Mondcz-Bauer
et
al.,
Effects
of
Standing
position
on
spontaneous
uterinc
contractility
89
Original contributions
J.
Perinat. Med.
3
(1975)
89
Effects
of
standing
position
on
spontaneous
uterine
contractility
and
other
aspects
of
labor
C.
Mendez-Bauer*,
J.
Arroyo,
C.
Garcia Ramos,
A.
Menendez,
M.
Lavilla,
F.
Izquierdo,
I.
Villa
Elizaga**,
J.
Zamarriego***
Depts.
of
Obstetrics
and
Neonatology
of the
Maternidad
"Santa
Cristina",
Madrid,
Spain
Ministry
of
Education
and
Sciences,
Scientific
Research Council
Received
July
23,
1974. Accepted October
15,
1974.
It
has
been
shown
that changing
the
maternal
position
during
labor
may
have
an
influence
on
uterine contractility.
WILLIAMS
1952
[9]
reported
on one
patient,
whose
contractions
became
more intense
when
she
was in
sitting
position,
using
internal
toco-
graphy.
Two
years
later,
VON
LORAND
and
POGANY
[8], using external tocography,
claimed
that
the
recumbent
position
increased uterine
contractions. These observations
were
made
during spontaneous labor,
in
nulliparae
with
intact
membranes.
BOSCH,
IKLE
and
KÄSER
1954
[4]
and
CALDEYRO
et al.
1960
[6]
demonstrated, that
uterine contractions were stronger
and
less
frequent
when
the
patient
lay
on her
side
(left
or
right), than when
she was
supine.
When
evaluating
the
effects
of
maternal position
on
uterine
contractility,
it
should
be
recalled
that several other,
factors
including
parity, con-
dition
of the
membranes
and
medication
given
to the
mother,
may
also
influence
spontaneous
uterine contractility
and
labor.
The first
objective
of
this
paper
is to
study
the
effect
of
standing
position
on
spontaneous
uterine contractility,
when
these
factors
are
taken
into
account.
Furthermore
the
influence
of
the
maternal position
on the
pain
produced
by
contractions,
comfort
of the
patient
and
duration
of
labor have
not
been studied,
in our
knowledge.
An
additional
aim is to
study
the
effects
of
standing
position
on the
duration
of
labor, pain
produced
by
uterine contractions
and
comfort
Curriculum vitae
CARLOS
MENDEZ-BAUER
was
born
in
Montevideo
(Uruguay)
in
1930.
He
completed
bis
studies
there
and
gradtiated
äs
Doctor
in
Mediane
at the
Faculty
of
Medicine,
Uni-
versity
oftbe
Repttblic,
Monte-
video
(Uruguay).
In
1952
be
joined
the
Service
of
Obstetri-
cal
Physiology,
directed
by
R.
CALDEYRO-BARCIA.
Sinee
tbat
time
he has
become
inter-
ested
in
uterine
physiology,
endocrinology
of
labor,
and
physiology
of the
fetus
and
newborn.
In
1966
he
was
appointed
cbief
of the
Service
of
Obstetrical
Physiology>,
Montevideo
(Urttr
guay).
He
moved
in
1969
to
USA,
where
he
remaimd
for one
year
äs
Associate
Professor
of
Obstetrics
and
Gynecology
and
Physiology
at the
University
of
Minnesota.
Returning
to
Monte-
video
he
participated
in the
activities
of the
Latin
American
Center
of
Perinatology
and
Human
Development
(CLAP),
institution
sponsered
by P. A. H. O.
(WHO).
In
1973
he
joined
the
Maternidad Santa
Cristina,
Madrid,
Spain,
to
develop
a
program
of
care
and
research
in
Perinatology
in
cooperation
with
the
Department
s of
Obstetrics,
Gynecology
and
Neonatology.
He has
published
severaipapers
and
articles
in
connection
with
perinatal
Problems.
of
the
patient since,
to our
knowledge these
have
not
hitherto
been studied.
*
Chief,
Research
Department.
**
Chief,
Department
o£
Neonatology
&
Perinatal
Medicine.
***
Director
and
Chief,
Department
of
Obstetrics
and
Gynecology.
J.
Perinat. Med.
3
(1975
90
Mendez-Bauer
et
al.,
Effects
of
standing
position
on
spont neous
uterine
contractility
i
o4
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J.
Perinat.
Med.
3
(1975)
Mondcz-Bauer
et
al.,
Effccts
of
Standing
position
on
spontaneous
uterine
coptractility
91
l
Material
and
methods
Twenty normal spontaneous labors
with
vertex
presentation
were
studied. This group
was
selected
at
random
from
among
the
normal
pregnant
nulliparae
that came
to
deliver
at our
Hospital.
They were
told
that
their
position
would
be
changed
during
labor,
but
were
not
told
what
effect
this
change
in
position
might
have.
No
oxytocics, sedatives,
nor any
other
medication,
were given
to the
mother
during
labor.
Additional
clinical
Information
is
presented
in
Tab.
L
The
study began when spontaneous uterine
contractions
were present
and
cervical
dilatation
was
at
2—3
centimeters.
At
this
time
recording
o£
uterine
contractility
was
started,
by
placing
an
open
tip
catheter
into
the
Uterus,
either intra-
or
extra-amniotically,
according
to the
condition
of
the
membranes
(ruptured
or
intact).
The
degree
of
cervical dilatation
at the
time
of
mem-
brane
ruptured
is
shown
in
Tab.
L The
saline
filled
catheter
was
connected
to a
pressure
transducer
(8021A
Hewlett-Packard
Cardioto-
cograph).
The
System
was
frequently
flushed to
avoid recording
artifacts.
The
pressure transducer
was
attached
to the
maternal abdomen
close
to
the
fundus
of the
uterus
to
roughly compensate
for
the
changes
in the
"zero
level"
occurring
when
the
patient moved
from
supine
to
Standing
or
viceversa.
The
rationale
of
this
modification
to the
Standard
technique
of
attaching
the
mano-
meter
to the
monitor
is
discussed elsewhere
[2].
1.1
Method
of
procedure
The
patients were asked
to
change
from
supine
to
Standing
position
or
viceversa
at
intervals
of
30
minutes.
The first
position
was
selected
at
random. They were allowed
to
walk
or
rest
in a
chair
for
short intervals during
the
Standing
period,
if
they wished
so. A
vaginal examination
was
perf
ormed
—
always
by the
same
observer
—
at the
onset
of the
study
and at the end of
each
period
of 30
minutes.
The
characteristics
of the
cervix
were
carefully
evaluated.
The
study
was
continued
until
füll
cervical dilatation
was
attained.
The
second stage
was
managed with
local
anesthesia
to the
perineum
and the
patient
lying
in
supine
position.
General anesthesia
or
analgesia
was not
used, except
for
operative
deliveries.
As
much
äs
possible,
the
environ-
mental
conditions were kept constant throughout
labor.
At the end of the
study,
the
patients were
asked
to
assess
the
pain caused
by
uterine con-
tractions
in
each position,
and to
state which
position
was the
most comfortable
for
her.
Fetal heart rate
was
also monitored, either
by
ultrasound
or by ECG
using
a
scalp
electrode
and
the
above mentioned monitoring
equipment.
The
newborns were examined
by a
neonatologist,
and the
AP
GAR
score
was
perf
ormed
at the
Ist,
5th and
lOth
minute
of
life.
The
corresponding
scores
are
showed
in
Tab.
L
1.2
Quantitative
analysis
of the
tracings
of
uterine
contractility
[5, 6]
1.
Intensity
of the
contractions
was
measured
in mm Hg
from
the
baseline (tonus)
to the
peak
of
each uterine contraction.
Only
contractions
having
an
intensity over
5 mm Hg
were con-
sidered.
2.
Frequency
of the
contractions
was
measured
by the
reciprocal
of the
time elapsed
from
the
peak
of the
contraction
to the
peak
of the
pre-
ceding
one.
The
result
was
expressed
äs
the
number
of
contractions
per 10
minutes.
To
calculate
the
frequency,
only
contractions having
more
than
5 mm Hg of
intensity were considered.
3.
Uterine
activity
was
calculated multiplying
the
intensity times
the
frequency
of the
contrac-
tions.
The
result
was
expressed
äs
mm Hg per
10
minutes,
or
Montevideo Units.
4.
Uterine
tonus
was not
analyzed
in the
present study
since
the
changes
in
maternal
position
made
the
measurement
inaccurate.
1.3
Statistical
analysis
of the
tracings
of
uterine
contractility
1.
Intensity
of
contractions.
For
every
patient,
the
values
of
intensity
of all the
contractions
recorded
in
each maternal
position,
were averaged.
The
corresponding
two
mean values (patient
in
supine
or
Standing position) were compared
by a
Student's
test
(2
). The
significance
of the
difference
between
the
means
found
in
each case
are
shown
in
Fig.
3. A
value
of p <
0.05
was
J.
Perinat.
Mcd.
3
(1975)
92
Mendez-Bauer
et
al.,
EfFects
of
Standing
position
on
spontaneous uterine contractility
considered
äs
significant.
Those
cases
showing
a
significant
increase
in
the
intensity
of
the
con-
tractions,
when
changing
the
patient
from
supine
to
standing
position,
were
considered
äs
"po-
sitive".
When
the
intensity
of
contractions
did
not
change
or
decreased
significantly
(only
patient
17) the
observation
was
considered
äs
"negative".
Each patient
was
thus
classified
äs
positive
or
negative.
The
series
was
continued
until
the
ratio
of
positive
and
negative obser-
vations
reached
a
significant
level
(p <
0.05)
by
a
sequential analysis.
This
criteria
was
employed
to
determine
the
size
of the
sample
(20
patients
in
total).
2.
Frequency
of
uterine contractions
—
uterine
activity.
The
method
of
statistical analysis
used
for
these parameters
was
similar
to
that
of
intensity.
But no
sequential test
was
applied
since
their changes were
not
consistent
in the
succesive observations.
2
Results
2.1
Uterine
contractility
The
effects
of
changing'
'maternal
position
on
uterine
contractility
will
be
discussed
separately
for
each
one of the
parameters
studied.
2.1.1
Intensity
The
intensity
of
contractions
increased
sig-
nificantly
(p <
0.05)
in the
standing
position
in
fifteen out of the
twenty
patients
studied.
It
did
not
change significantly
in
four
patients
and
decreased significantly
in one (
17)
(Fig.
3).
These results were
evaluated
patient
by
patient
by
sequential analysis.
The
proportion
of
positive
versus
negative
observations,
found
for the
group
of
twenty
patients,
was
significant
to a
level
of p <
0.05.
Figures
l, 2 and 6 are
typical
examples
of the
effects
of
changing
position
on
uterine
contractility.
In
general,
the
intensity
of
PDPR3
143
l
5?
00.30 00.40
00.50
Fig.
1.
Original tracing
obtained
in a
normal pregnant
19years
old
patient.
Vertex
Präsentation.
Gesta
I,
Para
0,
39th
week
of
amenorrhea.
Membranes
were
spontaneously
ruptured
at the
onset
of the
study
(hour
00:00).
At
hour
00:40,
the
cervical
dilatation
was 5 cm and
presentation
at
Station
— 1.
Spontaneous
delivery occurred
at
hour
02:15.
Female newborn; weight
2.950g.
APGAR
score
7, 8 and 9 at the
Ist,
5th
and
lOth
minute
of
life.
Note that
the
intensity
of
contractions
was
higher
and the
frequency
was
lower
in
stand-
ing
position.
Also,
contractions
appeared
better coordinated
in
this position.
All
changes developed rapidly.
At
hour
00:42,
fetal
pH was
7.37
and
maternal
pH was
7.48.
It
took
2
hours
and 15
minutes
to
dilate
from
3 to 10
centimeters (Tab.
I).
(Same
patient
äs
in
Fig.
2.)
.
J.
Peririat.
Med.
3
(1975)
Mondez-Bauer
et
al.,
Effccts
of
Standing position
on
spontancous
uterinc
coptractility
93
01:10
HOUR
01,20
01>30
01
35
Fig.
2.
Same
patient
äs
in
Fig.
1.
At
hour
01:20,
the
cervix
attained
9 cm
dilatation
and the
presentation
was in
Station
0.
When
the
mother
changed
from
supine
to
Standing position,
uterine
contractions became
more
intense,
less
frequent
and
better coordinated.
The
patient reported
equal
pain
with
contractions
in
both positions, although they
were
re-
markably
more intense
in
Standing
than
in
supine position. Fetal
pH at
hour
01:15
was
7.37.
Note
the
frequent
flushings of
amniotic pressure recording, performed
in
supine position,
to
corroborate
the
reliability
of
the
tracing. Bearing down
efforts
appeared
at
hour
01:33.
Delivery occurred
at
hour
02:15
(see legend
of
Fig.
1).
contractions
diminished
when
the
patient moved
from
standing
to
supine
position
(Fig.
1). The
opposite
effect
was
seen when
the
patients moved
from
supine
to
standing
position
(Fig.
2, 6). The
changes
in the
intensity
of
contractions were
very
rapid,
involving
one or two
contractions
to
develop
and
they lasted
until
maternal position
was
changed again.
2.1.2
Frequency
Significant
changes
were
found
in
only
seven
patients.
In six of
them,
the
frequency
of
con-
tractions diminished when
the
patient changed
from
supine
to
standing position
and it
increased
in the
remaining
one (
17).
The
twelve other
patients
had no
significant
modifications
in the
frequency
of the
contractions,
in
relation
to
their
position (Fig.
4).
Figures
l and 2
illustrate
one
of
the six
patients whose
frequency
of
contractions
diminished
significantly
in
standing position.
The
changes
in the
frequency
also developed
äs
rapidly
äs
those
of the
intensity.
2.1.3 Uterine activity
This
increased
significantly
in
half
of the
patients
studied
(Fig.
5)
äs
a
consequence
of the
combined
effect
of the
changes
in
intensity
and
frequency
of
contractions
in
each case.
2.1.4 Coordination
Although
it is
difficult
to
evaluate
this
parameter
objectively,
an
analysis
of the
tracings
indicated
that irregularities
in the
shape,
rhythm
and
intensity
of the
contractions were more fre-
quent
in
supine
than
in
standing
position
(Figs.
l, 2, 6).
?
Comparison between
the
patterns
of
uterine
contractility
recorded
in the two
different
po-
sitions studied suggested
that,
according
to
CALDEYRO,
ALVAREZ
and
REYNOLDS
[5], uterine
contractions were better coordinated
in the
standing than
in the
supine position.
Thus,
in the
standing position uterine contractions
showed
a
consistent increase
in
their intensity
compared
to the
activity
in the
supine position.
J.
Perinat.
Mcd.
3
(1975)