ARTICLE IN PRESS
Midwifery (2009) 25, 286–294
A randomised controlled trial evaluating the effect of
immersion bath on labour pain
Flora Maria Barbosa da Silva, MsC, RN (Nurse Midwife)a,Ã, Sonia Maria Junqueira Vasconcellos de
Oliveira, PhD, RN (Assistant Professor)b, Moacyr Roberto Cuce Nobre, MD, PhD (Assistant Professor)c
Sapopemba Birth Center, Rua Borges Lagoa no. 512 apto. 93-A, Vila Clementino, Sao Paulo,
CEP 04038-000, Brazil
Department of Maternal-Child and Psychiatric Nursing, School of Nursing, University of Sao Paulo, Brazil,
Avenida Dr. Eneas de Carvalho Aguiar, 419 CEP 05403-000, Sao Paulo, Brazil
Clinical Epidemiology Unit, Heart Institute (InCor) University of Sao Paulo, Medical School,
Avenida Dr. Eneas de Carvalho Aguiar, 44 CEP 05403-904, Sao Paulo, Brazil
ÃCorresponding author. E-mail addresses: ﬂora010101@yahoo.com.br (F.M.B. da Silva), firstname.lastname@example.org (S.M.J.V. de Oliveira),
email@example.com (M.R.C. Nobre).
Received 10 August 2006; received in revised form 16 April 2007; accepted 24 April 2007
Objective: to evaluate the effect of an immersion bath on pain magnitude during the ﬁrst stage of labour.
Design: a randomised controlled trial comparing the pain scores of bathing and non-bathing nulliparous women during
birth was employed.
Setting: the study was conducted at the Normal Birth Center of Amparo Maternal, Sao Paulo, Brazil.
Participants: 108 birthing women, with 54 women randomly assigned to each group.
Interventions: when the birthing women presented at 6–7 cm of cervical dilation, they were placed in an immersion
bath for 60 mins.
Outcome measures: pain scores, using a behavioural pain scale and a numeric scale, were recorded at two evaluation
time points: at 6–7 cm of cervical dilation and 1 h after the ﬁrst pain score evaluation.
Findings: at the ﬁrst evaluation, on the behavioural scale, the means were 2.1 for both groups (p ¼ 0.914; 95%
conﬁdence intervals (CI) 1.9–2.3 for the control group and 2.0–2.2 for the experimental group). On the numeric scale,
the means were 8.7 and 8.5 for the control and experimental groups, respectively (p ¼ 0.235; 95% CI 8.2–9.2 for the
control group and 8.1–8.9 for the experimental group). At the second evaluation, the pain score means for both scales
were statistically higher in the control group than in the experimental group. On the behavioural scale, the scores were
2.4 vs. 1.9, respectively, for the control and experimental groups (po0.001; 95% CI 2.2–2.6 for the control group and
1.7–2.1 for the experimental group). On the numeric scale, the scores were 9.3 vs. 8.5, respectively, for the control and
experimental groups (po0.05; 95% CI 8.9–9.7 for the control group and 8.1–8.9 for the experimental group).
Conclusions: mean labour pain scores in the control group were signiﬁcantly higher than those in the experimental
group. The present ﬁndings suggest that use of an immersion bath is a suitable alternative form of pain relief for women
& 2007 Elsevier Ltd. All rights reserved.
Keywords Immersion bath; Hydrotherapy; Pain; Labour; Randomised controlled trial
0266-6138/$ - see front matter & 2007 Elsevier Ltd. All rights reserved.
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A randomised controlled trial evaluating the effect of immersion bath on labour pain 287
The use of immersion baths during labour has Participants
become increasingly common among birth centres
and hospitals worldwide. In Brazil, an approach The study was carried out from October 2002
which emphasises fewer interventions during through June 2003 at the Normal Birth Centre of
labour and birth complements a trend in prenatal Amparo Maternal, a birth centre with an average of
and labour care which began in the 1970s (Diniz, 1000 births each month, located in the city of Sao
2005). Newer birth centres have introduced bath Paulo, Brazil, which uses active labour manage-
tubs as an alternative form of pain relief for ment. The inclusion criteria were: full-term nulli-
labouring women. parous women with a live, cephalic presenting
The relaxing effects of an immersion bath have singleton fetus; absence of clinical or obstetrical
been attributed to the physiological responses complications; cervical dilation less than or equal
produced by hot water immersion. Water immer- to 6 cm at the time of admission; intact amniotic
sion during labour can reduce anxiety and catecho- membranes or membranes broken for not more
lamine release, increase endorphin release, relax than 6 h prior to admission; and two or more
muscles, and promote buoyancy in the water which uterine contractions every 10 mins (active labour).
in turn decreases pressure on limbs and joints and
allows freedom of movement (Cluett et al., 2007).
Moreover, water immersion decreases blood pres-
Sample size considerations
sure via vasodilatation and blood ﬂow redistribu-
The number of births assisted by nurse–midwives at
tion. This technique is considered safe; immersion
the Normal Birth Center between June 1st and
bath has not been associated with longer labours,
August 7th 2001 was used as a reference to
increases in surgical intervention, or poor neonatal
estimate the sample size. During this period, 789
outcomes. However, to the author’s knowledge, no
study to date has that systematically evaluated normal deliveries by nulliparous women took place
at the centre. Cochran’s formula (1963) for
negative outcomes following water immersion
comparing the proportion of ﬁnite populations
was employed to calculate the likely sample size
Several studies have attempted to establish the
(n ¼ 108 women), and represents a probabilistic
effects of immersion bath on the mother–baby
sample of the women who would use the maternity
bionomy (Schorn et al., 1993; Cammu et al., 1994;
service. The power to detect the differences
Eckert et al., 2001). However, it is difﬁcult to
between the two groups’ means after the immer-
compare ﬁndings across studies because most
studies do not indicate the stage of labour in which sion bath was calculated using Open Epi software
(2006), with statistical power of 96.1% for the
the intervention was used. Moreover, in some
numeric scale and 79.0% for the behavioural scale.
cases, both nulliparous and multiparous women
were included in the sample, and this distinction is
an important factor in pain evaluation during Randomisation
labour. The use of oxytocin should be reported as
well, because it inﬂuences pain sensation. The women were allocated to the control or
Previous studies have relied on various instru- experimental groups according to a computer-
ments to measure the effects of immersion bath generated randomisation list. Each list number
on labour pain, including visual analogue scales was covered by a tab, which hid the assigned group
(Cammu et al., 1994; Benﬁeld et al., 2001) and the of the next subject from the researcher. This tab
use of peridural analgesia (Schorn et al., 1993; was removed only after signed consent was
Eriksson et al., 1997; Eckert et al., 2001; Ohlsson obtained from each woman. The women were
et al., 2001). However, the use of pharmacological included in the study in a pre-sorted sequence, in
analgesia is an indirect measure of pain sensation which they had an equal chance of being assigned
and does not reﬂect the woman’s subjective to either group.
evaluation of the pain magnitude. Labour and The women were invited to participate in this
vaginal birth involves a great deal of pain, and study after admission to the birth centre. Sao Paulo
relatively few studies have evaluated the effects of city has approximately 12 million inhabitants; the
water immersion on labour pain. Therefore, the majority of the female population choose to give
present study evaluated the effect of an immersion birth in public health centres. The Normal Birth
bath on pain magnitude during the ﬁrst clinical Center admits birthing women from all districts of
stage of labour. Sao Paulo and its surroundings. As discussed below,
ARTICLE IN PRESS
288 F.M.B. da Silva et al.
the prenatal care of these women was the capacity) equipped with a Cardalls heater. Fetal
responsibility of the primary health-care units, heart rate was monitored intermittently during the
which makes it difﬁcult to recruit participants bath period using a Toitus sonar Doppler. The
antenatally. Prior to inclusion in the study, each immersion bath lasted 60 mins and was timed using
woman was given a detailed explanation of the a Sport Timers chronometer. An Incoterms ther-
purpose and the methods of the study. A signed mometer was used to measure the water tempera-
consent form was obtained from all voluntary ture, and body temperature was monitored using a
participants, who were assured their right to Citizens thermometer.
withdraw from the study at any time.
Pain magnitude was evaluated by the behavioural
The research project was approved by the Research pain scale and the numeric scale. The behavioural
and Ethics Committee of the School of Nursing of pain scale (Bonnel and Boureau, 1985) is a measure
the University of Sao Paulo.
˜ that continually evaluates the behaviour of birthing
women, and was applied by the researcher.
Scoring manifestations of pain
In the control group, the birthing women did not The following ﬁve-point behavioural scale was
use the bath during labour. These women received employed to track each subject’s experience of
routine care from the Normal Birth Center and pain: Intensity 0—Normal respiration, no gasping,
remained in a room with other women. The routine no agitation. Intensity 1—The frequency or ampli-
care consisted of ambulation, amniotomy and tude of respiratory rates is modiﬁed during con-
oxytocin use when cervical dilation remained tractions. All manifestations are considered
unchanged for 3 h. Cardiotocography is routine manifestations of pain, whether they are inten-
following admission to the birth centre. It is not tional (i.e., in relation to the psychological train-
used for continuous fetal monitoring when the ing) or purely reactional. Intensity 2—In addition to
birthing woman receives augmentation, because the aforementioned manifestations, signs of ten-
keeping the woman conﬁned to the bed can affect sion appear during contractions; these include
labour progression. Therefore, fetal heart monitor- grasping reactions, such as the grasping of the
ing was intermittent, and if any change in heart sheet, the bed or the hand of another person within
rate was noticed, a cardiotocography examination reach. These reactions cease between contrac-
was performed. In the experimental group, the tions. Intensity 3—The manifestations deﬁned in
immersion bath was used during the active phase of level 2 persist between contractions, indicating an
labour, when the birthing women had achieved absence of relaxation. Intensity 4—Signs of relaxa-
6–7 cm of cervical dilation, and when pain sensa- tion may arise during contractions and possibly
tion had become more intense. between them. These signs include abrupt uncon-
In a previous study by Eriksson and colleagues trolled movements such as startle reactions.
(1999), the use of immersion bath was compared in In addition to the behavioural scale described
two groups of women: one group received the bath at above, a numeric scale represented by a horizontal
a cervical dilation of less then 5 cm and the other at line with numerical marks from zero to 10 was used
greater than 5 cm. The early bath was associated by each woman to quantify her sensation of pain. The
with prolonged labour, greater incidence of augmen- numeric scale for pain was shown to each birthing
tation, and more frequent peridural analgesia re- woman, and it was explained that zero denoted no
quests. These ﬁndings are consistent with the present pain and 10 denoted the worst imaginable pain. The
author’s clinical experience, and represent the researcher asked each woman to point with her ﬁnger
rationale behind offering the immersion bath to to the value that represented the pain she was
women that have achieved a cervical dilation of at experiencing at that moment during her labour. The
least 6 cm. Each labouring woman adjusted the water researcher then conducted a verbal conﬁrmation of
temperature to her preference and this temperature the designated value and recorded the datum.
was measured. Bath temperature did not exceed
38 1C. No chemicals were added to the water. Data collection
Each woman entered the tub and remained in the
water up to the nipple line. The immersion bath The researcher remained at the Normal Birth
equipment consisted of an Astras bath tub (194 L Center during each participant’s entire labour,
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A randomised controlled trial evaluating the effect of immersion bath on labour pain 289
which lasted 12 h on average. The researcher the effect of the immersion bath on the labour of
worked on alternate days of the week. All of the these women. There was no migration of birthing
data collection was performed by one of the women between the groups and no subjects with-
authors (F.M.B.S., a woman). There was no differ- drew from the study during the follow-up period.
ence in the number or characteristics of birthing
women attended on alternate days.
The data were collected in the following se- Birthing women, newborn babies and labour
quence: interview and randomisation; ﬁrst evalua- characteristics
tion carried out at 6–7 cm dilation, including pain
evaluation according to the numeric and beha- All of the birthing women had full-term pregnan-
vioural scales; and cervical dilation veriﬁcation. cies, and the majority were white, primiparous and
Body temperature and labour room temperature had partners. On average, they had 8 complete
were veriﬁed, as well as the water bath tempera- years of education. The ages of the women ranged
ture in the experimental group. The second from 15 to 31 years. The majority of women were
evaluation was performed at the end of the aged 19 years or younger (51.0%), with 48% being
immersion bath period, 1 h after the initial pre- 20–30 years old.
bath assessment. Pain scores and cervical dilation Clinical data from the birth centre indicated
were re-assessed during the second evaluation. that, historically, approximately 25% of the women
All women, regardless of allocation, received treated were p19 years of age (Birth Center
one-on-one care from the researcher. The birth was clinical data service, 2001). The results of a
assisted by the nurse–midwives of the Normal Birth Brazilian study with nulliparous women reported a
Center, but the researcher was at the side of the mean age of 18.6 years (Costa and Riesco, 2006),
birthing women. whereas European and Australian studies have
reported higher mean ages, e.g. 26.9 years (Downe
et al., 2004), 31 years (Carfoot et al., 2004) and 27
years (Shorten et al., 2002).
The data in Tables 1 and 2 indicate that the two
The Statistical Package for Social Sciences version
groups did not differ in terms of any of the assessed
8.0 was used for analyses. First, a descriptive data
independent variables, including race, number of
analysis was performed in order to describe the
gestations, marital status, membrane rupture
women, their labours and newborn baby character-
status, amniotic liquid appearance, oxytocin use,
istics. In the qualitative variable analysis, w2,
perineal condition, maternal age in years, scholar-
Pearson’s and Fisher’s exact tests were used. For
ship in years, gestational age in weeks, time from
quantitative variables, Student’s t-tests and Man-
rupture of the amniotic membranes until child-
n–Whitney U-tests were performed. p-values less
birth, cervical dilation at the time of oxytocin
than 0.05 were considered statistically signiﬁcant.
administration, length of expulsive period in
To analyse the relationship between the numeric
minutes, room, bath or body temperature, new-
and behavioural pain scales, Goodman and Krus-
born baby weight, and Apgar scores at 1 and 5 mins
kal’s Gamma tests were used. This test measures
(for all comparisons, p40.05). The time from
the association between ordinal variables, and is
rupture of the amniotic membranes to childbirth
represented by g.
was calculated from the rupture up to the cephalic
birth. Although this time was slightly higher in the
Findings control group than in the experimental group, the
small difference was not statistically signiﬁcant
Four women in the bath group were excluded from (p ¼ 0.082). If rupture of the amniotic membranes
the study due to cardiotocographic symptoms occurred at the point of fetal childbirth, the time
(n ¼ 2) or thick meconial liquid (n ¼ 2). Two between membrane rupture and childbirth was
women in the non-bath group were administered recorded as 0 mins. No group differences emerged
antihypertensive drugs and therefore required regarding cervical dilation at the time of oxytocin
continuous blood pressure monitoring. All six of administration.
these women received caesarean sections before In both groups, artiﬁcial membrane rupture
their cervixes had dilated to 6 cm and before the was more common than spontaneous amniotic
ﬁrst pain score evaluation was recorded. None of rupture. The incidence of meconial amniotic ﬂuid
these six women were given the intervention was higher in the control group (six cases) than in
(water immersion bath). It was not possible to the experimental group (one case), although this
evaluate the pain scores (primary outcomes) and difference was not statistically signiﬁcant. The
ARTICLE IN PRESS
290 F.M.B. da Silva et al.
Table 1 Study subject characteristics.
Variables Group p-valueÃ
n % n %
White 30 55.6 30 55.6 40.999
Not white 24 44.4 24 44.4
Number of gestations
Primiparous 53 98.1 52 96.3 40.999
Second gestation 1 1.9 2 3.7
In a relationship 36 66.7 32 59.3 0.425
Not in a relationship 18 33.3 22 40.7
Rupture of amniotic membranes
Spontaneous membrane rupture 18 33.3 12 22.2 0.197
Amniotomy 36 66.7 42 77.8
Amniotic liquid aspect
Clear 48 88.9 53 98.1 0.072
Thin meconium 2 3.7 1 1.9
Moderate meconium 4 7.4 — —
Yes 23 42.6 19 35.2 0.430
No 31 57.4 35 64.8
Intact 11 20.4 13 24.1 0.708
First degree 11 20.4 7 13.0
Second degree 5 9.3 7 13.0
Episiotomy 27 50.0 27 50.0
Total 54 100 54 100
Ã w2 test and Fisher’s exact test for cell number less than ﬁve.
presence of meconial ﬂuid can be an indicator of with an average of 35 1C. Cammu et al. (1994) and
fetal distress and is associated with fetal death, Eckert et al. (2001) used immersion bath tempera-
neonatal death and neonatal morbidity. In the tures higher than 37 1C, whereas Eriksson et al.
present study, the presence of meconial ﬂuid was (1997) reported use of temperatures higher than
not associated with increased newborn baby dis- 38 1C; neither study was associated with poor
tress as assessed by Apgar scores (Table 2). maternal or neonatal outcomes. The highest bath
In both groups, the majority of women (57.4% of water temperature (38 1C) used in this study was
the control group and 64.8% of the experimental within the range than the authors consider safe for
group) did not require oxytocin during labour. a 60-min treatment period.
Among the women who were given oxytocin, ﬁve Geissbuehler et al. (2002), in a prospective study
were administered the medication during the with 10,775 births, observed that birthing women
expulsive period (three from the control group are able to thermoregulate; the birthing women
and two from the experimental group); they were controlled the water temperature and bath time,
not considered to have received oxytocin during so the core body and fetal temperatures remained
labour, because the study parameters only consid- within the physiological range. Therefore, it is
ered the interventions during active labour. probable that rigid guidelines regarding the dura-
The bath water temperature, adjusted by the tion of the bath (60 mins in this study) and water
birthing woman, was between 27.0 and 38.0 1C, temperature are unnecessary and can disrupt
ARTICLE IN PRESS
A randomised controlled trial evaluating the effect of immersion bath on labour pain 291
Table 2 Study subject and newborn characteristics.
Variable Group Mean SD Median Min Max p-value
Age (years) Control 21.1 4.1 20.5 15.0 32.0 0.078
Experimental 19.7 3.6 19.0 14.0 30.0
Scholarship (years) Control 8.3 2.9 9.0 1.0 11.0 0.259
Experimental 8.0 2.6 8.5 1.0 14.0
Gestational age (years) Control 39.5 1.1 40.0 37.0 41.0 0.560
Experimental 39.5 0.9 39.5 37.0 41.0
Forewater rupture duration (mins) Control 249.4 195.6 179.0 15.0 870.0 0.082
Experimental 197.8 172.2 146.0 0 860.0
Dilation when using oxytocin (cm) Control 6.9 1.7 7.0 4.0 10.0 0.504Ã
Experimental 6.6 2.1 7.0 4.0 10.0
Expulsive period length (mins) Control 31.8 19.1 27.0 5.0 106.0 0.194Ã
Experimental 37.5 25.9 31.5 3.0 118.0
Setting temperature (1C) Control 23.6 3.7 24.0 15.0 30.0 0.484
Experimental 24.5 3.4 24.0 18.0.0 36.0
Temperature of birthing women (1C) Control 36.5 0.5 36.5 35.1 37.2 0.741
Experimental 36.3 1.6 36.5 35.0 37.7
Water temperature (1C) Experimental 35.1 2.0 35.0 27.0 38.0 —
Newborn weight (g) Control 3316.8 367.4 3302.5 2760.0 4425.0 0.129Ã
Experimental 3205.5 389.0 3205.0 2585.0 4045.0
Apgar score at 1 minute Control 8.8 0.5 9.0 7.0 9.0 0.289
Experimental 8.7 0.5 9.0 7.0 9.0
Apgar score at 5 minutes Control 9.5 0.5 9.5 8.0 10.0 0.399
Experimental 9.4 0.5 9.0 9.0 10.0
Ã Student’s t-test for normal distribution, Mann–Whitney U-test for non-parametric comparisons.
normal thermoregulation. The Apgar scores indi- exhibited a lower overall score than the control
cated good newborn baby health, although the group (1.9 vs. 2.4). Oxytocin administration did not
present study was not designed to study neonatal inﬂuence the behavioural scale scores in either
outcomes. group (Table 4).
Interestingly, for the self-reported numeric scale
scores of the control group, there was an increase
Pain scores over the two evaluations, whereas in the experi-
mental group, the pain scores remained relatively
An initial evaluation of the pain scores was constant over the two evaluations (Table 3). The
performed as soon as each woman arrived at the experimental group reported lower numeric scale
labour ward and after her randomisation and pain scores than the control group (8.5 vs. 9.3),
informed consent were conducted. In this ﬁrst with a statistically signiﬁcant difference for the
evaluation, the mean behavioural scale results were second evaluation. Similar to the results with the
1.6 for the control group and 1.7 for the experi- behavioural scale, oxytocin use did not affect the
mental group (p ¼ 0.591), and the numeric scale numeric scale scores for either group (Table 4).
scores were 7.1 and 6.7 (p ¼ 0.405) in the control It was noted that the maximum level of pain in
and experimental groups, respectively. A trend the behavioural scale was only recorded in the
towards higher pain levels is expected as labour control group (one subject). By contrast, the
progresses and the contractions intensify. For the maximum level was recorded on the subjective
second evaluation, there was a statistically signiﬁ- numeric scale by women in both groups (38
cant difference between the groups (po0.001). subjects in the control group and 19 subjects in
On the behavioural scale, the experimental group the experimental group). Goodman and Kruskal’s
ARTICLE IN PRESS
292 F.M.B. da Silva et al.
Gamma test yielded an association index of scores than the control group (49 vs. 64, on a visual
g ¼ 0.85 (positive association) for the control group analogue scale), veriﬁed 30 mins after the begin-
and g ¼ 0.95 (positive association) for the experi- ning of the intervention (Cluett et al., 2004).
mental group, verifying that there was indeed a In the present study, the pain sensations of
valid association between the numeric and beha- labour, which intensify as labour progresses, ap-
vioural scales. This demonstrates that, in both peared to increase more gradually in women
groups, the intensities of pain recorded by the exposed to the water immersion bath. This ﬁnding
birthing women and by the researcher were is similar to the results of Cammu et al. (1994), who
consistent. evaluated, with a visual analogue scale, the pain
sensations of birthing women who did or did not use
an immersion bath during labour. Although these
Discussion researchers observed similar pain scores for
women regardless of immersion bath use, a signi-
This study evaluated both observer-scored (beha- ﬁcantly more gradual increase in the pain sensa-
vioural scale) and self-reported (numeric scale) tions in the immersion bath group was observed
pain scores for women given a water immersion (Cammu et al., 1994).
bath or no bath during active labour. Both pain Mackey (2001) reported that several studies have
scores differed (po0.001 and po0.05) at the found that women who used the immersion bath
second assessment (Table 3). These results are required less frequent use of analgesia and anaes-
consistent with those obtained in a randomised thesia during childbirth, and these ﬁndings were
clinical study, which evaluated the inﬂuence of conﬁrmed by Cluett et al. (2007). These authors
immersion bath on nulliparous women with dystocia concluded that the use of an immersion bath
or cervical dilation of less than 1 cm/h. The during labour reduces reported maternal pain.
experimental group exhibited signiﬁcantly lower However, the use of analgesia, anaesthesia or pain
Table 3 Behavioural scale and numerical scale scores for the ﬁrst and second evaluations.
Scale Evaluation Group Mean SD Median CI 95%a p-valueb
Behavioural scale First Control 2.1 0.6 2.0 1.9–2.3 0.914
Experimental 2.1 0.5 2.0 2.0–2.2
Second Control 2.4 0.7 2.5 2.2–2.6 o0.001
Experimental 1.9 0.7 2.0 1.7–2.1
Numeric scale First Control 8.7 1.7 9.0 8.2–9.2 0.235
Experimental 8.5 1.4 9.0 8.1–8.9
Second Control 9.3 1.4 10.0 8.9–9.7 o0.05
Experimental 8.5 1.6 9.0 8.1–8.9
Table 4 Behavioural scale and numeric scale scores relative to oxytocin use.
Scale Group Oxytocin use n Mean SD Median Min Max p-value
Behavioural scale Control Yes 7 2.6 0.8 3.0 1 3.0 0.415
No 47 2.4 0.8 2.0 1 4.0
Experimental Yes 10 1.7 0.8 2.0 0 3.0 0.46
No 44 1.9 0.6 2.0 1 3.0
Numeric scale Control Yes 7 9.6 1.1 10 7 10 0.424
No 47 9.3 1.4 10 4 10
Experimental Yes 10 8.4 1.7 9 6 10 0.927
No 44 8.5 1.5 9 4 10
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A randomised controlled trial evaluating the effect of immersion bath on labour pain 293
medication is not a reliable measure of the and reported by the women were consistent.
effectiveness of the bath in the relief of labour However, it is difﬁcult for a healthy, nulliparous
pain, because it does not measure the pain directly woman to imagine what she would consider ‘the
(Simkim and O’Hara, 2002). worst imaginable pain’, given that this estimate is
There are some limitations to the present study. linked to previous experiences of pain.
It is important to consider the reasons for inviting It would be interesting to report the puerperal
women to participate in the study although they infection rates among the women in this study.
were in active labour. As publicly insured women do However, such a measure was not possible because
not have a choice where they will give birth, it is the research locale does not offer a follow-up
not possible to obtain informed consent prior to service for postpartum women. The study was not
their admittance to the birth centre. Once these designed to evaluate the effects of the immersion
women arrived at the centre, the researcher bath on neonatal outcomes, although it was noted
explained the purpose of the study and that she that it had no adverse effects on the immediate
would remain with the woman for the remainder of health (Apgar) scores of the babies.
her labour. This practice is not part of routine care Due to the nature of water immersion, it was not
in maternity services in Brazil, and may have possible to blind the birthing women or caregivers
contributed to the consent of the women who to the intervention. In fact, the gold standard
participated in the study. design for assessing an intervention is believed to
Pain intensity can be evaluated either by be the double-blind randomised trial. However, in
subjective reports of pain experience, or by general, blinding is impossible when the interven-
evaluation by an observer. However, as pain is a tion is a highly visible component of care (Downe
complex phenomenon, it should be assessed by two et al., 2004). As Cluett et al. (2007) suggests, not
or more methods, or in a qualitative study. In the all participants or caregivers will have the same
present study, the association analysis revealed opinion about the immersion bath, which can in
that pain measurements taken by the researcher turn positively or negatively inﬂuence outcomes
Assessed for eligibility in the first
stage of labour (n = 114)
Bath group Non-bath group
Assigned to intervention group in the first Assigned to control group in the second stage
stage of labour (n = 58) of labour (n = 56)
Received allocated intervention (n = 54) Received allocated intervention (n = 54)
Did not receive allocated intervention (n = 4) Did not receive allocated intervention (n = 2)
Reasons: four women had caesarean section Reasons: two women had hypertension and
before the intervention they had caesarean section before the
Analysed (n = 54) Analysis Analysed (n = 54)
Excluded from analysis (n = 0) Excluded from analysis (n = 0)
Figure 1 Flow diagram of trial participants: initial and ﬁnal inclusion.
ARTICLE IN PRESS
294 F.M.B. da Silva et al.
such as pain perception, analgesia use and mater- Carfoot, S., Williamson, P.R., Dickson, R., 2004. The value of a
nal satisfaction. A ﬁnal limitation of this study is pilot study in breast feeding research. Midwifery 20,
the fact that the women given an immersion bath 188–193.
Cluett, E.R., Nikodem, V.C., McCandlish, R.E., Burns, E.E., 2007.
were removed from the routine labour setting, Immersion in water in pregnancy, labour and birth (Cochrane
where they would have been with other labouring Review). In: The Cochrane Library, Issue 1, 2007. Update
women. This may have had a relaxing inﬂuence, by Software, Oxford.
providing privacy and tranquility. Cluett, E.R., Pickering, R.M., Getliffe, K., James, N.S.G.S.,
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