strange !?

Looking deeper into catch up growth

Explanation• Since there is only 1 preterm

female in the sample group• Variance cannot be estimated

(therefore not drawn on the graph) and has to be assumed equal in T test.

• T test shows that there is no significant difference between female premies and full-tern infants rate of growth

Summary of results

• Data analysis shows that there is no significant association between gestational age of delivery and postnatal rate of growth.

• Data shows that there is no significant difference in rate of growth between preterm and full term infants. -- No catchup growth observed.

Discussion & Limitations

Disccusion1. It is contra-intuitive

1. growth rate is higher in infants born at higher gestational age.

2. Despite the correlation being very weak and statistically insignificant.

2. Phase 3 - Catch up growth was not demonstrated.

1. due to our growth rate estimates only reflecting the initial rate of growth during the earliest post-natal period.

2. These estimates may be reflecting phase 2 growth so the significant acceleration has not been captured by the data.

Limitations• Although significant difference in

rate of growth was not apparent between full and pre-term, this may be due to:– Insufficient sample size, not

enough preterm infants (particularly female), no extreme of preterm.

– Growth recording was not implemented stringently.

– Our assumptions that genetic factors, calories intake, living environment or health issues are the same for all infants may not be true.

Part 3Conclusion & improvement

Overall


1.) Breast Feeding2.) Gestational age3.) Mode of delivery

Conclusion

No Significant Correlation between growth rate

Why?!

• Due to 1.) Small Sample size (<70 participants) 2.) Reporting Bias (too many missing data)

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Conclusion

~Further Improvement of the research1.) Using Data along with previous year PCP-MB to compare to increase sample size or to compare2.) Trying hard to ask every pair of PCP-MB to gather as many relevant information as much as possible

Reference (1)

1. Golfier F, Vaudoyer F, Ecochard R, et al: Planned vaginal delivery versus elective caesarean section in singleton term breech presentation: a study of 1116 cases. Eur J Obstet Gynecol Reprod Biol. 2001;98:186-92.

2. Kero J, Gissler M, Gronlund MM, et al: Mode of delivery and asthma -- is there a connection? Pediatr Res. 2002;52:6-11.

3. Kolas T, Saugstad OD, Daltveit AK, et al: Planned cesarean versus planned vaginal delivery at term: comparison of newborn infant outcomes. Am J Obstet Gynecol. 2006;195:1538-43.

4. Morrison JJ, Rennie JM,Milton PJ: Neonatal respiratory morbidity and mode of delivery at term: influence of timing of elective caesarean section. Br J Obstet Gynaecol. 1995;102:101-6.

5. Lee KS, Khoshnood B, Sriram S, et al: Relationship of cesarean delivery to lower birth weight-specific neonatal mortality in singleton breech infants in the United States. Obstet Gynecol. 1998;92:769-74.

6. Naylor CD, Sermer M, Chen E, et al: Cesarean delivery in relation to birth weight and gestational glucose tolerance: pathophysiology or practice style? Toronto Trihospital Gestational Diabetes Investigators. Jama. 1996;275:1165-70.

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Reference (2)

7. Bird JA, Spencer JA, Mould T, et al: Endocrine and metabolic adaptation following caesarean section or vaginal delivery. Arch Dis Child Fetal Neonatal Ed. 1996;74:F132-4.

8. J Cockerill, S Uthaya, C J Doré, and N Modi: Accelerated postnatal head growth follows preterm birth.Arch Dis Child Fetal Neonatal Ed. 2006 May;91(3):F184-7. Epub 2006 Jan 12.

9. Luciana Friedrich, Paulo M. C. Pitrez, Renato T. Stein, Marcelo Goldani, Robert Tepper, and Marcus H. Jones: Growth Rate of Lung Function in Healthy Preterm Infants. Am J Respir Crit Care Med. 2007 Dec 15;176(12):1269-73. Epub 2007 Sep 20.

10. Paola Roggero , Maria Lorella Giannì, Orsola Amato et al: Is term newborn body composition being achieved postnatally in preterm infants? Early Hum Dev. 2009 Jun;85(6):349-52. Epub 2009 Jan 21.

11. Gairdner, D., and Pearson, J.: A Growth Chart for Premature and other Infants. Arch Dis Child. 1971 Dec;46(250):783-7.

12. Davies D P and Kennedy J D: Insufficient early weight gain in preterm babies and influence on weight at 12 months. Arch Dis Child. 1986 Jan;61(1):96

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