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The objective of this study was to re-evaluate the Caldwell-Moloy (1933) classification of female pelvic shape, which has been traditionally, and still is currently, taught to students of midwifery and medicine. Using modern pelvimetric methodologies and geometric morphometric (GM) analysis techniques, we aim to elucidate whether these classic female pelvic types are an accurate reflection of the real morphometric variation present in the female human pelvis. GM analysis was carried out on sets of pelvic landmarks from scans of women living in a contemporary Western Australian population. Sixty-four anonymous female multi-detector computer tomography (MDCT) scans were used for most of the study and 51 male scans were also examined for comparison. Principle component analysis (PCA) found that there was no obvious clustering into the four distinct types of pelvis (gynaecoid, anthropoid, android and platypelloid) in the Caldwell-Moloy classification, but rather an amorphous, cloudy continuum of shape variation. Until more data is collected to confirm or deny the statistical significance of this shape variation, it is recommended that teachers and authors of midwifery, obstetrics and gynaecological texts be more cautious about continuing to promote the Caldwell-Moloy classification, as our results show no support for the long taught 'four types' of pelvis..
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490 British Journal of Midwifery July 2015 Vol 23, No 7
© 2015 MA Healthcare Ltd
Female pelvic shape: Distinct types
or nebulous cloud?
For well over 50 years, students of midwifery,
obstetrics, gynaecology and related
professions have been taught the Caldwell-
Moloy classification of the female pelvis. While
recognising variation and mixed types, the
current e-book of Mayes’ Midwifery (MacDonald
and Magill-Cuerden, 2011), is typical in its frank
reporting and use of that system. ‘Although there
are four recognised pelvic categories (Caldwell
et al, 1940: Table 24.1), variations within these
categories can occur. Some women may have mixed
features, such as a gynaecoid posterior pelvis and
android fore-pelvis’ (Burden and Simons, 2011:
286). The 10th edition of Clinical Obstetrics also
gives Caldwell-Maloy classification system similar
prominence (Gopalan and Jain, 2005).
The basic ‘four types of pelvis’ categorisation
persists to this day and is evidenced by the fact
that it is taught in many universities and colleges
globally and regularly cited in university-level
midwifery course compulsory texts, such as Mayes
Midwifery (MacDonald and Magill-Cuerden,
2011) and Myles’ Textbook for Midwives (Fraser
and Cooper, 2009) and referred to in recent
studies on female pelvic shape variation (e.g.
Hashemi et al, 2010). The four types of pelvis
categorisation persists even though the initial
simple classification was subsequently extended
by Caldwell et al (1940) to include 14 sub-types,
and that it has also been criticised, for example,
for being overtly racist (Geller and Stockett, 2007).
A recent study of 172 women in a Latvian
population reported a cluster analysis of four
measured diameters of the pelvis; however,
these did not mirror the Caldwell-Moloy (1933)
classification. Using SSPS, the researchers found
three clusters based on an analysis of two linear
measures, the anterio-posterior diameter and
lateral diameters (Kolesova and Vetra, 2012). In
contrast, the 3-D GM analysis of the population
reported in this Western Australia (WA) study
found no such clustering.
This WA study is part of a larger project
analysing pelvic shape for sex estimation in a
forensic context (Franklin et al, 2012a; 2014).
These methods were applied to investigate the
long standing pelvic classification of Caldwell
et al (1940), in order to re-evaluate its biological
foundations. The aim of the study was to elucidate
whether these classic female pelvic types are
an accurate reflection of the real morphometric
variation present in the female human pelvis.
What is the basic classification?
The pelvic shape types in the Caldwell–Moloy
classification will now be defined. These are more
fully described in Caldwell et al (1940).
The four major types are: gynaecoid, android,
anthropoid, and platypelloid (Figure 1). The
gynaecoid (Greek: gyne + eidos = ‘woman type’)
form is the type allocated to the ‘normal’ female
form and has a round or slightly transversally
oval shaped pelvic brim. It has a wide sub-pubic
arch and the sacrum is inclined posteriorly. The
android (Greek: andros + eidos = ‘man type’) form
has the ‘classic’ male, ‘pear shaped’ brim with the
widest transverse diameter at the brim, closer to
the sacrum than the pubis. The sub-pubic arch is
narrow, the sacrum is inclined anteriorly and the
cavity is funnel shaped with prominent ischial
The objective of this study was to re-evaluate the Caldwell-Moloy (1933)
classification of female pelvic shape, which has been traditionally, and still
is currently, taught to students of midwifery and medicine. Using modern
pelvimetric methodologies and geometric morphometric (GM) analysis
techniques, we aim to elucidate whether these classic female pelvic types
are an accurate reflection of the real morphometric variation present in
the female human pelvis.
GM analysis was carried out on sets of pelvic landmarks from scans
of women living in a contemporary Western Australian population. Sixty-
four anonymous female multi-detector computer tomography (MDCT)
scans were used for most of the study and 51 male scans were also
examined for comparison.
Principle component analysis (PCA) found that there was no obvious
clustering into the four distinct types of pelvis (gynaecoid, anthropoid,
android and platypelloid) in the Caldwell-Moloy classification, but rather
an amorphous, cloudy continuum of shape variation.
Until more data is collected to confirm or deny the statistical
significance of this shape variation, it is recommended that teachers
and authors of midwifery, obstetrics and gynaecological texts be more
cautious about continuing to promote the Caldwell-Moloy classification,
as our results show no support for the long taught ‘four types’ of pelvis.
Keywords: Female pelvic shape, Caldwell and Moloy, Geometric
morphometric analysis
Algis Kuliukas
PhD Candidate
University of Western
Lesley Kuliukas
Midwifery Lecturer
Curtin University Western
Daniel Franklin
Director and Associate
University of Western
Ambika Flavel
Research Associate
University of Western
British Journal of Midwifery July 2015 Vol 23, No 7
© 2015 MA Healthcare Ltd
Following this, each anterior type could
theoretically be combined with any of the four
posterior types, yielding 16 possible types and,
assuming the same number of permutations could
exist for both the inferior and posterior aspects of
the pelvis, there could be as many as 256 subtypes
in total.
However, Caldwell et al (1940) chose not to
include a distinction between inferior and superior
aspects in their subtype classification and decided
that it was impossible for the anthropoid segment
spines. Anthropoid, despite its name (Greek:
anthropos = ‘human’), denotes a more ape-like
shape, where the anterior-posterior (AP) diameter
at the brim is significantly larger than the lateral,
giving a long narrow oval shape. Finally, the
Platypelloid (Greek: platys + eidos = ‘flat type’)
form is where the lateral diameter at the brim
is significantly larger than the AP, giving a flat
or transversally oval form (Caldwell et al, 1940;
Burden and Simons, 2011).
Caldwell and Moloy (1938) found that the
gynaecoid form was the most common among
women, with around 42% of the populations
studied having this type. In their study, ‘White’
and ‘African American’ females were published
separately—in Figure 1, they are combined.
How was the basic classification
Caldwell and Moloy (1938) and Caldwell et al
(1940) extended their classification. In addition
to the four ‘classic’ or ‘pure’ types, it was decided
that combinations (‘mixed’ types) were not only
possible, but actually more likely. They describe
‘departures’ where the classic form at the pelvic
inlet differs from that below it. For example, a
classic gynaecoid laterally oval pelvic brim shape,
may be reclassified ‘mixed’ if they also exhibit a
narrow sub-pubic arch, an anteriorly tilted sacrum
or narrower sciatic notch (Caldwell et al, 1940).
Other ‘mixed’ types were also reported where the
anterior section of the true pelvis differs from the
posterior segment. These became the basis for the
enhanced classification, where the parent type of
the posterior segment is combined with the parent
type of the anterior—e.g. a pelvis with a male-like
sacrum inclination and diminished sciatic notch
but with a wide sub-pubic angle would be termed
‘android-gynaecoid’ (Table 1).
Figure 1. The basic Caldwell-Moloy classification and reported prevalence (adapted
from Caldwell et al, 1940, data from US population. Black and White populations were
reported originally, combined here)
Table 1. Caldwell-Moloy subtypes, comments and numbering system
Posterior segment type
Gynaecoid Anthropoid Android Platypelloid
Anterior segment type
Gynaecoid True gynaecoid
(4, normal female pelvis)
Anthropoid Gynaecoid-anthropoid
True anthropoid
(1, transversally contracted
(not included)
Android Gynaecoid-android
(6, gynaecoid with
narrow front pelvis)
(3, anthropoid with narrow
fore pelvis)
True android
(8, masculine type,
funnel type)
Platypelloid Gynaecoid-flat
(not included)
True platypelloid
From: Caldwell et al (1940)
492 British Journal of Midwifery July 2015 Vol 23, No 7
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position equally and the flat sides and large anterior
posterior diameter to the outlet allows the fetus to
descend without rotation; therefore, the baby may
be born in a persistent occipito-posterior position
(Burden and Simons, 2011). A platypelloid pelvis
would encourage engagement in the occipito-lateral
position and is more likely to cause asynclitism in
labour as one parietal bone enters the pelvis before
the other. The android and platypelloid pelvis types
are most likely to cause obstruction (Burden and
Simons, 2011).
The clinical rationale for categorising pelves was
to be able to predict these various mechanisms
of labour and the possibility of cephalopelvic
disproportion (Caldwell and Moloy, 1933). However,
over time, it became apparent that theoretical
pelvic shapes do not necessarily determine labour
outcomes. It is virtually impossible to predict
birth outcomes before labour even starts (Hanzal
et al, 1993; Spörri et al, 2002). The need for
pelvic categorisation was therefore questioned
from a practical obstetric point of view, yet the
classification is still described in current textbooks
for midwives and obstetricians (Gopalan, 2005;
Fraser and Cooper, 2009; MacDonald and Magill-
Cuerden, 2011).
Potential racist criticisms of the
Caldwell-Moloy classification
Caldwell and Moloy wrote many statements that can
potentially be perceived as racist today. For example,
the populations that the authors linked more closely
to the ‘anthropoid’ pelvis are characterised as
‘primitive races’ (Caldwell and Moloy, 1938: 5). Since
then a number of fossil pelves (e.g. Australopithecus
afarensis; Tague and Lovejoy, 1986) have been
found, attributed to putative hominin ancestors,
which are distinctly platypelloid in shape, a form
that Caldwell and Moloy described as ultra-human
and not intermediate between humans and the
great apes in shape (Australopithecus africanus;
Zuckerman et al, 1973).
New morphological approaches
Although some of the X-ray imaging methods
used by Caldwell and Moloy to identify the shapes
of female pelves were innovative in their time,
the original basis of the ‘four type’ classification
was simply observational. Various measurements
taken of ratios and angles of selected pelvic
landmarks were used to help classify pelves, but
the decision was always, in the end, one based on
a subjective assessment.
More sophisticated techniques of shape analysis
are available today. For example, landmark-based
GM methods have been successfully employed
to combine with a platypelloid one in either of the
two combinations (Caldwell et al, 1940), resulting
in just 14 subtypes as outlined in Table 1.
It was proposed that ‘borderline types’ of pelvis
can be described by using these combinations
(Caldwell and Moloy, 1938), but there appears to
be little consideration that there may be a smooth
continuum of shapes from one type to the next,
within each segment type itself.
Sixty years of the Caldwell-Moloy
classification in midwifery,
obstetrics and gynaecology
Exactly when the Caldwell-Moloy classification of
the female pelvis became widely adopted as a
standard in the teaching of midwifery and medicine
is open to debate, but there seems little doubt that
by the 1950s it was already well established. Medical
and midwifery textbooks in the 1970s and 1980s
continued to categorise pelves in that way (Beischer
and Mackay, 1979; Bennett et al, 1989) and suggested
that the type of pelvis determined the passage of
the fetus during birth: ‘These differences in pelvic
shape are of more than radiological interest, since
they determine, in large measure, the mechanism
which is adopted by the fetus in passing through the
birth canal. (Beischer and Mackay 1979: 23). This
general assumption associated different types of
pelves with different mechanisms of labour because
of the differences within the true pelvis. This is
important because as Burden and Simons (2011:
286), in MacDonald and Magill-Cuerden point out,
‘the most important factor is the true pelvic space
available for the fetus to descend and emerge from
the pelvis during labour.
The ideal pelvis for childbirth allows the fetus to
engage in the transverse position due to the wide
transverse diameter at the brim, rotate mid-cavity
at the level of the pelvic floor as this plane of the
pelvis is circular and then birth in an occipito-
anterior position taking advantage of the long
anterio-posterior diameter at the pelvic outlet.
Pelves of different shapes are considered to affect
the labour in different ways. The android pelvis,
because of having more space posteriorly at the
brim, is considered to increase the likelihood of
an occipito-posterior engagement of the head
(Burden and Simons, 2011). The fetus may remain
posterior through labour or may become impinged
on the prominent diameter between the ischial
spines ischial spines during the rotation mid-cavity,
causing a deep transverse arrest necessitating birth
by rotational forceps or caesarean section. The
anthropoid pelvis, with its long anterio-posterior
oval shaped brim causes the fetus to engage in
either the occipito-anterior or occipito-posterior
British Journal of Midwifery July 2015 Vol 23, No 7
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for several years in various studies in physical
anthropology, palaeoanthropology and forensic
science, and have been shown to elucidate novel
morphometric features not readily described using
simple linear measurements (Franklin et al, 2014).
Rather than simply using ‘traditional’ ratios (e.g.
lateral pelvic diameter divided by anterio-posterio
pelvic diameter) and angles (e.g. sub-pubic)
to attempt to classify pelves, large groups
of homologous landmarks can be captured as
discrete 3-D (x, y, z) co-ordinates, stored, rendered
graphically and then statistically analysed, all
using sophisticated modern computer software.
Baab et al (2012) summarise these GM
techniques and some of their recent uses in
physical anthropology. They describe how, in
theory, GM methods mathematically describe the
whole shape of the specimens of interest so that
they may be evaluated objectively and statistically.
Their paper focuses on studies of the human skull,
but the greater shape variation in the human pelvis
(especially between the sexes) supports that these
techniques should yield potentially even more
valuable and clinically useful insights, as we hope
to show here.
The uncertainty surrounding the Caldwell
and Moloy classification provides an excellent
opportunity for the application of these methods.
In particular, the true pelvis, including features of
the pelvic brim, such as the sacral promontory;
mid-cavity, such as the subpubic arch and outlet,
such as the ischial spines, can be statistically
quantified using a relatively novel technique
in GM—semi-landmarks. Even the shape and
curvature of featureless regions of bone can be
traced using homologous sets of 3-D landmarks.
Following in the footsteps of Caldwell and
Moloy’s pioneering research, this study is also
based on the analysis of a living population of
females (and, for comparison, some males) taken
from a contemporary WA population, rather
than temporally and geographically removed
skeletal collections. Rather than using the fixed,
two-dimensional X-ray images that were taken
by Caldwell et al (1940) in postnatal women,
the present study analyses dynamic, 3-D images
generated from computer tomographic (CT) scans
using the image rendering program, Osirix™.
If the Caldwell and Moloy Classification is
morphologically accurate, there should be
discernible clustering patterns visible when 3-D
GM data of female pelves are statistically analysed
in Morphologika. Specifically, there should be
four significant groups corresponding to their
four ‘types’ of pelvis when individual morphs are
plotted against the major principal components.
Computer tomographic scans as a source
for pelvimetric population data
The Centre for Forensic Science at the University
of Western Australia (UWA) has been developing
techniques for acquiring 3-D landmarks in CT
scanned images. These techniques have been
applied in studies of various parts of skeletal
anatomy and results have been verified against
traditional measurement methods (Franklin et al,
2012a; 2012b; 2014).
CT scans are specifically well-suited to skeletal
biological research as the post-cranial skeleton
can be filtered out from the rest of the scanned
tissue with a high degree of resolution. The scans
assessed typically have a 1 mm slice thickness, the
visualisation of the regional skeletal anatomy is
therefore performed at a much higher level than
that of the X-rays used by Caldwell et al (1940).
Sample demographics
This study quantifies measurements from CT
scans from 64 women currently residing in WA.
A sample of individuals was randomly selected
from the WA Department of Health (DH)
Picture Archiving and Communication System
(PACS) database, and consists of adult patients
presenting at various hospitals during 2010–2011.
The scans were anonymous when received by
the authors with only sex and age data retained.
The mean age of the males was 47 years (range
22–63), and 44 (range 18–63) for the females.
Sample demographics are described in Table 2.
While undoubtedly comprising various ethnic
backgrounds characterised in the general WA
population, the sample is predominantly
Caucasian which typified the WA population.
Only individuals without obvious congenital or
acquired pelvic pathology were included.
Ethical approval
Ethical research approval was granted by the
Human Research Ethics Committee of the
University of Western Australia (RA/4/1/4362).
Landmark schema
Pelvic shapes were recorded using a defined set of
77 landmarks designed to represent homologous
bony features, these are used to generate semi-
landmarks that trace a further 150 relative smooth
and featureless curves and surfaces, making 228
landmarks in total. In addition, to point type
landmarks, taken from relatively easily-identifiable
494 British Journal of Midwifery July 2015 Vol 23, No 7
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These data are then downloaded and processed in a
custom-built database package.
3-D GM analysis with Morphologika
Prior to analysis, the landmarks obtained for
each specimen needed to be put into a common
co-ordinate system where all morph entities were
standardised for size and orientation leaving
relative variation purely to shape. Then, a PCA was
performed, which determines the key principal
components, which discriminate the pelves on
shape. Morphologika can then plot the individual
morphs against two axes, representing two principal
components, at a time. Using this method, most
of the shape variation in a set of morphs can be
visualised and explored. Morphologika displays
the landmarks with, or without, a wireframe to link
them (Figure 3) allowing them to be rotated and the
shape variation to be explored against the principal
components being analysed.
Anterio-posterior/lateral diameter ratio
cluster analysis
Following the Kolesova and Vetra (2012) study,
which found some clustering in their analysis of
anterio-posterior/lateral diameter ratios, these
measures and their ratios were extracted from this
data set for analysis. Generally, the range of ratios
ran smoothly from rather platypelloid (anterio-
posterior 83.4% of lateral) to rather anthropoid
(anterio-posterior 113% of lateral) in 63 of the 64
individuals. With the exception of one woman that
was markedly anthropoid at anterio-posterior 146%
of lateral, there were no significant clusters of data.
Female only
The PCA of the 64 female pelves revealed that
13% of the variation was accounted for by the first
principal component, 47% by the first six. No
obvious clustering patterns were visible in any
of the 15 pairwise comparisons of the top four
principal components (Figures 4 and 5).
Subjective assessment of female-only data
From the female-only data there is no obvious
clustering of points into four distinct shape
types so it was decided to add to the dataset
one of the four ‘type specimen’ in the Caldwell-
Moloy specification—the android (or ‘male’)
type. According to the traditional classification,
approximately 25% of female pelves should fall into
this category.
Males included
The sample was then analysed with male pelves
Table 2. Demographics
of participants
Age range Females Males
18–20 2 0
21–30 7 6
31–40 10 7
41–50 24 19
51–60 18 17
61–70 3 2
Total 64 51
Figure 2. Screen shot demonstrating semi-landmark
placement in OsirixTM
points on the pelvis, the shape of a series of
significant curvatures of bone, that are relatively
featureless, were also captured for analysis via
Each semi-landmark set is defined by a point
type landmark to demarcate its start and end point
as well as the number of landmarks to be generated
along the curvature of bone (Figure 2). The semi-
landmark co-ordinates were generated by an
in-house developed database application, MorphDb.
Osirix™ data capture
Data are collected using the open source DICOM
(digital imaging and communications in medicine)
software package, Osirix™. The software allows the
DICOM file data to be filtered by the density of the
voxels (3-D pixels) so that only skeletal structures
are visible. The objects are thus rendered as 3-D
objects that can be rotated and zoomed in or out.
Osirix™ allows the placement of landmarks onto
the surface of the rendered image, each of which
captures the (x, y, z) co-ordinates of the point.
British Journal of Midwifery July 2015 Vol 23, No 7
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included. If the Caldwell-Moloy android type of
female pelvis was found among this population, one
would expect to see some overlap with, or at least
a distinct grouping close to, the male distribution.
As shown in Figure 6, female and male and
pelvis shapes do not overlap at all when compared
by the most discriminatory principle component
PC1, and there is no distinct group of females that
appears in close proximity to the male group.
Historically, students of midwifery and medicine
have been taught that women will have either a
gynaecoid, android, anthropoid or platypelloid
pelvis. The results of this WA study did not reflect
the current taught concept that there are four
distinct type of pelvis. Rather than falling into
specific categories, the pelves formed a nebulous
cloud of variation. Furthermore, the concept of
25% of women having an android, or male shaped,
pelvis was refuted. In this study, the analysis of
both male and female pelves clearly demonstrated
two distinct groups with no overlap, suggesting
that the android shape occurs in women very
rarely, if at all.
The limitation of this study was that the sample
size was small and geographically specific. A
greatly expanded study, in terms of number and
geographical origin, would be required to address
this issue.
This study is preliminary in nature but appears
to provide sufficient evidence to cast doubts on
the Caldwell et al classification. These findings
suggest that it would be worthwhile to reconsider
the traditional teaching of midwifery, medical
and related professions that there are four distinct
types of female pelvis and, instead, encourage
Figure 3. Pelvis using semi-landmarks rendered without (and with) a wireframe
Table 3. Principal components
analysis of female pelves
component (PC)
Individual Cumulative
PC-1 0.129 0.129
PC-2 0.104 0.232
PC-3 0.083 0.315
PC-4 0.057 0.372
PC-5 0.054 0.426
PC-6 0.046 0.471
Figure 4. PC-1 x PC-2 (Female only)
(Pelvic images give indication of the shape
differences at the extremes of the principle
the concept that the shape variation is simply
characterised by a cloudy continuum.
The key argument of this paper is to question
the traditional midwifery teaching that a woman’s
pelvis can be pigeon-holed, by its shape, into one
of four categories. Complex physical traits, such as
body height and the morphology of major skeletal
structures, are doubtless under the genetic control
of several alleles and many environmental and
496 British Journal of Midwifery July 2015 Vol 23, No 7
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Key points
lWomen’s pelves may not be definable as one of the four types as
described by Caldwell and Moloy
lThe male pelvis (android) is distinct from the female pelvis
Figure 5. PC-3 x PC-4 (Female only)
(Pelvic images give indication of the shape
differences at the extremes of the principle
Figure 6. PC-1 v PC-2 male and female. No
significant group of females overlap with, or even
cluster close to the male as one would predict if
there was an ‘android’ type of female pelvis
epigenetic factors. This type of control predicts
that any statistical analysis of related measures
will follow a smooth continuum in a normal
distribution as seen, for example, with body height.
Our results support the expectation that such a
smooth distribution of shapes exist in the pelvis.
Rather than trying to determine which distinct
type of pelvis a woman has, we argue that it is
more helpful to simply have an awareness that
pelvic shape has many components that may
affect childbirth, each of which can vary smoothly.
Certain phenomena, such as a high head at term
or deep transverse arrest, could be due to a more
exaggerated oval shaped brim or more prominent
ischial spines; to attempt to explain such events by
categorising the pelvis is not necessary and will not
affect the management of labour. BJM
Acknowledgements: The authors would like to thank over
100 anonymous people of Western Australia who agreed to
allow their MDCT scans to be used in scientific research.
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33: 71–165
... Rare types (i.e., non-gynaecoid types) are supposed to be associated with a higher frequency of forceps delivery and cesarean section (2). However, recent studies have questioned this morphologic classification based on four pelvic patterns (5,6). Kuliukas et al. (5) used principle component analyses (PCAs) and found an amorphous, cloudy continuum of female pelvic shape variation. ...
... The results of this study did not support the previous classification described by Cadwell and Moloy in 1933 (2), which is in line with the most recent studies (5,6). Among all the factors considered in this research, birthplace was the only effective factor that played a role in pelvic shape. ...
... The pelvic shape variability of our samples was not explained by the four categories previously proposed by Cadwell and Moloy (2). Our results are consistent with the findings obtained by Kuliukas et al. (5). Based on our results, midwifery teachers are recommended to be more cautious about adherence to the classification of Cadwell and Moloy (2). ...
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Background & aim: Pelvic shape has important effects on obstetrical outcomes. Therefore, this study aimed to determine the etiologic factors that contribute to the formation of female pelvis and describe its variability. Methods: This study was conducted on 131 women referring to Saint Joseph Hospital, Marseille, France, from March 29, 2011, to December 10, 2013. These women underwent a pelvic scan, and then completed a questionnaire to assess their exposure to several environmental influences, including adolescent physical activity, mode of acquiring an erect posture, diet, birthplace, socioeconomic status, presence of a spinal disorder, and age. A total of 43 pelvic variables were measured. Pelvic variability was analysed using principal component analyses (PCAs). Only the first two components of the PCA were analysed in this study. Results: Based on our results, the age of acquisition of erect posture was not associated with any pattern of pelvic variability. In addition, diet found to have no effect on the inlet shape. Spinal disorders, age, and physical activities did not exert any impact on pelvic shape. Geographic origin was found to be the only factor related to specific pelvic shape patterns. Conclusion: The pelvic shape variability of our study population was not explained by the four categories previously proposed by Cadwell and Moloy in 1933. It is recommended that midwife teachers should be more cautious about adherence to this classification. Geographic origin seemed to be related to different pelvic shape patterns, suggesting the effect of the neutral population history in pelvic variability.
... In the 1930s, Caldwell and Moloy published a series of influential papers that categorized the female pelvis into four primary shapes (platypelloid, gynecoid, anthropoid and android) based on the shape of the pelvic inlet [47][48][49] (Supplementary Fig. 1). All of these classifications were heavily influenced by 'racial' typologies [39,50], and might justifiably be considered historic were they not still reiterated in medical textbooks even to the present day [51][52][53][54]. ...
... They suggested this is due to genetic drift following human migrations out of Africa where variability appears to have been higher. In contrast, Kuliukas et al. [51] used computer tomography to characterize the pelves of 64 women from Western Australia concluding that the resulting variation may be due to a variety of epigenetic and developmental factors. ...
Childbirth is commonly viewed as difficult in human females, encompassed by the “Obstetrical Dilemma” (OD) described by early palaeoanthropologists as an evolved trade-off between a narrow pelvis necessitated by bipedalism and a large-brained fetal head. The OD has been challenged on several grounds. We add to these challenges by suggesting humans likely squatted regularly during routine tasks prior to the advent of farming societies and use of seats. We suggest that habitual squatting, together with taller stature and better nutrition of ancestral hunter-gatherers compared with later Neolithic and industrial counterparts, obviated an OD. Instead, difficulties with parturition may have arisen much later in our history, accompanying permanent settlements, poorer nutrition, greater infectious disease loads and negligible squatting in daily life. We discuss bioarchaeological and contemporary data that support these viewpoints, suggest ways in which this hypothesis might be tested further, and consider its implications for obstetrical practice. Lay Summary Human childbirth is viewed as universally difficult. Evidence from physical therapies/engineering, and studies of living and ancestral humans illustrates habitual squatting widens the pelvis and could improve childbirth outcomes. Obstetrical difficulties emerged late in prehistory accompanying settled agriculture, poorer nutrition and less squatting. Specific physical exercises could improve obstetrical practice.
... [31]. The majority of recent research undertaken has focussed on living individuals, using advanced technologies to improve our understanding of age and sex estimation [32][33][34][35][36]. ...
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The aim of this brief critical qualitative analysis is to examine the development of forensic anthropology in Australia, at a time of significant change in the discipline. It will briefly summarise its historical establishment, making comparative reference to other regions— particularly the United Kingdom and United States, and the influence of the Bali Bombings of 2002, Indian Ocean earthquake and tsunami of 2004 and Black Saturday Bushfires of 2009. The analysis goes on to consider key factors in research in forensic anthropology in the United States, and the development of standards and regulation in the US and UK. The significance of research in post-mortem diagenesis in Brazil—a country sharing aspects of climate, soil types and demography with Australia—is also considered, as well as the significance of patterns of casework encountered in Australia compared with those of other jurisdictions. While forensic anthropology as a discipline has grown remarkably in recent years, this analysis suggests that research and training tailored to the specific pattern of casework encountered in Australia is now essential to support the development of national standards in science, education, and professional regulation. The significance of the establishment of the first taphonomy research facility outside of the US—the Australian Facility for Taphonomic Experimental Research—is briefly considered with reference to what this facility may offer to the development of forensic anthropology in Australia.
... And further, this categorization disregards the apparent morphological variation of pelvic inlet shape. Recent analyses by Kuliukas et al. (2015) further support the problematic nature of using pelvic typology; they demonstrated, through PCA, that female pelvic shape of a contemporary Western Australian population does not fall into four distinct categories but rather demonstrates a continuum of shape variation. ...
It is well known that there are significant differences in the pelves of males and females due, in part, to differing constraints. The male and female pelves must be suitable for upright posture and locomotion, but the female pelvis must also be suitable for reproduction. These differing requirements lead to differences in the shape and size of various pelvic dimensions. These differences are reflected in the pelvic inlet, midplane, and outlet. Current research has documented dimorphisms in the posterior and anterior spaces in all three of these planes. One measure however, that is calculated from the relationship between the length of the anterior?posterior diameter (APD) and the transverse diameter (TD) of the inlet, is not as dimorphic as previously suggested. This computed value is used to describe four main categories of inlet shape: android, gynecoid, anthropoid, and platypelloid. Current textbooks in anatomy and midwifery describe these forms and identify the typical male inlet shape as android and the typical female inlet shape as gynecoid. In this study, however, using skeletonized pelves of 378 adult individuals from three identified skeletal collections, the most common inlet shape for both males and females was android. In addition, when examining shape as a continuous variable, inlet shape is not sexually dimorphic in two of the three populations examined in this study. Based on the results of this study, the inlet shape for males and females is less dimorphic than previously thought, and we need to discontinue using pelvic categories to describe typical inlet shape. Anat Rec, 300:706?715, 2017.
... Several publications in this field demonstrate that virtual modalities lend themselves naturally to this application. [141][142][143][144][145][146][147][148] Biologically homologous skeletal landmarks on skeletal elements have been used to calculate linear measurements, angles, subtenses and indices since the end of the 19th 149 and early 20th centuries [150][151][152] and continue in the modern era. 153,154 The use of landmarks for geometric morphometric analysis is comparatively recent, with Bookstein 155 leading developments in statistical assessment of biological shape variation. ...
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Technological advancements in forensic imaging have had tremendous flow-on benefits to the professional practice of forensic anthropology, not only in respect of case-work analyses, but in facilitating empirical research that has validated and/or improved existing, and introduced novel, methods into the discipline. Some of the pioneering practical examples of radiographic imaging being applied in the forensic analysis of human skeletal remains date to the initial introduction of radiography in the late 19th and early 20th centuries. Subsequent modern applications have developed concurrent to the use of computed tomography in the forensic morgue for autopsy procedures by pathologists; virtopsy (as it is now termed) represents a powerful non-invasive supplement/alternative to traditional autopsy practices where dissection may not be allowable due to religious objection (amongst other reasons). The present review considers a brief history of skeletal radiographic imaging and the specific modalities typically employed. Forensic applications of ‘virtual anthropology’ are then discussed, as are applications of the latter in DVI and other case-work scenarios. Throughout the review we emphasise the research importance of virtual modelling and conclude with some thoughts for future directions.
The birthing process in modern humans is supposed to be different from non-human primate birth. In humans the foetal head exits the birth canal mostly in occiput anterior position and the pregnant woman frequently seeks assistance. These characteristics have been interpreted from an evolutionary perspective and they are supposed to be due to the physical constraints related to the increase in brain size and bipedal locomotion. In this study, we analyse a close-up video recording of the delivery of a female Pan troglodytes from the Réserve africaine de Sigean (France). Our aim is to check whether the human birth characteristics are absent in this case. We observe a human-like occiput anterior position at the expulsion with a manual deflexion of the foetal head performed by the mother herself. There are neither restitution movements nor perineal tears. Our observation, together with the three others cases of occiput anterior positions described in the literature, leads us to question the evolutionary hypotheses related to human birth. However, more videos of Pan troglodytes birth are needed to investigate the diversity of the foetal head position during expulsion.
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Due to the fragmentary condition of most specimens, there have been few studies on the anatomy of the early hominid bony birth canal. However, recovery of an innominate and sacrum from one individual (A.L. 288-1, Australopithecus afarensis) allows reconstruction of the complete pelvis. Although A.L. 288-1 is considered to have been a female, several morphologies of its true pelvis resemble those of human males, such as sacral angulation, ischiopubic ramus and, principally, funnelling of the pelvic cavity. The implication is that some of the pelvic dimorphisms characteristic of modern Homo sapiens developed subsequent to the emergence of bipedalism. The shape of A.L. 288-l's true pelvis is compared with that of female H. sapiens and Pan troglodytes. A.L. 288-l's pelvis is platypelloid, unlike Homo and Pan. The obstetric consequence of the difference in pelvic shape would have been a unique mechanism of birth in A.L. 288-1, with the fetus being born along the transverse axis of the outlet. Rotation of the fetal cranium within the pelvic canal, a characteristic of human birth, would not have occurred in A.L. 288-1. The platypelloid (false and true) pelvis of A.L. 288-1 is related to the requirements of locomotion and visceral accommodation and support. Although the obstetric analysis indicates that birth might have been slow and difficult in A.L. 288-1, we do not consider there to have been selection for the australopithecine fetus to have been born in a more altricial state than that in pongids. However, exactly when secondary altriciality, which is a characteristic of modern humans, emerged is a current subject of debate.
Obstetrics and the newborn gives as a textbook a short and concise survey of the whole area of obstetrics from the time of conception to childbirth. It deals with the physiological facets as well as the pathological events. A separate chapter is devoted to each subject. The neonate is dealt with separately, the routine, immediate post partum a well as the pathological aspects. The whole work is clarified by photographs and schematic drawings. The separate chapter on family planning as well as the chapter on examination questions with answers are notable.
Requisite to routine casework involving unidentified skeletal remains is the formulation of an accurate biological profile, including sex estimation. Choice of method(s) is invariably related to preservation and by association, available bones. It is vital that the method applied affords statistical quantification of accuracy rates and predictive confidence so that evidentiary requirements for legal submission are satisfied. Achieving the latter necessitates the application of contemporary population-specific standards. This study examines skeletal pelvic dimorphism in contemporary Western Australian individuals to quantify the accuracy of using pelvic measurements to estimate sex and to formulate a series of morphometric standards. The sample comprises pelvic multi-slice computer tomography (MSCT) scans from 200 male and 200 female adults. Following 3D rendering, the 3D coordinates of 24 landmarks are acquired using OsiriX® (v.4.1.1) with 12 inter-landmark linear measurements and two angles acquired using MorphDb. Measurements are analysed using basic descriptive statistics and discriminant functions analyses employing jackknife validation of classification results. All except two linear measurements are dimorphic with sex differences explaining up to 65 % of sample variance. Transverse pelvic outlet and subpubic angle contribute most significantly to sex discrimination with accuracy rates between 100 % (complete pelvis-10 variables) and 81.2 % (ischial length). This study represents the initial forensic research into pelvic sexual dimorphism in a Western Australian population. Given these methods, we conclude that this highly dimorphic bone can be used to classify sex with a high degree of expected accuracy.
It is widely accepted that the most accurate statistical estimations of biological attributes in the human skeleton (e.g., sex, age and stature) are produced using population-specific standards. As we previously demonstrated that the application of foreign standards to Western Australian individuals results in an unacceptably large sex bias (females frequently misclassified), the need for population-specific standards is duly required and greatly overdue. We report here on the first morphometric cranial sexing standards formulated specifically for application in, and based on the statistical analysis of, contemporary Western Australian individuals. The primary aim is to investigate the nature of cranial sexual dimorphism in this population and outline a series of statistically robust standards suitable for estimating sex in the complete bone and/or associated diagnostic fragments. The sample analysed comprised multi-detector computed tomography cranial scans of 400 individuals equally distributed by sex. Following 3D volume rendering, 31 landmarks were acquired using OsiriX(®), from which a total of 18 linear inter-landmark measurements were calculated. Measurements were analysed using basic descriptive statistics and discriminant function analyses employing jackknife validations of classification results. All measurements (except frontal breadth and orbital height - Bonferroni corrected) are sexually dimorphic with sex differences explaining 3.5-48.9% of sample variance. Bizygomatic breadth and maximum length of the cranium and the cranial base contribute most significantly to sex discrimination; the maximum classification accuracy was 90%, with a -2.1% sex-bias. We conclude that the cranium is both highly dimorphic and a reliable bone for estimating sex in Western Australian individuals.
Study of morphological form is fundamental to the discipline of paleoanthropology. The size and shape of our ancestors' anatomical features have long been the focus of research on hominin systematics, phylogeny, functional morphology, ontogeny, variation, and evolutionary change. Early physical anthropologists relied on both qualitative descriptions of anatomical shape and linear measurements to assess variation among hominins. The seminal works of W. W. Howells and C. E. Oxnard helped to bring multivariate techniques to the forefront of physical anthropology. Howells' intention was the objective delineation of components of shape, which could then fuel further analyses and interpretations, as well as clarification of the ways that growth influences interindividual and interpopulational differences in shape. He expressed concern that previous comparisons of individual measurements did not capture the overall shape of the skull, which is "expressed by the relations between measurements." Similarly, Oxnard recognized that a multivariate approach to the study of complex shapes allows "for such perturbations (e.g., variation and covariation)…that are difficult to evaluate by eye and impossible to reveal by measurement and simple analysis alone." While multivariate methods offered clear advantages over univariate or bivariate representations of shape, the analysis of traditional morphometric measures such as linear distances, angles, and ratios, has limitations when it comes to quantifying the complex geometry of some anatomical structures.
A current limitation of forensic practice in Western Australia is a lack of contemporary population-specific standards for biological profiling; this directly relates to the unavailability of documented human skeletal collections. With rapidly advancing technology, however, it is now possible to acquire accurate skeletal measurements from 3D scans contained in medical databases. The purpose of the present study, therefore, is to explore the accuracy of using cranial form to predict sex in adult Australians. Both traditional and geometric morphometric methods are applied to data derived from 3D landmarks acquired in CT-reconstructed crania. The sample comprises multi-detector computed tomography scans of 200 adult individuals; following 3D volume rendering, 46 anatomical landmarks are acquired using OsiriX (version 3.9). Centroid size and shape (first 20 PCs of the Procrustes coordinates) and the inter-landmark (ILD) distances between all possible pairs of landmarks are then calculated. Sex classification effectiveness of the 3D multivariate descriptors of size and shape and selected ILD measurements are assessed and compared; robustness of findings is explored using resampling statistics. Cranial shape and size and the ILD measurements are sexually dimorphic and explain 3.2 to 54.3 % of sample variance; sex classification accuracy is 83.5-88.0 %. Sex estimation using 3D shape appears to have some advantages compared to approaches using size measurements. We have, however, identified a simple and biologically meaningful single non-traditional linear measurement (glabella-zygion) that classifies Western Australian individuals according to sex with a high degree of expected accuracy (87.5-88 %).
In Australia, particularly Western Australia, there is a relative paucity of contemporary population-specific morphometric standards for the estimation of sex from unknown skeletal remains. This is largely a historical artefact from lacking, or poorly documented, repositories of human skeletons available for study. However, medical scans, e.g. MSCT (multislice spiral computed tomography) are an ingenious and practical alternative source for contemporary data. To that end, this study is a comprehensive analysis of sternal sexual dimorphism in a sample of modern Western Australian (WA) individuals with a main purpose to develop a series of statistically robust standards for the estimation of sex. The sample comprises thoracic MSCT scans, with a mean of 0.9 millimeter (mm) slice thickness, on 187 non-pathological sterna. Following 3D volume rendering, 10 anatomical landmarks were acquired using OsiriX(®) (version 3.9) and a total of 8 inter landmark linear measurements were calculated using Morph Db (an in-house developed database application). Measurements were analyzed using basic descriptive statistics and discriminant function analyses, with statistical analyses performed using SPSS 19.0. All measurements are sexually dimorphic and sex differences explain 9.8-47.4% of sample variance. The combined length of the manubrium and body, sternal body length, manubrium width, and corpus sterni width at first sternebra contribute significantly to sex discrimination and yield the smallest sex-biases. Cross-validated classification accuracies, i.e., univariate, stepwise and direct function, are 72.2-84.5%, with a sex bias of less than 5%. We conclude that the sternum is a reliable element for sex estimation among Western Australians.