Fenton and Kim BMC Pediatrics 2013, 13:59
http://www.biomedcentral.com/1471-2431/13/59

TECHNICAL ADVANCE

Open Access

A systematic review and meta-analysis to revise
the Fenton growth chart for preterm infants
Tanis R Fenton1,2* and Jae H Kim3

Abstract
Background: The aim of this study was to revise the 2003 Fenton Preterm Growth Chart, specifically to: a)harmonize the preterm growth chart with the new World Health Organization (WHO) Growth Standard, b) smooththe data between the preterm and WHO estimates, informed by the Preterm Multicentre Growth (PreM Growth)
study while maintaining data integrity from 22 to 36 and at 50 weeks, and to c) re-scale the chart x-axis to actualage (rather than completed weeks) to support growth monitoring.
Methods: Systematic review, meta-analysis, and growth chart development. We systematically searchedpublished and unpublished literature to find population-based preterm size at birth measurement (weight,
length, and/or head circumference) references, from developed countries with: Corrected gestational ages
through infant assessment and/or statistical correction; Data percentiles as low as 24 weeks gestational age or
lower; Sample with greater than 500 infants less than 30 weeks. Growth curves for males and females were
produced using cubic splines to 50 weeks post menstrual age. LMS parameters (skew, median, and standard
deviation) were calculated.
Results: Six large population-based surveys of size at preterm birth representing 3,986,456 births (34,639 births< 30 weeks) from countries Germany, United States, Italy, Australia, Scotland, and Canada were combined inmeta-analyses. Smooth growth chart curves were developed, while ensuring close agreement with the data between
24 and 36 weeks and at 50 weeks.
Conclusions: The revised sex-specific actual-age growth charts are based on the recommended growth goal forpreterm infants, the fetus, followed by the term infant. These preterm growth charts, with the disjunction between
these datasets smoothing informed by the international PreM Growth study, may support an improved transition ofpreterm infant growth monitoring to the WHO growth charts.
Keywords: Infant, Premature, Infant, very low birth weight, Preterm infant, Growth, Weight, Head circumference,
Length, Percentile

BackgroundThe expected growth of the fetus describes the fastest
human growth, increasing weight over six-fold between
22 and 40 weeks. Preterm infants, who are born during
this rapid growth phase, rely on health professionals toassess their growth and provide appropriate nutrition
and medical care.

* Correspondence: tfenton@ucalgary.ca
1
Alberta Children’s Hospital Research Institute, The University of Calgary,
Calgary, AB, Canada
2
Department of Community Health Sciences, The University of Calgary, 3280
Hospital Drive NW, Calgary, AB, Canada
Full list of author information is available at the end of the article

In 2006, the World Health Organization (WHO)published their multicentre growth reference study, whichis considered superior [1] to previous growth surveys since
the measured infants were selected from communities inwhich economics were not likely to limit growth, amongculturally diverse non-smoking mothers who planned tobreastfeed [2]. Weekly longitudinal measures of the infants
were made by trained data collection teams during the first
2 years of this study [3]. These WHO growth charts,
although recommended for preterm infants after term age[4], begin at term and so do not inform preterm infant
growth assessments younger than this age.

© 2013 Fenton and Kim; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of theCreative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.

Fenton and Kim BMC Pediatrics 2013, 13:59
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Optimum growth of preterm infants is considered to beequivalent to intrauterine rates [5-7] since a superior
growth standard has not been defined. Perhaps the best
estimate of fetal growth may be obtained from large
population-based studies, conducted in developed countries [8], where constraints on fetal growth may be lessfrequent.
A recent multicentre study by our group (the Preterm
Multicentre Growth (PreM Growth) Study) revealed that
although the pattern of preterm infant growth was generally consistent with intrauterine growth, the biggest deviation in weight gain velocity between the preterm infants
and the fetus and infant was just before term, between 37
and 40 weeks (Fenton TR, Nasser R, Eliasziw M, Kim JH,
Bilan D, Sauve R: Validating the weight gain of preterm infants between the reference growth curve of the fetus andthe term infant, The Preterm Infant Multicentre Growth
Study. Submitted BMC Ped 2012). Rather than demonstrating the slowing growth velocity of the term infantduring the weeks just before term, the preterm infants hadsuperior, close to linear, growth at this age. This finding
has been observed by others as well [9-11]. Therefore,
there is evidence to support a smooth transition on
growth charts between late fetal and early infant ages.
Several previous growth charts based on size at birthpresented their data as completed age, which affects theinterpretation and use of a growth chart [12]. The use ofcompleted weeks when plotting a growth chart requires
all the measurements to be plotted on the whole week
vertical axes. However, the use of completed weeks in aneonatal unit may not be intuitive, as nursery staff andparents think of infants as their exact age, and not age
truncated to previous whole weeks. The advent ofcomputers in health care, for clinical care and healthrecording, allow the use of the computer to plot growth
charts, daily and with accuracy. It would make sense tosupport plotting daily measurements continuously byshifting the data collected as completed weeks to the
midpoint of the next week to remove the truncation of
the data collection as completed weeks.
The objectives of this study were to revise the 2003
Fenton Preterm Growth Chart, specifically to: a) use more
recent data on size at birth based on an inclusion criteria,b) harmonize the preterm growth chart with the new
WHO Growth Standard, c) to smooth the data between
the preterm and WHO estimates while maintaining
integrity with the data from 22 to 36 and at 50 weeks,d) to derive sex specific growth curves, and to e) re-scale
the chart x-axis to actual age rather than completed
weeks, to support growth monitoring.

Methods
To revise the growth chart, thorough literature searches
were performed to find published and unpublished

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population-based preterm size at birth (weight, length,
and/or head circumference) references. The inclusion
criteria, defined a priori, designed to minimize bias byrestriction [13], were to locate population-based studies
of preterm fetal growth, from developed countries with:a) Corrected gestational ages through fetal ultrasoundand/or infant assessment and/or statisticalcorrection;b) Data percentiles at 24 weeks gestational age or
lower;c) Sample of at least 25,000 babies, with more than 500
infants aged less than 30 weeks;d) Separate data on females and males;e) Data available numerically in published form orfrom authors,f ) Data collected within the past 25 years (1987 to 2012)
to account for any secular trends.
A. Data selection and combination

Major bibliographic databases were searched: MEDLINE(using PubMed) and CINHAL, by both authors back toyear 1987 (given our 25 year limit), with no language
restrictions, and foreign articles were translated. The
following search terms as medical subject headings andtextwords were used: (“Preterm infant” OR “Premature
Birth”[Mesh]) OR (“Infant, Premature/classification”[Mesh]
OR “Infant, Premature/growth and development”[Mesh]
OR “Infant, Premature/statistics and numerical data”[Mesh]
OR “Infant, very low birth weight”[Mesh]) AND(percentile OR *centile* OR weeks) AND (weight OR headcircumference OR length). Grey literature sites including
clinical trial websites and Google were searched in February
2012. Reference lists were reviewed for relevant studies.
All of the found data was reported as completed weeks
except for the German Perinatal Statistics, which werereported as actual daily weights [14]. To combine thedatasets, the German data was temporarily converted tocompleted weeks. A final step converted the meta-analyses
to actual age.
B. Combine the data to produce weighted intrauterine
growth curves for each sex

The located data (3rd, 10th, 50th, 90th, and 97th percentiles
for weight, head circumference, and length) that met theinclusion criteria were extracted by copying and pasting
into spreadsheets. The male and female percentile
curves from each included data set for weight, headcircumference and length were plotted together so they
could be examined visually for heterogeneity (Figures 1, 2,
and 3). The data for each gender were combined by using
the weekly data for the percentiles: 3rd, 10th, 50th, 90th,
and 97th, weighted by the sample sizes. The combined
data was represented by relatively smooth curves.

Fenton and Kim BMC Pediatrics 2013, 13:59
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Figure 1 Boys birthweight centiles (3rd, 50th and 97th) fromthe six included studies, along with the boy’s meta-analysis
curves (bold).

C. Develop growth monitoring curves

To develop the growth monitoring curves that joined
the intrauterine meta-analysis data with the WHO
Growth Standard (WHOGS) smoothly, the following
cubic spline procedure was used to meet two objectives:

Figure 2 Girls head circumference centiles (3rd, 50th and 97th)
centiles from the included studies, along with the girl’smeta-analysis curves (dotted), and after 40 weeks, the World
Health Organization centiles (dashed).

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Figure 3 Girls length centiles (3rd, 50th and 97th) centiles fromthe included studies, along with the meta-analysis curves(dotted), and after 40 weeks, the World Health Organization
centiles (dashed).

a) To maintain integrity with the meta-analysis curves
from 22 to 36 weeks. Integrity of the fit was
assumed to be agreement within 3% at each week.
b) To ensure fit of the data to the WHO values at 50
weeks, within 0.5%.
Procedure:
1) Cubic splines were used to interpolate smoothvalues between selected points (22, 25, 28, 32, 34, 36
and 50 weeks). Extra points were manually selected
at 40, 43 and 46 weeks in order to produce
acceptable fit through the underlying data. The
PreM Growth study (Fenton TR, Nasser R, Eliasziw
M, Kim JH, Bilan D, Sauve R: Validating the weightgain of preterm infants between the reference
growth curve of the fetus and the term infant, The
Preterm Infant Multicentre Growth Study.
Submitted BMC Ped 2012) conducted to inform thetransition between the preterm and WHO data, wasused to inform this step. The Prem Growth Study
found that preterm infants growth in weight
followed approximately a straight line between 37
and 45 weeks, as others have also noted [9-11].
2) LMS values (measures of skew, the median, and thestandard deviation) [15] were computed from theinterpolated cubic splines at weekly intervals. Cole’s
procedures [15] and an iterative least squares method
were used to derive the LMS parameters (L = Box-Cox
power, M = median, S = coefficient of variation) from

Data source

Voight, 2010

Olsen, 2010

Kramer, 2001

Roberts, 1999

German Perinatal
SurveyPediatrix Medical Grouphospitals

Canadian national file

Australian National
Scottish maternity data Italian Neonatal
Perinatal Statistics Unit collection
Study

Bonellie, 2008

Bertino, 2010

WHO, 2006
WHO multicentre growthreference study

Sample size

2,300,000

130,111676,605

734,145

100,133

45,462882

n < 30 weeks

14146

11377

3247

3193

2053

623

N/A

Lowest gestational
age

22

23

22

20

24

23

term

Dates

1995 to 2000

1998 to 2006

1994 to 1996

1991 to 1994

1998 to 2003

2005 to 2007

1997-2003

Data

WeightWeight, head, length

WeightWeightWeightWeight, head, length

Weight, head, length

Exclusion criteria

None stated,
included bothlive and stillborn

Multiple births, congenital
anomalies, death before
discharge, outlier measures(> 2 x interquartile range
below the first and3rd quartile).

Ontario province was
excluded due toproblems with data
quality.

Omitted multiple andstill births (births < 400grams did not need tobe recorded)

Multiple births, lethal
anomalies, weights< 250 grams, andoutlier measures(> 2 x interquartile
range outside the firstand 3rd quartile).

Multiple births, stillbirths,
major congenital
anomalies, and fetalhydropsMaternal smoking, notbreastfeeding, solids before
4 months. Screened forenvironmental or
economic constraints.

Method to assessgestational age

Neonatologist assessment
Ultrasoundassessment 8–14
weeks and Naegle’s
rule.

“early ultrasound has
increasingly been thebasis for gestational
age assessments inrecent years”

Dates, prenatal, or
postnatal assessment

Clinician assessment
based on ultrasound,maternal dates, andclinical estimates

Ultrasound assessment
first trimester

Not stated

Assumed a log normal
distribution of birthweightat each gestational age
and compared theprobabilities of accurate
versus misclassification of
infant’s gestational age

Omitted outlier
measures (> 2 x
interquartile range
below the first and3rd quartile).

Cubic spline fitting

Generalized logistic
functions

Omitted outliers > 3 SD,
LMS parameter smoothing,skew set to one for weight,
cubic spline fitting.

Outliers/smoothing Cubic regression, LMS methods, with themethodLOESS smoothing, skew set to one andfurther manual smoothing
LMS parametersmoothing

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Table 1 Details of the data sources

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Identification

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2436 records identified throughdatabase searching

153 duplicates identified

Screening(Medline & Grey literature)

63 records screened

Eligibility

12 additional records identified through othersources

69 full-text articles excluded:
Date of birth criteria (n=27)
Not developed country (n= 4)
Insufficient n (n=25)
Numerical data not available (n=5)
Not population based (n=3)
Uncorrected gestational ages (n=3)
No direct measurements (n=1)
Duplicate data (n=1)

Included

75 of full-text articles
assessed for eligibility

6 studies included inmeta-analysis

Figure 4 Flow diagram of studies identified, excluded and included in the systematic review.

Table 2 Number of infants each week from each study
Gestational age

Voight, 2010

Olsen, 2010

Bertino, 2010

Kramer, 2001

Roberts, 1999

Bonellie, 2008

Females

Males

Females

Males

Females

Males

Females

Males

Females

Males

Females

Males

22

188

321

-

-

-

-

80

82

71

74

-

-

23

431

560

133

153

3

8

106

114

79

95

-

-

24

575

704

438

451

20

24

148

156

115

135

120

126

25

713

846

603

722

40

38

184

202

136

180

115

118

26

812

968

773

881

35

58

191

234

188

235

179

172

27

1073

1203

966

1030

52

61

188

254

231

284

174

177

28

1276

1536

1187

1281

79

63

287

330

287

361

246

239

29

1516

1838

1254

1505

70

72

299

392

325

397

245

265

30

1853

2212

1606

1992

107

114

390

467

440

571

317

313

31

2283

2956

2044

2460

126

140

461

584

548

743

136

148

32

*

*

3007

3677

165

183

795

997

877

1117

193

205

33

*

*

4186

5014

211

240

1055

1368

1200

1471

239

256

34

*

*

5936

7291

263

349

2018

2553

2086

2657

374

422

35

*

*

5082

6952

366

418

3391

4314

3418

4092

644

653

36

*

*

4690

7011

562

665

8203

9648

7320

8788

1048

1265

37

*

*

4372

6692

1291

1492

17308

19965

16105

18660

2006

2499

38

*

*

5755

8786

3524

3976

47516

51947

47809

51404

4630

6387

39

*

*

5978

8324

5295

5452

75068

77623

68846

72871

8699

10706

40

*

*

5529

7235

5672

5653

110738112737137570141553

12644

14230

* Not reported.

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the multicentre meta-analyses for weight, headcircumference and length. The LMS splines weresmoothed slightly while maintaining data integrity as
noted above.
3) The final percentile curves were produced from thesmoothed LMS values.
4) A grid similar to the 2003 growth chart was used,
but the growth curves were re-scaled along thex-axis from completed weeks to allow clinicians toplot infant growth by actual age in weeks, and aslight modification (scaled to 60 centimeters insteadof 65) was made to the y-axis.
D. Compared the revised charts with the 2003 version

The revised growth charts were compared graphically withthe original 2003 Fenton preterm growth chart. To makethe differences in chart values more apparent, the 2003
chart data was also shifted to actual weeks for these comparison figures.

Results
Six large population based surveys [14,16-20] of size at
preterm birth from countries Germany, United States,
Italy, Australia, Scotland, and Canada were located that
met the inclusion criteria (Table 1). The literature search
identified 2436 papers, of which 2373 were discarded as
being not relevant or duplicates based on the titles(Figure 4). Reviewing reference lists identified another12 studies. Seventy-five studies were examined in detail,however 27 of these did not meet the date criteria. Amongthe 48 studies that met the date of birth criteria, some did
not meet the other inclusion criteria for the following
reasons: Did not meet the criterion for more than 25,000
babies [21-35], no low gestational age infants less than 25
weeks [31,36-41], insufficient number less than 30 weeks[34,42-45], no statistical correction for inaccurate
gestational ages [46-48], numerical data not available[49-51], number of infants each week were not available

Figure 5 Boys meta-analysis weight curves (dotted) with thefinal smoothed growth chart curves (dashed).

Figure 6 Boys meta-analysis head circumference curves(dotted) with the final smoothed growth chart curves (dashed).

[52], number of infants in the subgroups each week were
not available [53], was not population based [54-56], no
direct measurements [27], some of the data [57] was also
in one of the larger included studies [17].
Included in the meta-analyses were almost four million(3,986,456) infants at birth (34,639 less than 30 weeks)
from six studies for weight (Table 2), and 173,612 infants
for head circumference, and 151,527 for length [16,18].
The World Health Organization data measurements
were made longitudinally on 882 infants.
The individual datasets from the literature showed
good agreement with each other, especially along the50th and lower centiles (Figures 1, 2, and 3) and themeta-analysis curves had a close fit with the individual
datasets up to 36 weeks and at 50 weeks (Figures 5, 6, 7).
The final splined weight curves were within 3% of themeta-analysis curves for 24 through 36 weeks for both genders, except for a 3.8% difference for girls at 32 weeks alongthe 90th centile. None of the length measurements differedby more than 1.8% percent between the meta-analysis andthe splined curves; all weeks of the head circumference
curves were within 1.5%. The meta-analyses for head

Figure 7 Boys meta-analysis length curves (dotted) with thefinal smoothed growth chart curves (dashed).

Fenton and Kim BMC Pediatrics 2013, 13:59
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circumference and length for girls and boys were closeenough to normal distributions that normal distributions
were used to summarize the data. The measures at 50
weeks were within 0.5% of the WHOGS values.
Girl and boy charts were prepared (Figure 8 and 9), byshifting the age by 0.5 weeks to allow plotting by exact
age instead of completed weeks. The LMS Parameters[15] were used to develop the exact z-score and percentile
calculators for the new growth chart.
In the two graphical comparisons between the revised
growth charts, one for each sex, with the 2003 Fenton

Figure 8 Revised growth chart for girls.

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preterm growth chart revealed that the curves were quite
similar (Figures 10 and 11). Generally the new girls’ curves
were slightly lower (Figure 10) and the new boys’ slightly
higher (Figure 11) for all 3 parameters (weight, head circumference, and length) than the 2003 curves. The mostdramatic visual and numerical difference between the newcharts and the 2003 chart was the higher shift of the boys’
weight curves after 40 weeks compared to the 2003 chart,reaching a maximum difference at 50 weeks of 650, 580,
and 740 grams at the 3rd, 50th, and 97th percentiles, respectively. The second biggest visual difference was theFenton and Kim BMC Pediatrics 2013, 13:59
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Figure 9 Revised growth chart for boys.

lower pattern of the girls’ length curves below 37 weeks;
the difference in length reached a maximum numericalvalue of 1.7 centimeters at 24 weeks along the 97th
percentile.

Discussion
We used a strict set of inclusion criteria to include only
the best data available to convert fetal and infant size data
into fetal-infant growth charts for preterm infants. The revised sex-specific actual-age (versus completed weeks)
growth charts (Figure 9 and 10), are based on birth size information of almost four million births with confirmed orcorrected gestational ages, born in developed countries(See Features of the new growth chart). The revised charts
are based on the recommended growth goal for preterm
infants, the fetus and the term infant, with smoothing of
the disjunction between these datasets, based on the findings of our international multicentre validation study(Fenton TR, Nasser R, Eliasziw M, Kim JH, Bilan D, Sauve
R: Validating the weight gain of preterm infants between
the reference growth curve of the fetus and the term infant, The Preterm Infant Multicentre Growth Study.
Submitted BMC Ped 2012). These charts are consistent with the meta-analysis data up to and including

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Figure 10 Comparison of the revised growth chart for girls (solid curves) and the 2003 Fenton growth chart (dashed curves) 3rd, 50th,and 97th percentile curves for length, head circumference, and weight). Both the 2003 and the revised growth curves are shown shifted toactual weeks.

36 weeks, thus they can be used for the assessmentof size for gestational age for preterm infants under 37
weeks of gestational age. This growth chart is likely applicable to preterm infants in both developed and developing countries since the data was selected fromdeveloped countries to minimize the influence from circumstances that may not have been ideal to support
growth.
Features of the new growth chart Based on the recommended growth goal for preterm

infants: The fetus and the term infant Girl and boy specific charts
 Equivalent to the WHO growth charts at 50 weeks

gestational age (10 weeks post term age).
 Large preterm birth sample size of 4 million infants;
 Recent population based surveys collected between

1991 to 2007

 Data from developed countries including

Germany, Italy, United States, Australia, Scotland,
and Canada Curves are consistent with the data to 36 weeks,
thus can be used to assign size for gestational age up
to and including 36 weeks.
 Chart is designed to enable plotting as infants aremeasured, not as completed weeks. The x axis was
adjusted for this chart so that infant size data can beplotted without age adjustment, i.e. Babies should beplotted as exact ages, that is a baby at 25 3/7 weeks
should be plotted along the x axis between 25 and
26 weeks.
 Exact z-score and percentile calculator available fordownload from http://ucalgary.ca/fenton. Data isavailable for research upon request.
It may be more intuitive to plot on growth charts
using exact ages rather than on the basis of complete

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Figure 11 Comparison of the revised growth chart for boys (solid curves) and the 2003 Fenton growth chart (dashed curves) 3rd, 50th,and 97th percentile curves for length, head circumference, and weight). Both the 2003 and the revised growth curves are shown shifted toactual weeks.

weeks. Several years ago, the WHO used completed age
for growth chart development [12]. This recommendation was likely due to the way data had been collected in
the past, that is all 26 0/7 through 26 6/7 week infants
were included in the 26 week completed week category.
However, with the use of computers to plot on growth
charts comes the potential to more accurately plot measurements to the exact day of data collection. Thus thetime scale of the horizontal axes of these new growth
charts were re-scaled to actual age, for ease of use and understanding. For example, a baby at 25 3/7 can be intuitively plotted between 25 and 26 weeks.
Exact z-score and centile calculators for the revised
charts are available for download: http://ucalgary.ca/
fenton. Data is available for research upon request.
The data revealed that between 22 weeks to 50 weeks
post menstrual age, the fetus/infant multiplies its weight
tenfold, for example, the girls’ median weight increased
from a median of 520 to 5360 grams. Using a fetal-infant

growth chart allows clinicians to compare preterm infants’
growth to an estimated reference of the fetus and theterm infant.
There was a remarkably close fit of the included pretermsurveys for weight, head circumference and length fromthe 6 countries, especially at the 50th percentile, eventhough the data came from different countries.
The splining procedures we used have produced achart that has integrity and good agreement with theoriginal data. Smoothing of the LMS parameters is
recommended since minor fluctuations are more likely
due to sampling errors rather than physiological events[15]. Experts recommend that growth charts be developed
based on smoothed L, M and S, to constrain the adjacentcurves so that they relate to each other smoothly [15]. The
World Health Organization set their L parameter to 1 forhead circumference and length, while they maintained theexact L values for infants’ weights [58]. The data understudy here revealed the same effect as the WHO data; weFenton and Kim BMC Pediatrics 2013, 13:59
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found that both head circumference and length were closeenough to normal distributions that normal distributions
could summarize the data, while the exact L’s were needed
to retain the nuances of the weight curves.
The differences between the revised growth charts andthe 2003 Fenton preterm growth chart may reflect
improvements since the selected preterm growth references
for the new versions are more likely globally representativeof fetal and infant growth. Some of the differences between
the current charts and the 2003 version are likely due tothe separation into girl and boy charts, since the shiftsof the girls’ curves tend to be downward and the boys’
curves upward. The weight shifts after 40 weeks were
upward for both sexes, due to the higher values for the
WHOGS compared to the CDC growth reference [59] at
10 weeks post term.
The ideal growth pattern of preterm infants remains
undefined. These revised growth charts were developed
based on the growth patterns of the fetus (as has been
determined by size at birth in the large population studies) and the term infant (based on the WHO GrowthStandard) [2]. Ultrasound studies and comparison ofsubgroups of prematurely born infants suggest that the
fetal studies, such as those used in this development, may
be biased by the premature birth since fetuses who remain
in utero likely differ in important ways from babies whoare born early [60,61]. However, fetal size from theseimperfect studies may be the best data available at thispoint in time for comparing the growth of preterm infants
since the alternative, to compare to in utero infants
requires extrapolation from ultrasound measurements. To
use other premature infants as the growth reference forpreterm infants may not be ideal since the ideal growth ofpreterm infants has not been defined, has been changing
over time [62], and is influenced by the nutrition andmedical care received after birth [63,64].
Although the WHOGS is considered to be a growthstandard, the infants in the population-based surveys ofsize at birth are more likely representative of the reference
populations and were not selected to be healthy. Thus
these growth charts are growth references and are not a
growth standard. The INTERGROWTH study, currently
underway, will rectify this problem, since their purpose isto develop prescriptive standards for fetal and preterm
growth [65].

Conclusion
The inclusion of data from a number of developed countries
increases the generalizability of the growth chart. The
revised preterm growth chart, harmonized with the World
Health Organization Growth Standard at 50 weeks, may
support an improved transition of preterm infant growthmonitoring to the WHO charts.

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Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
The author’s responsibilities were as follows: JHK suggested the study, TRF &JHK designed the study and conducted independent literature searches, TRF
extracted the data, performed the statistical analysis, and wrote themanuscript. Both of the authors contributed to interpret the findings andwriting the manuscript, and both authors read and approved the final
manuscript.
Acknowledgements
Many thanks to Patrick Fenton and Misha Eliasziw for statistical assistance,
Roseann Nasser, Reg Sauve, Debbie O’Connor, and Sharon Unger forencouragement and advice, and Jayne Thirsk for editing advice.
Author details
1
Alberta Children’s Hospital Research Institute, The University of Calgary,
Calgary, AB, Canada. 2Department of Community Health Sciences, The
University of Calgary, 3280 Hospital Drive NW, Calgary, AB, Canada. 3Divisionof Neonatology, UC San Diego Medical Center, 200 West Arbor Drive MPF
1140, San Diego, CA, USA.
Received: 12 October 2012 Accepted: 10 April 2013
Published: 20 April 2013
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doi:10.1186/1471-2431-13-59
Cite this article as: Fenton and Kim: A systematic review and metaanalysis to revise the Fenton growth chart for preterm infants. BMC
Pediatrics 2013 13:59.

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