BMJ Open. 2018 (Jul 25); 8 (7): e021378 ~ FULL TEXT
Stefan Malmqvist, Inger Kjaermann, Knut Andersen, Anne Marie Gausel, Inger Økland, Jan Petter Larsen, Kolbjorn S Bronnick
The Norwegian Centre for Movement Disorders,
Stavanger University Hospital,
OBJECTIVE: To explore if pregnant women with pelvic girdle pain (PGP), subgrouped following the results from two clinical tests with high validity and reliability, differ in demographic characteristics and weekly amount of days with bothersome symptoms through the second half of pregnancy.
DESIGN: A prospective longitudinal cohort study.
PARTICIPANTS: Pregnant women with pelvic and lumbopelvic pain due for their second-trimester routine ultrasound examination.
SETTING: Obstetric outpatient clinic at Stavanger University Hospital, Norway.
METHODS: Women reporting pelvic and lumbopelvic pain completed a questionnaire on demographic and clinical features. They were clinically examined following a test procedure recommended in the European guidelines for the diagnosis and treatment of PGP. Women without pain symptoms completed a questionnaire on demographic data. All women were followed weekly through an SMS-Track survey until delivery.
PRIMARY AND SECONDARY OUTCOME MEASURES: The outcome measures were the results from clinical diagnostic tests for PGP and the number of days per week with bothersome pelvic pain.
RESULTS: 503 women participated. 42% (212/503) reported pain in the lumbopelvic region and 39% (196/503) fulfilled the criteria for a probable PGP diagnosis. 27% (137/503) reported both the posterior pelvic pain provocation (P4) and the active straight leg raise (ASLR) tests positive at baseline in week 18, revealing 7.55 (95% CI 5.54 to 10.29) times higher mean number of days with bothersome pelvic pain compared with women with both tests negative. They presented the highest scores for workload, depressed mood, pain level, body mass index, Oswestry Disability Index and the number of previous pregnancies. Exercising regularly before and during pregnancy was more common in women with negative tests.
CONCLUSION: If both active straight leg raise (ASLR) and posterior pelvic pain provocation (P4) tests were positive mid-pregnancy, a persistent bothersome pelvic pain of more than 5 days per week throughout the remainder of pregnancy could be predicted. Increased individual control over work situation and an active lifestyle, including regular exercise before and during pregnancy, may serve as a PGP prophylactic.
KEYWORDS: back pain; maternal medicine; musculoskeletal disorders
Strengths and limitations of this study
We used a prospective design with SMS-Track system
in data collection, providing instant data on
participants’ situation, with automatically recorded
responses in a database, which minimises further
data handling and risk of error.
We applied clinical diagnostic tests with high validity
and reliability, recommended in the international
guidelines for the diagnosis of pelvic musculoskeletal
affliction in pregnancy.
There were frequent problems in reaching the
participants through some of the phone providers,
which led to SMS-Track data missing at random, but
a generalised estimating equation analytic approach
compensates for missing data in these instances.
The retrospectively collected information on pelvic
pain in previous pregnancies and pelvic pain before
pregnancy may produce bias.
From the Full-Text Article:
Pelvic girdle pain (PGP) during pregnancy
affects approximately half of all pregnant
women, and for 25%–30% the condition
becomes severe. [1, 2] The aetiology of
PGP is still unknown, and the underlying
mechanisms have not been fully investigated. [1, 2] Researchers have explored the
physical, psychological and socioeconomic
implications of PGP during pregnancy. 
Pain-related restrictions on physical activity
have been described, both during pregnancy
and after childbirth, and the psychological
impact on perceived health, sexual life and
quality of life has been explored, as well as the
prevalence of sick leave due to PGP. [3–6]
PGP is classified into specific (caused by
trauma) or non-specific (multifactorial). 
Several clinical tests are needed to diagnose
the latter, including pain provocation and
functional ability tests. However, there is still
no ‘gold standard’ for diagnosing PGP. The
European guidelines present evidence-based
recommendations for the diagnosis and treatment of
PGP, but inconsistencies on the definition as well as treatment
still prevail. [3, 7]
Classification of PGP can, according to guidelines,
only be reached after lumbar causes have been excluded
through a clinical examination.  All tests recommended
in the European guidelines have a very high specificity, but
generally a low sensitivity. Hence, it is recommended to
perform all the tests, as one negative test is not sufficient to
rule out PGP.  The posterior pelvic pain provocation test
(P4), for diagnosing sacroiliac joint dysfunction, and the
active straight leg raise test (ASLR), for detecting failing
force closure, have shown high validity and reliability. [8–10]
In a Swedish study, substantial agreement between examiners
using ASLR and P4 tests was found in discriminating
non-specific lumbopelvic pain into lumbar pain and PGP
in pregnant women.  Together with a description of pain
location, these tests are considered relevant when evaluating
affliction in pregnant women likely to have PGP. 
So far, the longitudinal course of PGP in pregnancy
is incompletely examined. In prospective studies data
are usually collected at baseline and at one or a few
follow-ups. Measuring only at a few points in time may
indicate stability in the examined condition, and a fluctuating
course may be missed. A difference could reflect
only a temporary fluctuation in an otherwise stable
condition. Accordingly, a more frequent data collection
is warranted to accurately describe the clinical course.
Mobile phones and text messages have previously been
found feasible when collecting frequent longitudinal data
in clinical settings. [13–15] Phones are usually at hand in daily
life; hence, this method yields a high response rate for
The objective of this study was to explore if pregnant
women with probable PGP, subgrouped following
the results from two valid and reliable clinical tests recommended
in the European guidelines, differ in demographic
and clinical characteristics at mid-pregnancy and
in weekly amount of days with bothersome symptoms
through the second half of pregnancy. The hypothesis
was that sacroiliac dysfunction and failing force closure
diagnosed at mid-pregnancy may predict a course of bothersome
symptoms through the second half of pregnancy.
This is a prospective longitudinal cohort study of pregnant
women who had their second-trimester routine
ultrasound examination in pregnancy week 18 at an
obstetric outpatient clinic at Stavanger University
Hospital, Norway, from mid-March to mid-June 2010.
At the hospital, all the women were asked by a midwife
about their experience of pain in the lumbopelvic region.
The inclusion criteria were current lumbopelvic pain or
isolated pelvic pain, singleton pregnancy and good proficiency
in the Norwegian language. Women who met the
criteria were informed about the study, handed a letter
of consent to fill in if they agreed to participate, and an
envelope with questionnaires on demographic and clinical
data to complete at home. An appointment with a
chiropractor for a physical examination was arranged,
and the women were asked to bring the completed questionnaires
with them to the consultation. Women without
pain symptoms were informed about the study, handed
a letter of consent to fill in if they agreed to participate,
and a questionnaire on demographic data to complete
and leave at the reception on departure. All consenting
women were followed from week 18 with weekly, automated
text messages (SMS-Track).
Two chiropractors (SM and IK) performed a physical
examination of the pelvic region, including diagnostic
tests recommended in the European guidelines for the
diagnosis and treatment of PGP, and a neurological examination
of the lower extremities. 
Sequence of stability and pain provocation tests for PGP
Active straight leg raise
The test is performed with the patient in a supine position
with a straight leg and the feet 20 cm apart. The test
is performed after the instruction ‘try to raise your legs,
one after the other, above the couch for 20 cm without
bending the knee’.
The patient is asked to score impairment on a 6–point scale:
not difficult at all = 0;
minimally difficult = 1;
somewhat difficult; difficult = 2;
fairly difficult = 3;
very difficult = 4;
unable to do = 5.
The scores on
both sides are added, so that the total score range from
0 to 10.9
The patient, lying supine, flexes the knee and hip of the
same side, the thigh being crowded against the abdomen
with the aid of both the patient’s hands clasped about
the flexed knee. The patient is then brought well to the
side of the table, and the opposite thigh is slowly hyperextended
by the examiner with gradually increasing force
by pressure of the examiner’s hand on top of the knee.
With the opposite hand, the examiner assists the patient
in fixing the lumbar spine and pelvis by applying pressure
over the patient’s clasped hands. The test is positive if the
patient experiences pain, either local or referred on the
provoked side. 
Long dorsal sacroiliac ligament test
The subject lies on her side with slight flexion in both
the hip and knee joints. If the palpation causes pain that
persists more than 5 s after removal of the examiner’s
hand, it is recorded as pain. If the pain disappears within
5 s, it is recorded as tenderness. 
Modified Trendelenburg’s test
The patient stands on one leg, and flexes the other at
90° in the hip and knee. If pain is experienced in the
symphysis, the test is positive. 
Patrick’s FABER test
The subject lies supine. One leg is flexed, abducted
and externally rotated (FABER, abbreviation of flexion
abduction and external rotation) so that the heel rests on
the opposite knee. If pain is felt in the sacroiliac joints or
in the symphysis, the test is considered positive. 
Posterior pelvic pain provocation test
The test is performed with the woman supine and the
hip flexed to an angle of 90° on the side to be examined:
a light manual pressure is applied to the patient’s
flexed knee along the longitudinal axis of the femur
while the pelvis is stabilised by the examiner’s other hand
resting on the patient’s contralateral superior anterior
iliac spine. The test is positive when the patient feels a
familiar well-localised pain deep in the gluteal area on
the provoked side. A similar test is described as posterior
shear or ‘thigh trust’. [17, 18]
Symphysis palpation test
The subject lies supine. The entire front side of the pubic
symphysis is palpated gently. If the palpation causes pain
that persists more than 5 s after removal of the examiner’s
hand, it is recorded as pain. If the pain disappears within
5 s, it is recorded as tenderness. 
A demographic questionnaire used in an earlier study
on pelvic pain in pregnancy was filled in at baseline. 
The women marked the pain location on drawings with
the pelvis and the low back demarcated. Pain intensity
was rated on a Numerical Rating Scale (NRS) from 0
to 100, where 0 meant ‘No pain’ and 100 ‘Unbearable
pain’. Information on pain-related activities of daily living
(ADL) was collected through the Oswestry Disability
Index (ODI), which at the time of the data collection
was one of the principal outcome measures for defining
disabling effects from spinal disorders and PGP. [7, 20] It is
a patient-completed questionnaire which gives a subjective
percentage score of the level of function (disability)
in 10 ADLs in patients with low back pain. Every activity
contains six statements on how it is performed. The
statements are scored from 0 to 5, with the first statement
scoring 0 through to the last at 5. The scores for all
questions answered are summed, then multiplied by 2 to
obtain the index (range 0–100). Zero is equated with no
disability and 100 is the maximum disability possible.
Physical workload was measured through five answer
categories ranging from ‘sedentary’ to ‘ heavy’, following
a scale used in Stockholm Public Health questionnaire. 
The question on job satisfaction was a bipolar 5–point
Likert scale with increments in two opposite directions
(‘Very bad’ and ‘Very good’) and a neutral point in the
Every Sunday the women were asked through a short
message service (SMS) how many days the previous week
they had experienced bothersome pelvic pain: ‘How
many days during the previous week has your pelvic pain
been bothersome, (ie, affected your daily activities or
routines)?’ If there was no reply, the question was repeated
24 hours later. The question should be answered with one
single number between 0 and 7. The response was automatically
entered into a database, which collected the
continuous information from each participant over the
duration of the study.
Demographic descriptive data are presented as median
values with IQRs for continuous variables, and as frequencies
for categorical variables. For univariate comparisons
between symptomatic and asymptomatic subgroups,
the non-parametric Kruskal-Wallis statistics were used.
Categorical predictors in our model were four groups
following the outcome from the ASLR and P4 tests (1: P4
positive, 2: ASLR positive, 3: both P4 and ASLR positive, 4:
ASLR and P4 negative), time (pregnancy week), and the
interaction term between time and test group for investigating
whether the trajectory of SMS-reported number of
bothersome days differed between the test groups. Other
predictors in the model were age, number of previous
deliveries and body mass index (BMI) before pregnancy.
The longitudinal trajectory of the SMS-Track response
was modelled using a generalised estimating equations
(GEE) approach, extending the generalised linear model
to correlated longitudinal data and clustered data within
subjects. The within-subject dependencies resulting from
repeated measurement were modelled assuming an
autoregressive relationship in the working correlation
matrix. As the outcome variable was count data (weekly
number of bothersome days with pain), the Poisson distribution
was assumed with a log-link function.
Data were analysed using SPSS V.22.0 software. The
Strengthening the Reporting of Observational Studies in
Epidemiology reporting guideline was used during the
writing of this article.
Patient and public involvement
Patients and the public were not involved in developing
the research questions, outcome measures, as well as in
the design and conduct of the study, or in the recruitment
(P4) tests positive,
compared with the estimate for women with both tests
negative. Women with both tests positive were estimated
with twice the amount of bothersome days per week
(table 3). For women with either P4 or ASLR test positive
and a lower incidence rate, the mean amount of bothersome
days was lower, but still estimated as approximately
1.5 times higher than for women with both tests negative.
For every pregnancy, the mean number of bothersome
days increased by 13.5%. Even a slightly higher BMI had
a significant impact on the mean amount of bothersome
days. Age had no impact.
Overall, 506 women agreed to participate in this study.
Three were excluded due to incomplete data. On ultrasound
examination in pregnancy week 18 did 42%
(212/503) of the women report pain in the lumbopelvic
region. A clinical examination revealed that 39%
(196/503) of the women fulfilled the criteria for a probable
PGP diagnosis, and 27% (137/503) showed positive
response to ASLR and P4 tests. A further 12 women
reported pelvic pain but did not respond to recommended
clinical tests, and were therefore placed in the
‘ASLR and P4 tests negative group’.
There were significant differences in some demographic
and clinical features at baseline between the women with
and without pelvic pain and with different test outcomes
Women with positive P4 and ASLR tests experienced
heavier workload. They also presented higher BMI at week
18, exercised less both before and during pregnancy, and
slightly more than one-third reported feeling depressed
during the pregnancy. Physical disability (ODI) and
pain level (NRS) at week 18 were considerably higher in
women with positive tests than in women reporting pain
but having negative P4 and ASLR tests (table 2).
Women with a positive ASLR, but negative P4 test, had
the highest number of previous pregnancies. Almost half
of the women with both P4 and ASLR tests positive had
been on sick leave during their pregnancy. Apart from the
P4 and ASLR, the long dorsal ligament test showed the
highest positive response rate, followed by the symphysis
provocation test (table 2).
The SMS-Track response rate was 75% (2,148 responses
to 2,877 sent messages). Due to a declining SMS-Track
response at the end of the pregnancy, we stopped our
SMS-Track analysis at week 38. A GEE analysis revealed
that all entered variables, except ‘age’, were significant
predictors for the number of days with bothersome pelvic
pain, and there was a significant interaction between
diagnostic group and time, implying that the time course
of days with bothersome pelvic pain was different for the
different test groups.
The estimated weekly mean number of days with
bothersome pelvic pain for the different test groups is
presented in figure 1. Women with both P4 and ASLR
tests positive experienced from week 18 a high weekly
mean number of days (H5) with bothersome pelvic pain
throughout the pregnancy. Women with both tests negative
showed a steadily rising number of bothersome days
throughout the pregnancy, from 0.5 day in week 18, to
2 days in week 37. The group with a P4 positive and an
ASLR negative test had approximately 3 days of bothersome
pelvic pain in week 18, which was considerably
lower than the group with both tests positive, but showed
rapidly increasing number of days with pain. In week 29,
the number of days with bothersome pelvic pain equalled
that of the group with both tests positive, and thereafter
matched this group. Women with a positive ASLR and a
negative P4 test also showed 3 days of bothersome pelvic
pain in week 18, but never reached the mean number of
bothersome days reported by women with P4 and both
The parameter estimates output showed the estimated
rate for experiencing bothersome days to be 7.5 times
higher in women with both active straight leg raise (ASLR) and posterior pelvic pain provocation
To our knowledge, this is the only study in which women
with pelvic pain in pregnancy have been followed with
SMS-Track. The main result of this study was that if
both P4 and ASLR tests were positive in pregnancy
week 18, a persistent pelvic pain of more than 5 days/
week throughout the remainder of pregnancy could be
predicted. If either test was positive in week 18, a similar
course was shown, but women with a positive P4 test
revealed a more uncomfortable course than women with
a positive ASLR test, who never reached the bothersome
levels of the other groups. Robinson and coworkers23
reported a similar outcome for the P4 test in a prospective
cohort study on the association between sociodemographics,
psychological and clinical factors measured at
mid-pregnancy, and disability and pain intensity at week
30. However, their data showed no significant association
between the ASLR test result and the disability and pain
intensity in pregnancy week 30.
Although women who had a positive ASLR test and
negative P4 test at baseline presented a comparatively low
mean number of bothersome days with pain, they also
had the highest mean number of previous pregnancies
and the highest mean rate of pelvic pain in previous pregnancies.
Interestingly, our data also revealed that they
exercised more frequently in comparison with women in
the other positive test groups, both before and during the
Since sufficient force closure of the sacroiliac joints requires
appropriate muscular, ligamentous and fascial interaction,
may women with pelvic pain in previous pregnancies
have experienced that exercising improves muscle activation,
recovers function and decreases pain. [24–26] Additionally,
experiences of pain prevention and rehabilitation in
previous pregnancies may work as an incitement to engage
in physical activity and regular exercise, both before and
Our analysis also revealed a significant difference
between the test groups in women described feeling
depressed, and that a prepregnancy BMI slightly higher
than average had a significant impact on the mean
number of bothersome days. Distress has previously
been identified as a factor associated with a higher
likelihood of PGP in pregnancy, as have a higher BMI
and a higher gestational age.  One previous study
found distress contributing to disability, but not to pain
Nevertheless, some individuals seem to tolerate pain
better, have less catastrophising tendencies and show
more positive social response to pain, regardless of
exposure to stressful circumstances and/or internal
distress.  Finally, women with a possibility to control
their own work situation have better health during
pregnancy than women without such chances. As indicated
in this study and confirmed in previous studies,
most pregnant women benefit from exercise since it
increases pain tolerance, improves or maintains physical
fitness, helps with weight management, reduces
the risk of gestational diabetes in obese women, and
enhances psychological well-being. [29–32]
A limitation of this study is the retrospectively collected
information on pain in previous pregnancies and pain
before pregnancy, which may produce biased results.
Another limitation was found in the data collection via
the SMS-Track system. In Norway, at the time of the study,
there were more mobile phone service providers than
in neighbouring countries, where SMS-Track studies
previously had been successfully performed. Unfortunately,
we had frequent problems reaching women
through some of the providers. These problems led to
data missing at random, but the GEE analytic approach
may in these instances compensate for missing data.
However, using the SMS-Track system in data collection
is also a strength in our study, since it provides instant
data on participants’ situation, and responses are immediately
recorded in a datasheet, which minimises further
data handling and risk of error.
If both active straight leg raise (ASLR) and P4 tests are positive at a clinical
examination in mid-pregnancy, a course of persistent
bothersome pelvic pain for more than 5 days per week
throughout pregnancy may be predicted. The number of
days per week with bothersome pelvic pain increases for
every added pregnancy, but individual control over work
situation and regular exercise may work as a PGP prophylactic
since it invigorates a positive impact on optimal
force closure of the pelvis, reduces risk of instability in
the pelvic joints and enhances overall well-being.
Since there is still no gold standard for diagnosing
pelvic girdle pain (PGP), particularly regarding the number of tests at the
clinical examination, we recommend further research in
this area, aiming at predictive, preventive and diagnostic
measures for identifying women at risk of developing PGP
in pregnancy. It would, for example, be interesting to see
if women with a history of PGP have a higher pain-related
anxiety and if it influences pain.
The authors gratefully acknowledge the midwives at
Stavanger University Hospital for assistance in collecting the data.
SM, IK, JPL, KA and IØ made substantial contributions to the
conception and design of the work and revising it critically for important intellectual
content. SM and IK performed the data collection. SM, IK and AMG controlled the
data. SM and KSB analysed the data. SM, JPL, KA, AMG, KSB and IØ made final
approval of the version to be published. SM agrees to be accountable for all aspects
of the work in ensuring that questions related to the accuracy or integrity of any
part of the work are appropriately investigated and resolved.
The Norwegian Chiropractic Association ( kiropraktikk. no; Storgata, Oslo,
Norway) funded the acquisition of an SMS-Track licence.
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