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DOI: 10.1542/peds.2003-0668-F
2004;114;970-980 Pediatrics
B. Lynne Hutchison, Luke A.D. Hutchison, John M.D. Thompson and Ed A. Mitchell
Cohort Study
Plagiocephaly and Brachycephaly in the First Two Years of Life: A Prospective
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rights reserved. Print ISSN: 0031-4005. Online ISSN: 1098-4275.
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Plagiocephaly and Brachycephaly in the First Two Years of Life:
A Prospective Cohort Study
B. Lynne Hutchison, DipHSc, PG DipSc*; Luke A.D. Hutchison, BSc (Hons), MS‡;
John M.D. Thompson, PhD*; and Ed A. Mitchell, DCH, FRACP, FRCPCH, DSc (Med)*
ABSTRACT. Objectives. Although referrals for non-
synostotic plagiocephaly (NSP) have increased in recent
years, the prevalence, natural history, and determinants
of the condition have been unclear. The objective of this
study was to assess the prevalence and natural history of
NSP in normal infants in the first 2 years of life and to
identify factors that may contribute to the development
of NSP.
Methods. Two hundred infants were recruited at
birth. At 6 weeks, 4 months, 8 months, 12 months, and 2
years, the head circumference shape was digitally photo-
graphed, and head shape was quantified using custom-
written software. At each age, infants were classified as
cases when the cephalic index was >93% and/or the
oblique cranial length ratio was >106%. Neck rotation
and a range of infant, infant care, socioeconomic, and
obstetric factors were assessed.
Results. Ninety-six percent of infants were followed
to 12 months, and 90.5% were followed to 2 years. Prev-
alence of plagiocephaly and/or brachycephaly at 6 weeks
and 4, 8, 12, and 24 months was 16.0%, 19.7%, 9.2%, 6.8%,
and 3.3% respectively. The mean cephalic index by 2
years was 81.6% (range: 72.0%–102.6%); the mean oblique
cranial length ratio was 102.6% (range: 100.1%–109.4%).
Significant univariate risk factors of NSP at 6 weeks
include limited passive neck rotation at birth, preferen-
tial head orientation, supine sleep position, and head
position not varied when put to sleep. At 4 months, risk
factors were male gender, firstborn, limited passive neck
rotation at birth, limited active head rotation at 4 months,
supine sleeping at birth and 6 weeks, lower activity level,
and trying unsuccessfully to vary the head position when
putting the infant down to sleep.
Conclusions. There is a wide range of head shapes in
infants, and prevalence of NSP increases to 4 months but
diminishes as infants grow older. The majority of cases
will have resolved by 2 years of age. Limited head rota-
tion, lower activity levels, and supine sleep position
seem to be important determinants. Pediatrics 2004;114:
970–980; plagiocephaly, brachycephaly, anthropometry,
cohort studies, infant care, supine position.
ABBREVIATIONS. NSP, nonsynostotic plagiocephaly; SIDS, sud-
den infant death syndrome; OCLR, oblique cranial length ratio;
PDQ-II, Revised Denver II Prescreening Questionnaire; PAT, Pic-
torial Assessment of Temperament; OR, odds ratio; CI, confidence
interval.
T
he rising incidence of nonsynostotic plagio-
cephaly (NSP) has been documented in the
literature since 1992 and has been attributed to
the adoption of the supine sleep position in accor-
dance with sudden infant death syndrome (SIDS)
prevention recommendations.
1
A critical review of
the literature in 1998 concluded that the actual prev-
alence is unknown and that the condition was being
recognized more frequently as a result of increased
awareness.
2
Many facets of the plagiocephalic condition are
unclear.
3
However, it has been shown that NSP is
more likely to occur in boys,
4–7
firstborns,
8,9
prema-
ture infants,
10
and those who sleep in the supine
position.
10,11
A preferred head orientation
12,13
and
limited head rotation
6
may be important determi-
nants. Varying the head position and tummy time
seem to be protective, whereas developmental delay
and lower activity levels may be associated with
cases.
11
Although positional preference has been fol-
lowed prospectively,
13
no prospective cohort studies
of normal infants that have investigated the preva-
lence of NSP and quantified the development of
head shape in the first 2 years have been undertaken.
Strictly speaking, brachycephaly, or a high ce-
phalic index without noticeable skewness of the
head, is not true plagiocephaly, which means
“oblique head.” In NSP, a high cephalic index is
sometimes but not always associated with asymme-
try. However, as our clinical experience indicates
that central occipital flattening is as concerning to
parents as the skewed head shape, we have chosen to
combine them. It is possible that the mechanisms are
the same, the flat area merely corresponding to the
preferred resting position, and any associated boss-
ing reflecting different areas of displacement of head
volume. Alternatively, it has been postulated that
plagiocephaly with asymmetry may more commonly
originate from neck muscle dysfunction, whereas
brachycephaly results from compression.
14
We have developed a new head shape measuring
technique, HeadsUp, which involves an elastic head
circumference band that is photographed digitally
from above the head. The photograph is analyzed
using a custom-written computer program to obtain
measurements to quantify the head shape. The
From the *Department of Paediatrics, University of Auckland, Auckland,
New Zealand; and ‡Computer Science Department, Brigham Young Uni-
versity, Provo, Utah.
Accepted for publication Mar 16, 2004.
doi:10.1542/peds.2003-0668-F
Reprint requests to (L.H.) Department of Paediatrics, University of Auck-
land, Private Bag 92019, Auckland, New Zealand. E-mail: bl.hutchison@
auckland.ac.nz
PEDIATRICS (ISSN 0031 4005). Copyright © 2004 by the American Acad-
emy of Pediatrics.
970 PEDIATRICS Vol. 114 No. 4 October 2004
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method has been used successfully in a pilot study of
60 infants and demonstrated much greater reliability
and acceptability compared with measurements ob-
tained using a flexible measuring strip.
15
We have
identified cutoff points for both cephalic index and
oblique cranial length ratio (OCLR; ie, the ratio of the
long cross-diagonal measurement to the shorter
cross-diagonal measurement). Beyond these thresh-
olds, central occipital flattening and head shape
asymmetry, respectively, are deemed to be abnor-
mal. In practice, we believe that these cutoffs approx-
imate the points at which head deformity becomes
visually obvious, particularly where the infant has
little hair. The points, 93% for cephalic index and
106% for OCLR, allow for the allocation of the cohort
infants to either case or control. We aimed to deter-
mine the prevalence, natural history, and risk factors
of NSP in the first 2 years of life.
METHODS
The cohort infants were born at the delivery unit at North Shore
Hospital, Auckland, a community maternity unit that deals with
low-risk deliveries. On admission to the unit, the mother had the
opportunity to opt out of being approached regarding research.
The researcher was given a birth list each day, with the names of
those who opted out deleted from this list. Selection of every
fourth infant on the list yielded a cohort of 238 born between
September 2001 and February 2002. Infants with congenital defor-
mities, those who were not domiciled in the Waitemata Health
District, those who were planning to move out of the region in the
next year, and those who could not be seen in the first week were
excluded.
Of the eligible mothers who were invited to participate, 200
(88%) were enrolled in the study (Fig 1). The initial interview was
conducted either in the postnatal ward or in the mother’s home
within the first week after delivery. At this interview, the mother
was asked about sociodemographic factors (parents’ ages, ethnic-
ity, occupation, and mother’s education), obstetric factors (parity,
gestation, presentation, method of delivery, length of labor, and
multiple birth), and infant details such as date of birth, gender,
Apgar scores, and birth measurements. The mother’s highest ed-
ucational level was classified into 1) no qualifications or 1 or more
School Certificate (year 11) subjects, 2) sixth form or Bursary
qualification (years 12–13), and 3) tertiary education or profes-
sional certification. The parents’ occupations were rated in accor-
dance with the New Zealand Socio-economic Index of Occupa-
tional Status
16
classifications into high, medium, and low
socioeconomic status, the highest rating of either parent being
used for the classification.
The interviewer assessed the infant’s head shape for anything
unusual, such as a caput or area of flattening. When possible,
when the infant was in a relaxed state, passive head rotation was
assessed. This was accomplished by standing behind the supine-
lying infant, holding the head between the hands, and gently
rotating the head from side to side. Any restriction or tightness in
1 or both directions was noted. The head circumference was
measured around the maximum fronto-occipital circumference.
At 6 weeks, 4 months, 8 months, 12 months, and 24 months, the
mother and the infant were visited at home, and a set of digital
photographs of the infant’s head using the HeadsUp band were
taken to document the head shape, as follows. While seated on the
mother’s knee (or on the floor for older infants), the infant was
given 1 or 2 toys to play with if necessary while a close-fitting,
nylon stocking–type cap was placed on the head to flatten the hair.
The infant’s identification was written on a yellow sticker and
attached to the stocking cap. A small yellow cape was placed over
the shoulders to mask any competing colors in the clothing or
surroundings. A soft, elastic, blue headband made of a narrow
strip of 7-mm-thick covered neoprene was then placed over the
head circumference. On the headband are sliding green ear mark-
ers and a red marker to indicate the middle of the nose. The red
marker is also a known length (50 mm), which is used to deter-
mine scale. After positioning the band and the markers, digital
photographs were taken from ⬃800 mm above the vertex of the
head, using a Sony DSC-S50 digital still camera with pivoting LCD
viewing screen. Several photographs were taken, and the 3 best
were kept for analysis by the HeadsUp computer program. The
mean measurements taken from the 3 photographs were used in
the final analysis. We did not use the HeadsUp photographic
measure on the newborns because of possible birth molding of the
head.
The main measure of asymmetry from one side of the head to
the other was the OCLR. These lines were taken from points
located 40 degrees either side of the posterior midline, obliquely
across the head to derived frontozygomatic points in the frontal
area of the head circumference. The other important measure used
was the cephalic index, a measure of central posterior flattening or
brachycephaly, calculated from (head breadth/head length) ⫻
100. Criteria to allocate case definition were made previously
using analyses of mean cephalic indices and OCLR measurements
obtained from a pilot photograph study (unpublished data). The
criteria so defined require that the cephalic index be 93% or above
and/or OCLR be 106% or above. Other measurements assessed
were head circumference, head area bounded by the blue band,
angles of each ear relative to the nose position, and transcranial
difference in millimeters.
At 6 weeks, the infant’s passive head rotation was assessed as
for the newborns. At 4, 8, 12, and 24 months, active head rotation
was checked by seating the infant facing outward on the mother’s
knee, then holding a bright musical toy in front of the infant. The
toy was brought around to each side to encourage the infant to
follow the toy with the eyes until they were looking across the
shoulder, without moving the body around with the head. Any
limitation or difficulty in head rotation was recorded.
At each of the follow-up interviews, the mother was asked
about such factors as weight, length, and head circumference
measurements as recorded in the child’s Well Child Record Book
(a parent-held community child health nursing record), health
problems, hair loss, and the presence of preferential head turning
or neck dysfunction. In addition, she was asked about infant care
practices such as breastfeeding; pacifier use; sleep position; head
varying; total daily duration of tummy time and upright time; bed
type; mattress type; underbedding; pillow use; preferred maternal
holding positions; and amount of time spent in supine in cots, car
seats, bouncers, and other places per day on average.
At the 6-week interview, the mother was given the Revised
Denver II Prescreening Questionnaire (PDQ-II)
17
and was asked to
go through the items until 3 “no” responses were recorded. At
each subsequent interview, she was asked to reassess the previous
“no” responses and then to continue the items until 3 “no” re-
sponses were recorded again. The 0- to 9-month and 9- to 24-
month forms were used. The number of delays and/or cautions
for the child’s age was recorded. Children with no delays and 1 or
no cautions were rated normal. If a child had 1 delay or 2 cautions,
then the rating was slightly abnormal, and 2 or more delays or 3
or more cautions were rated abnormal.
Temperament assessment using the Pictorial Assessment of
Temperament (PAT)
18
was conducted at 4 months. This consists of
a 10-item measure of temperament based on Carey’s Revised
Infant Temperament Questionnaire and consists of vignettes de-
Fig 1. Enrollment of subjects.
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picting 3 different types of response to 10 different situations, such
as getting dressed, waking up, loud noises, etc. The response types
are “easy,”“average or slow-to-warm-up,” and “difficult.” A
score of 1 is given for “easy” responses, 2 for “average or slow-
to-warm-up” responses, and 3 for “difficult” responses, giving a
total possible score range of between 10 and 30.
Temperament was also assessed at each age by showing the
mother a plastic gauge with a slider on it. At 1 end is a happy face
and the words “very settled/easy-going,” and at the other end is
an unhappy face and the words “very unsettled/difficult.” The
mother was asked to position the slider to indicate the child’s
overall temperament at that age. The other side of the gauge is
marked with a scale from 0 to 10, and the researcher thus was able
to assign a score for the mother’s assessment. Activity level at each
age was similarly assessed by the mother, with the gauge scoring
between “very inactive” (score ⫽ 0) and “very active” (score ⫽ 10).
The interviewer assessed mattress softness using a subjective
rating of soft, medium, or firm. A weight (10.5 g/cm
2
)ona
6-mm-diameter aluminum plunger gauged in 1-mm increments,
which was dropped onto the mattress through a hole in a small
circle of wood, also gave an objective assessment of the mattress
firmness. If the mattress was extremely hard, then the weight
dropped very little, giving a reading close to 0 mm, whereas very
soft mattresses gave a higher reading of up to 30 mm. When the
mattress was not available, the mother was asked to rate it as soft,
medium, or firm.
Baseline data were collected at the first interview. The data
were analyzed as a standard case-control analysis using univariate
and multivariate logistic regression, using SAS (Release 8.2; SAS
Institute, Cary, NC).
All interviews were conducted by the principal investigator,
with the exception of some 6-week and 4-month interviews that
were done by 1 other trained interviewer. No advice was offered
to parents of children who developed a misshapen head shape;
however, if at any time a mother became concerned about head
shape problems developing in her infant, she was advised to talk
to her family doctor or Plunket nurse (community child health
nurse) for advice. The Auckland Ethics Committee approved the
study.
RESULTS
Cohort Characteristics
The infants who were enrolled in this study were
healthy infants who were mostly full term. Ninety-
one percent of the initial interviews were completed
in the first 36 hours. Of the 200 infants who were
enrolled in the study, 100% were seen at 6 weeks, 198
(99%) were seen at 4 months, 196 (98%) were seen at
8 months, 192 (96%) were seen at 12 months, and 181
(90.5%) were followed to 2 years. The characteristics
of the cohort are listed in Table 1.
Head Measurements
Newborn head shape was normal on visual assess-
ment for 63.0% of the cohort. Cone-shaped heads
were seen in 13.5% of the cohort; prominent or in-
dented sutures in 12%; and caputs, flat areas, or other
“bumps or dents” in 16%.
At the follow-up interviews, there was a wide
range for cephalic index and OCLR (Table 2). The
widest range for both occurred at 6 weeks, but
whereas the maximum OCLR reduced thereafter, the
maximum cephalic index was recorded at 12 months.
There was also a wide range of ear angle positions
seen particularly at the 6-week period, although no
difference was detected between cases and control
subjects at each age for ear angles or head circum-
ference. Head circumference as measured by tape
measure versus that measured by HeadsUp showed
a high correlation between the 2 types of measure (r
⫽ 0.98) over all ages. At follow-up and using the
HeadsUp measure, boys’ head circumferences were
significantly larger than girls’, being ⬃1 cm larger at
each age. There was no difference detected between
genders for cephalic index, OCLR, or ear angles.
The mean difference between the transcranial di-
ameters in the plagiocephalic infants was 9.8 mm
(SD: 2.0), 11.3 mm (SD: 0.6), 10.3 mm (SD: 0.9), 11.1
mm (SD: 1.2), and 12.0 mm (SD: 2.4), at 6 weeks and
4, 8, 12, and 24 months respectively.
Prevalence and Natural History
After each follow-up interview, any infant who
had a cephalic index of ⱖ93% and/or an OCLR of
ⱖ106% was classified as a case (see Fig 2). In Fig 2,
cases that were defined as normal for the purposes of
this study are in the lower left-hand quadrant,
brachycephalic cases are in the top left-hand quad-
rant, plagiocephalic cases are in the lower right-hand
quadrant, and those with both are in the top right-
hand quadrant.
Using the cutoff points of 93% for cephalic index
and 106% for OCLR, the numbers of cases and non-
cases at each age are illustrated in Figs 3 and 4.
Although half of the 6-week cases had resolved by 4
months, 23 new cases had occurred at 4 months.
Thereafter, few new cases occurred and the total
number of cases started diminishing so that by 12
months, there were only one third as many cases as
at 4 months. By the age of 2 years, only 6 (3.3%)
children recorded values outside the set parameters:
3 were brachycephalic and 3 were plagiocephalic.
TABLE 1. Cohort Description (n ⫽ 200)
Variable n (%)
Gender
Male 106 (53.0)
Female 94 (47.0)
Parity
Firstborn 90 (45.0)
Later born 110 (55.0)
Multiple birth
Singletons 199 (99.5)
Twin 1 (0.5)
Gestation
⬍37 wk 4 (2.0)
ⱖ37 wk 196 (98.0)
Delivery
Normal vaginal 133 (66.5)
Cesarean 41 (20.5)
Assisted vaginal 26 (13.0)
5-Min Apgar score
⬍7 1 (0.5)
ⱖ7 199 (99.5)
Maternal age
⬍25 20 (10.0)
25–29 38 (19.0)
30–34 87 (43.5)
35⫹ 55 (27.5)
Mother’s highest qualification
None or school certificate 44 (22.3)
Sixth form/bursary 45 (22.9)
Tertiary/professional 108 (54.8)
Socioeconomic status
Low 22 (11.0)
Medium 111 (55.5)
High 67 (33.5)
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One of the 12-month cases was unable to be followed
to 2 years.
The overall prevalence rates for the cohort were
16% at 6 weeks, 19.7% at 4 months, 9.2% at 8 months,
6.8% at 12 months, and 3.3% at 24 months. More than
twice as many infants were classified as having pla-
giocephaly alone (OCLR ⱖ106%) than having
brachycephaly alone (cephalic index ⱖ93%) at 6
weeks, but at both 4 and 8 months, more infants were
classified as brachycephalic than plagiocephalic. This
Fig 2. Mean cephalic index and OCLR scores for all infants at each age (controls [normal] are in the lower left quadrants of each scatter
plot).
TABLE 2. Head Measurements (All Infants)
Variable 6 Weeks
(n ⫽ 200)
4 Months
(n ⫽ 198)
8 Months
(n ⫽ 196)
12 Months
(n ⫽ 192)
2 Years
(n ⫽ 181)
Mean
(SD)
Min Max Mean
(SD)
Min Max Mean
(SD)
Min Max Mean
(SD)
Min Max Mean
(SD)
Min Max
Cephalic
index
83.5 (5.7) 72.1 103.8 84.9 (6.2) 72.5 101.3 83.8 (5.7) 73.5 103.2 82.9 (5.4) 72.7 104.1 81.6 (4.8) 72.0 102.6
OCLR 103.2 (2.5) 100.2 112.2 102.9 (2.1) 100.2 109.5 102.5 (1.7) 100.1 108.1 102.5 (1.7) 100.2 108.8 102.6 (1.7) 100.1 109.4
HC 38.2 (1.3) 34.1 41.6 41.7 (1.2) 38.9 44.8 44.8 (1.4) 41.4 49.0 46.5 (1.4) 42.8 49.6 48.6 (1.3) 45.3 51.8
L ear
angle
90.2 (4.6) 75.7 99.5 90.6 (3.1) 82.3 98.3 89.5 (3.5) 80.7 102.0 89.3 (3.1) 80.0 97.3 88.1 (3.3) 80.3 97.0
R ear
angle
89.9 (4.6) 80.5 104.7 89.5 (3.1) 81.7 97.7 90.5 (3.5) 78.0 99.3 90.7 (3.1) 83.0 100.0 91.9 (3.3) 83.0 99.7
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difference had disappeared by 12 months, with rates
for both dropping considerably by that age. In the
early months, a few infants were classified as having
both plagiocephaly and brachycephaly (Table 3).
Overall, 29.5% of the cohort infants developed ei-
ther plagiocephaly or brachycephaly or both at some
stage during the study observation period (Table 3);
however, by the age of 2 years, only 3.3% were still
above the classification threshold for abnormality
(Table 3). Most cases manifested at 6 weeks or 4
Fig 3. Percentage of the cohort who
were cases at each age.
Fig 4. Development of plagiocephaly or brachycephaly in the cohort in the first 2 years. (The numbers in shaded areas represent cases.
Slight discrepancies in numbers are attributed to small numbers lost to follow-up at 4, 8, 12, and 24 months.)
974 PLAGIOCEPHALY IN THE FIRST TWO YEARS OF LIFE
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months; only 4 new cases had developed at 8
months, and thereafter no infant developed deforma-
tion. If the cutoff points were different, then the
prevalence of cases at each age would be found to be
different. Table 4 shows how prevalence would
change if the limits were set at lower or higher levels.
Fifteen case mothers consulted their Plunket nurse
or general practitioner regarding their infants’ head
deformity. One case was also seen by a physiother-
apist. Treatment consisted of positioning advice in 9
cases; reassurance only was given in the other 6
cases. Although helmet treatment is available in New
Zealand, no case was considered severe enough to be
referred for such treatment by their health profes-
sional.
Of the 6 2-year cases, there were 3 boys and 3 girls,
and 5 were firstborns. All slept supine in the early
months. Two of the 3 brachycephalic cases were
above the cephalic index cutoff at all ages; the most
severe case, a girl born at 36 weeks’ gestation, was
just below 93% at 6 weeks and thereafter was con-
sistently over 100%. Although her parents had been
concerned at 4, 8, and 12 months, by 2 years, they
were not particularly worried. Head rotation tests
were normal at all ages. In the plagiocephalic cases,
1 case progressively worsened to 8 months, and the
OCLR thereafter remained about the same, at
⬃109%. She showed evidence of head tilt and limited
rotation at 4 and 8 months. The mother remarked at
2 years that she still leaned to 1 side when she was
tired. This mother was also unconcerned at 2 years.
The other 2 plagiocephalic cases’ OCLRs tended to
vacillate around the cutoffs. One had mild unilateral
flattening of the forehead at age 2 years but other-
wise looked almost normal. No parent of a 2-year
case was concerned about the head shape; 1 control
parent expressed mild concern about her son, whose
head had improved since 8 months but was still
slightly flat in a small area above the band.
Risk Factors: 6 Weeks
Owing to the small number of cases at 8, 12, and 24
months, analysis of risk factors was restricted to 6
weeks and 4 months. Six-week cases were signifi-
cantly more likely to have had a limitation of passive
rotation at the newborn interview (crude odds ratio
[OR]: 6.17; 95% confidence interval [CI]: 2.03–18.76;
Table 5), although no difference was detected in the
passive head rotation test performed at 6 weeks.
More case mothers reported a preferential head ori-
entation at 6 weeks, although this was of borderline
significance.
Ninety-four percent of 6-week cases had been po-
sitioned for supine sleep at the newborn interview,
compared with 56.5% of control subjects (crude OR:
11.53; 95% CI: 2.67– 49.81). By 6 weeks, 81.3% of cases
were still sleeping supine, compared with 48.2% of
control subjects (crude OR: 4.65; 95% CI: 1.82–11.89).
The mothers of cases were less likely to be varying
the head position when putting the infant down to
sleep (crude OR: 2.75; 95% CI: 1.11– 6.82), or they
were trying to vary it but were not able to owing to
the infant’s turning to his or her own preferred po-
sition (crude OR: 5.15; 95% CI: 1.90–13.98).
When the total amount of back time was added up,
the cases were spending a mean of 19.0 (SD: 4.1)
hours a day on their back, compared with control
subjects at 14.9 (SD: 6.5) hours (P ⬍ .0001). Half of the
case infants were spending ⬎21 hours a day supine,
compared with 23.8% of control infants (crude OR:
3.20; 95% CI: 1.47–6.97), although cases were more
likely than control subjects to be spending ⬎1 hour a
day upright (crude OR: 2.50; 95% CI: 1.08–5.56). Case
infants spent more time than control infants lying in
bouncy seats or rockers, although this reached only
marginal significance (P ⫽ .08). Two (6.3%) cases and
3 (1.8%) control subjects had 2 or more developmen-
tal delays or 3 or more cautions on the PDQ-II.
TABLE 3. New Cases at Each Age
Condition 6 Weeks
(n [%])
4 Months
(n [%])
8 Months
(n [%])
12 Months
(n [%])
2 Years
(n [%])
Total
(% of
original
cohort)
Either 32 (16.0) 23 (11.6) 4 (2.0) 0 (0.0) 0 (0.0) 59 (29.5)
Plagiocephaly only 21 (10.5) 12 (6.1) 3 (1.5) 0 (0.0) 0 (0.0) 36 (18)
Brachycephaly only 9 (4.5) 11 (5.6) 1 (0.5) 0 (0.0) 0 (0.0) 21 (10.5)
Both 2 (1.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 2 (1.0)
TABLE 4. Prevalence of Plagiocephaly Using Different Cutoff Criteria
Cutoff 6-Week Cases
(n [%])
4-Month Cases
(n [%])
8-Month Cases
(n [%])
12-Month Cases
(n [%])
2-Year Cases
(n [%])
Cephalic index ⱖ91% and/or
OCLR40 ⱖ105%
51 (25.5) 56 (28.0) 37 (18.9) 36 (18.7) 23 (12.7)
Cephalic index ⱖ92% and/or
OCLR40 ⱖ105.5%
39 (19.5) 49 (24.7) 26 (13.3) 20 (10.4) 12 (6.6)
Cephalic index ⱖ93% and/or
OCLR40 ⱖ106%
32 (16.0) 39 (19.7) 18 (9.2) 13 (6.8) 6 (3.3)
Cephalic index ⱖ94% and/or
OCLR40 ⱖ106%
30 (15.0) 36 (18.2) 18 (9.2) 12 (6.3) 6 (3.3)
Cephalic index ⱖ95% and/or
OCLR40 ⱖ107%
24 (12.0) 19 (9.6) 10 (5.1) 8 (4.2) 5 (2.8)
ARTICLES 975
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Factors that were significant at the univariate level
all were entered into an initial multivariate model,
with the exception of newborn sleep position, which
had low numbers in 1 category. The multivariate
model was reduced by removing variables that were
nonsignificant 1 at a time to ensure they did not
affect risk estimates of the other variables. The vari-
ables that remained significant in the final multivar-
iate model were newborn passive head rotation (ad-
justed OR: 9.51; 95% CI: 2.59–34.94), 6-week sleep
position (adjusted OR: 5.27; 95% CI: 1.81–15.39), and
upright time (adjusted OR: 3.99; 95% CI: 1.42–11.23).
No significant differences were detected between
cases and control subjects at 6 weeks for obstetric
factors, socioeconomic factors, gender, newborn
head circumference, abnormal head shape at the
newborn assessment, the presence of hair loss on the
back of the head, snoring, activity level, newborn or
6-week weight, length and head circumference, tem-
perament rating, activity level, the amount of re-
ported tummy time per day, breastfeeding, dummy
use, the use of positioning aids or pillows, mattress
firmness, maternal hand dominance, and the moth-
er’s preferred holding position.
Risk Factors: 4 Months
At 4 months, male gender was of borderline sig-
nificance (crude OR: 2.03; 95% CI: 0.97– 4.22), as was
being firstborn (crude OR: 1.82; 95% CI: 0.90 –3.70).
The 4-month cases were still significantly more likely
to have had a limitation of passive head rotation at
the newborn interview (crude OR: 7.78; 95% CI:
2.56–23.70), and they were also more likely to have a
limitation of active head rotation at the 4-month
interview (crude OR: 2.68; 95% CI: 1.23–5.81;
Table 6).
In the 4-month cases, having slept supine at 6
weeks was significant (crude OR: 2.33; 95% CI: 1.11–
4.93), but sleeping supine at 4 months was not. Sim-
ilarly, having tried unsuccessfully to vary the head
position when putting the infant to sleep at 6 weeks
was significant (crude OR: 4.23; 95% CI: 1.74–10.28);
however, unsuccessfully varying the head position at
4 months was only marginally significant (crude OR:
2.68; 95% CI: 0.97–7.43). More cases than control
subjects had ⬎21 hours of back time at 6 weeks
(crude OR: 2.43; 95% CI: 1.47–5.20), but total back
time at 4 months was not significantly different. Us-
ing a pillow reached marginal significance (crude
OR: 2.64; 95% CI: 0.97–7.24).
Although the numbers were small, the 4-month
cases were more likely to have had an abnormal
result on the 6-week PDQ-II test (crude OR: 18.06;
95% CI: 1.96–166.54). The mothers of 4-month cases
were also more likely to report snoring in their in-
fants (crude OR: 5.60; 95% CI: 1.61–19.45) and to
report that their infants had low activity levels (crude
OR: 3.28; 95% CI: 1.40 –7.75). Infants who were cases
at 4 months sat alone at a slightly older age than
those who were control subjects at 4 months (6.7
months [SD: 0.98] vs 6.4 months [SD: 0.97]; P ⫽ .05).
One third of infants scored 15 or less on the PAT
test administered at this age, and we categorized
these infants as “easy.” Case infants were more likely
to score in the average to difficult range (ⱖ16) for
infant temperament than in the easy range (crude
OR: 2.63; 95% CI: 1.09 –6.32). However, there was
no difference between cases and control subjects for
the temperament gauge score assessment by the
mothers.
Multivariate analysis of the factors that were sig-
nificant at the univariate level led to a final multi-
TABLE 5. Significant Risk Factors at 6 Weeks
Variable Case
(n ⫽ 32; n
[%])
Control
(n ⫽ 168; n [%])
Univariate OR
(95% CI, P Value)
Multivariate OR
(95% CI, P Value)
Limitation of passive rotation - newborn
(missing ⫽ 16)
2
⫽ 12.52, P ⫽ .0004
2
⫽ 11.50, P ⫽ .0007
Limited 7 (25.0) 8 (5.1) 6.17 (2.03–18.76) 9.51 (2.59–34.94)
Not limited 21 (75.0) 148 (94.9) 1.00 1.00
Reported preferential head orientation
(missing ⫽ 2)
2
⫽ 3.19, P ⫽ .07
Yes 23 (71.9) 91 (54.8) 2.11 (0.92–4.83)
No 9 (28.1) 75 (45.2) 1.00
Sleep position at newborn interview P ⬍ .0001
Supine only 30 (93.8) 95 (56.5) 11.53 (2.67–49.81)
Nonsupine 2 (6.2) 73 (43.5) 1.00
Sleep position at 6 wk
2
⫽ 11.79, P ⫽ .0006
2
⫽ 9.25, P ⫽ .003
Supine only 26 (81.3) 81 (48.2) 4.65 (1.82–11.89) 5.27 (1.81–15.39)
Nonsupine 6 (18.7) 87 (51.8) 1.00 1.00
Head position varied
2
⫽ 10.94, P ⫽ .004
Yes 10 (31.2) 103 (61.3) 1.00
No 12 (37.5) 45 (26.8) 2.75 (1.11–6.82)
Tried but unsuccessful 10 (31.2) 20 (11.9) 5.15 (1.90–13.98)
Back time per day
2
⫽ 8.57, P ⫽ .003
⬍ 21 h 16 (50.0) 128 (76.2) 1.00
ⱖ 21 h 16 (50.0) 40 (23.8) 3.20 (1.47–6.97)
Upright time per day
2
⫽ 4.90, P ⫽ .03
2
⫽ 6.88, P ⫽ .009
ⱕ 1 h 9 (28.1) 83 (49.4) 1.00 1.00
⬎ 1 h 23 (71.9) 85 (50.6) 2.50 (1.08–5.56) 3.99 (1.42–11.23)
Backtime per day (h) 19.01 (4.13) 14.89 (6.52) P ⬍ .0001

⫽ 0.14 (0.05–0.22)
976 PLAGIOCEPHALY IN THE FIRST TWO YEARS OF LIFE
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variate model in which the following variables were
found to be significant: limited passive head rotation
at birth (adjusted OR: 6.51; 95% CI: 1.85–22.98), lim-
ited active head rotation at 4 months (adjusted OR:
3.11; 95% CI: 1.21–8.05), tried but unable to vary
head position at 6 weeks (adjusted OR: 4.28; 95% CI:
1.58–11.59), low activity level at 4 months (adjusted
OR: 3.28; 95% CI: 1.16–9.29), and average to difficult
rating on PAT test (adjusted OR: 3.30; 95% CI: 1.17–
9.29; Table 6).
No significant differences were found in the
4-month cases for obstetric factors; socioeconomic
factors; newborn head circumference; abnormal head
shape at newborn assessment; weight, length, and
head circumference measured at the 3-month well-
child check; preferential head orientation; develop-
mental delays either reported or on the PDQ-II; num-
ber of cautions or delays on the PDQ-II; sleep
position at 4 months; hair loss, tummy time, and
back time at 4 months; upright time; bouncinette
time; breastfeeding; preferred side of feeding;
dummy use; the use of positioning aids; mattress
firmness; mother’s handedness; and preferred hold-
ing position.
DISCUSSION
Our cohort revealed a wide range of head shape,
with cephalic index in the cohort ranging from 72 to
104 and OCLR ranging from 100 to 112 in the first 2
years of life. OCLR range was wide in the early
period and reduced over time, whereas cephalic in-
dex took longer to develop and subsequently to re-
duce. The wide range of both cephalic index and
OCLR at 6 weeks probably reflects the extreme mal-
leability of the infant cranium in the newborn period.
However, it is a matter of conjecture how much of
this is attributable to forces acting on the cranium
and how much is attributable to genetic tendencies.
TABLE 6. Significant Risk Factors at 4 Months
Variable Case
(n ⫽ 39;
n [%])
Control
(n ⫽ 161;
n [%])
Univariate OR
(95% CI)
Multivariate OR
(95% CI)
Gender (missing ⫽ 2)
2
⫽ 3.54, P ⫽ .06
Male 26 (66.7) 79 (49.7) 2.03 (0.97–4.22)
Female 13 (33.3) 80 (50.3) 1.00
Parity (missing ⫽ 2)
2
⫽ 2.77, P ⫽ .09
Firstborn 22 (56.4) 66 (41.5) 1.82 (0.90–3.70)
Later born 17 (43.6) 93 (58.5) 1.00
Limitation of passive rotation - newborn
(missing ⫽ 16)
2
⫽ 13.07, P ⫽ .0003
2
⫽ 8.49, P ⫽ .004
Limited 9 (25.0) 6 (4.1) 7.78 (2.56–23.70) 6.51 (1.85–22.98)
Not limited 27 (75.0) 140 (95.9) 1.00 1.00
Active rotation at 4 months (missing ⫽ 5)
2
⫽ 6.20, P ⫽ .02
2
⫽ 5.50, P ⫽ .02
Limitation 14 (35.9) 27 (17.3) 2.68 (1.23–5.81) 3.11 (1.21–8.05)
No limitation 25 (64.1) 129 (82.7) 1.00 1.00
Sleep position at newborn interview
(missing ⫽ 2)
2
⫽ 3.02, P ⫽ .08
Supine only 29 (74.4) 94 (59.1) 2.01 (0.91–4.40)
Nonsupine 10 (25.6) 65 (40.9) 1.00
Sleep position at 6 wk (missing ⫽ 2)
2
⫽ 5.11, P ⫽ .02
Supine only 27 (69.2) 78 (49.1) 2.33 (1.11–4.93)
Nonsupine 12 (30.8) 81 (50.9) 1.00
Head position varied at 6 wk (missing ⫽ 2)
2
⫽ 11.28, P ⫽ .004
2
⫽ 9.20, P ⫽ .01
Yes 17 (43.6) 94 (59.1) 1.00 1.00
No 9 (23.1) 48 (30.2) 1.04 (0.43–2.50) 1.04 (0.36–3.00)
Tried but unsuccessful 13 (33.3) 17 (10.7) 4.23 (1.74–10.28) 4.28 (1.58–11.59)
Head position varied at 4 mo (missing ⫽ 2)
2
⫽ 4.97, P ⫽ .08
Yes 9 (23.1) 46 (28.9) 1.00
No 19 (48.7) 92 (57.9) 1.06 (0.44–2.52)
Tried but unsuccessful 11 (28.2) 21 (13.2) 2.68 (0.97–7.43)
Back time per day at 6 wk (missing ⫽ 2)
2
⫽ 6.05, P ⫽ .01
⬍ 21 hours 22 (56.4) 121 (76.1) 1.00
ⱖ 21 hours 17 (43.6) 38 (23.9) 2.43 (1.47–5.20)
Pillow used (missing ⫽ 3)
2
⫽ 3.57, p ⫽ .06
Yes 7 (18.0) 12 (7.6) 2.64 (0.97–7.24)
No 32 (82.0) 145 (92.4) 1.00
PDQ-II delays at 6w (missing ⫽ 2) P ⫽ .005 (Fisher)
Normal / slightly abnormal 35 (89.7) 158 (99.4) 1.00
Abnormal: ⬎1 delay or ⬎ 2 cautions 4 (10.3) 1 (0.6) 18.06 (1.96–166.54)
Snoring (missing ⫽ 2)
2
⫽ 7.36, P ⫽ .007
Yes 6 (15.4) 5 (3.1) 5.60 (1.61–19.45)
None/minimal 33 (84.6) 154 (96.9) 1.00
Activity level at 4m categorised (missing ⫽ 2)
2
⫽ 7.34, P ⫽ .007
2
⫽ 4.98, P ⫽ .03
Low: ⬍ 6.5 11 (28.2) 17 (10.7) 3.28 (1.40–7.75) 3.28 (1.16–9.29)
High: ⬎⫽6.5 28 (71.8) 142 (89.3) 1.00 1.00
PAT (temperament test) categorized
(missing ⫽ 2)
2
⫽ 4.63, P ⫽ .03
2
⫽ 5.09, P ⫽ .02
Easy: ⬍16 7 (17.9) 58 (36.5) 1.00 1.00
Average-difficult: ⱖ16 32 (82.1) 101 (63.5) 2.63 (1.09–6.32) 3.30 (1.17–9.29)
ARTICLES 977
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The infants in our cohort had wider heads than
recorded in an earlier report of normal children. Our
mean cephalic indices at 6 weeks and 4, 8, 12, and 24
months were 83.5, 84.9, 83.8, 82.9, and 81.6, respec-
tively. In comparison, mean cephalic indices pub-
lished in 1977 for 1 month, 4 months, 9 months, 12
months, and 2 years, based on sample sizes of ⬃40
American infants, were 79.5, 78.2, 78.6, 76.7, and 76.9,
respectively.
19
These much lower indices were re-
corded at a time when prone and side sleeping were
frequently the norm. A group of Taiwanese cleft-lip
infants were shown to have a cephalic index of 93.0%
at 3 months when they slept supine, compared with
82.6 when they slept prone.
20
Ethnic differences may
explain some of the variation as there is some evi-
dence of anatomic differences relating to racial ori-
gins.
21
The true prevalence of NSP has been unclear,
largely because of disparities in diagnostic criteria
and subjective classifications.
2
Quoted prevalence
varies between 0.3%, a figure derived from congen-
ital muscular torticollis rates in 1974,
22
to 48% of
under-1-year-olds in 1971, based on frontal measure-
ments.
23
Other early studies quoted 5%
24
and 28%,
25
but there were no definitions of plagiocephaly stated.
A more recent study of positional preference esti-
mated a plagiocephaly prevalence of 9.9% in all chil-
dren under the age of 6 months, based on nonquan-
tified visual assessment of asymmetry.
13
Diagnostic
disagreements relating to lambdoid synostosis and
NSP have also led to confusion in the literature.
There is agreement, however, that the prevalence of
NSP has increased and is linked with the adoption of
the supine sleep position for prevention of SIDS.
1
However, as we have shown, age affects preva-
lence rates. Using cutoff points of 93% for cephalic
index and 106% for OCLR, the point prevalence of
head shape deformity in our cohort was 16% at 6
weeks, 19.7% at 4 months, 9.2% at 8 months, 6.8% at
12 months, and 3.3% at 2 years. Nearly 30% of our
cohort exceeded the cutoff levels during the first
year, this being the period prevalence for the first
year of life in the cohort. It is notable that few new
cases appeared at 8 months and no new cases there-
after. Prevalence of either plagiocephaly or
brachycephaly or both increased between 6 weeks
and 4 months, decreased to one third of the 4-month
level by 1 year, and then halved again by 2 years.
Thus, 12.8% of 4-month cases were still cases at 2
years, 33.3% of 8-month cases were still cases at 2
years, and 46% of 12-month cases were still cases at
2 years. This is comparable to a Dutch study that
showed that 25% of infants who manifested asym-
metric head shape between 1 and 6 months still had
asymmetry by 2 to 3 years.
13
There did not seem to be any 1 factor that would
have predicted which infants remained in the case
group by age 2. However, it is obvious from our data
that although there may be some clinical abnormality
as the infant grows older, the level of parental con-
cern is extremely low. In speaking to the parents, this
seemed to be attributable mostly to hair growth ob-
scuring the abnormality of head shape, in addition to
the relative size of the problem appearing smaller as
the head grew. The mean difference in transcranial
diameters in the cases increased by only 2.2 mm
between 6 weeks and 2 years of age. This raises the
issue of whether our definition of a case should also
take into account head circumference and parental
concern. Additional studies are needed to address
this issue.
The cases in our cohort were more likely to have
been positioned supine for sleep in the first 6 weeks,
confirming earlier studies that have shown supine
sleeping to be an important determinant for
NSP.
6,11,12,26
The total overall time spent supine in
the first 6 weeks, both awake and asleep, seems also
to be an important predictor. Of interest, the 6-week
cases were also having more upright time, and this
needs additional investigation to determine a rela-
tionship between back and upright time. It is possi-
ble that our question was misinterpreted or that up-
right time is a consequence or predictor of less easy
temperament, which showed up later, in the 4-month
cases. Although we found no significant difference
relating to tummy time in our cohort, it is possible
that our small number of cases was not sufficient to
establish a relationship; however, we have previ-
ously shown that cases are likely to have ⬍5 minutes
a day of tummy time at 6 weeks.
11
In light of all of
the above, we would still recommend that if infants
are sleeping supine, then parents should try to re-
duce the time that their infants spend on their back
during awake time by increasing supervised tummy,
upright, and side-lying play time.
Although others
27,28
have believed that antenatal
influences are strongly related to the later develop-
ment of head deformity, we found no effect of ob-
stetric or socioeconomic factors on the development
of plagiocephaly in our cohort. However, at both 6
weeks and 4 months, cases were more likely to be
those who had an abnormal passive head rotation at
the newborn interview, suggesting either an in utero
or a birth cause for neck tightness, or else asymmetric
neck muscle development in those infants. The num-
bers were small, and not all infants were tested be-
cause to do the test, the infants had to be in a relaxed
state, which was not always possible at the time of
the interview. This result needs confirming in a
larger study. If abnormal head rotation is seen, then
physical therapy could be instituted to prevent pref-
erential positioning as a result.
Cases were less active as judged by their mothers
at 4 months, and this is in accordance with earlier
work in which we have shown that cases had a lower
activity level.
11
We hypothesize that less active in-
fants are more likely to remain lying in the same
position and thus develop a flat spot if there is a
preferred position, particularly if head rotation is
inadequate. Detecting differences in developmental
delay may need a more comprehensive developmen-
tal assessment tool than the PDQ-II. Although there
was a small indication of developmental delay at 6
weeks, we found no difference at 4 months. More
difficult temperament may also be a factor, although
this was significant only on the PAT test and not the
overall temperament rating test. The question re-
978 PLAGIOCEPHALY IN THE FIRST TWO YEARS OF LIFE
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mains as to whether these factors are causative or
resultant of the head deformity.
There are some limitations to this study. Both the
prevalence and the severity of the cases are probably
conservative as a result of mothers’ being highly
aware of head shape by participating in the study
and possibly taking preventive steps to avoid head
flattening. Head shape is a continuous measure rang-
ing from the perfectly symmetrical to the severely
abnormal. The cutoff is somewhat arbitrary and was
used to carry out logistic regression and to establish
ORs for risk factors. The cutoff points of 93% and
106% were derived from a small sample, and prev-
alence rates would be different given different cut-
offs. A receiver-operator characteristic analysis of a
large case-control study would be needed to deter-
mine optimum cutoff points to resolve this issue. We
have opted for a fairly conservative level that we
believe adequately reflects visual assessment of ab-
normality.
Although brachycephaly and plagiocephaly could
have been considered as 2 different outcomes, we
believed that factors for both were similar and that
by excluding brachycephalic cases, they would have
been included with the control infants, thus making
our estimates of ORs falsely conservative.
Some infants varied in and out of abnormal by
being close to the cutoff points, and this in combina-
tion with possible measurement error would explain
those in the NYNY, YNYN and YNNY categories in
Fig 4, although it also possibly reflects that the skull
is still malleable and subject to subtle changes in
shape. We also recognize that we have small num-
bers of cases at 6 weeks and 4 months, and therefore
our case versus control results need to be treated
with caution. Failure to find a significant result may
be attributable to sample size. However, excellent
retention rates enabled us to track the prevalence
through the first 2 years of life, allowing for greater
understanding of the dynamics of head shape devel-
opment as it relates to environmental and other fac-
tors and providing reassurance that the majority of
cases resolve by 2 years of age.
CONCLUSIONS
Head shape varied to a great extent in this group
of normal infants in the first 2 years of life. The first
4 months seems to be an important time for the
initiation of plagiocephaly and brachycephaly. Risk
factors are particularly associated with early limita-
tion of head rotation and early resting positions. A
limitation in neck function should be checked for in
the early weeks and neck motion exercises com-
menced if necessary to encourage full head turning
to both sides. Supine sleeping also plays a major part.
Although it is vital that the supine sleep position be
maintained for SIDS protection, varying the head
position in the first 6 weeks may be important for
plagiocephaly prevention. Not being able to achieve
this should alert parents to the possibility of limited
neck mobility. Infants with lower activity levels may
be more susceptible to developing plagiocephaly.
Although the maximum range of head shape de-
formity was seen at 6 weeks, the greatest point prev-
alence of plagiocephaly in our cohort was seen at 4
months. Almost 30% of the cohort exceeded the cho-
sen cutoffs for classification of cases at some point in
the first 8 months, but most cases improved with
time, leaving a point prevalence of NSP of 3.3% at 2
years.
ACKNOWLEDGMENTS
This study was funded by the Cot Death Association, a division
of the Child Health Research Foundation, Auckland, New Zea-
land. Dr Thompson and Professor Mitchell are supported by the
Child Health Research Foundation. Recruitment of subjects was
made possible by help from the staff at North Shore Hospital and
Birthcare. We thank Melanie Hayes for assistance in data collec-
tion.
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www.pediatrics.org/cgi/content/full/110/6/e72
THE STATUS SYNDROME
“The alarming message here is that status has become a lethal threat. In the
relatively prosperous, industrialized West, Michael Marmot, an epidemiologist at
University College, London, writes, ‘Where you stand in the social hierarchy is
intimately related to your chances of getting ill and your length of life.’ And the
higher your status, the better your prospects....[A]numbing arsenal of facts and
figures serves to show that it is social rank—and not suspiciously similar-sounding
factors like income or education—that makes the crucial difference. There’s the
study of Oscar winners that found they live 4 years longer than their co-stars and
fellow nominees, and the fact that with each mile along the subway line from
downtown Washington to suburban Montgomery County, MD, life expectancy
increases by a year and a half. There is also a mountain of suggestive evidence from
primate research: low-status rhesus macaques with heart disease; low-status ba-
boons with soaring cortisol levels and unwholesome amounts of HDL cholesterol.
It is not our social position per se that does us in, all this implies, but rather the
stress that comes from having less control over our work and lives than people of
higher rank. Not that this is exactly news.”
Eakin E, review of Marmot M. The Status Syndrome. New York Times Book Review. August 22, 2004
Noted by JFL, MD
980 PLAGIOCEPHALY IN THE FIRST TWO YEARS OF LIFE
by on May 20, 2008 www.pediatrics.orgDownloaded from
DOI: 10.1542/peds.2003-0668-F
2004;114;970-980 Pediatrics
B. Lynne Hutchison, Luke A.D. Hutchison, John M.D. Thompson and Ed A. Mitchell
Cohort Study
Plagiocephaly and Brachycephaly in the First Two Years of Life: A Prospective
& Services
Updated Information
http://www.pediatrics.org/cgi/content/full/114/4/970
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