Baciuk (2008) Water aerobics in pregnancy- cardiovascular response, labor and neonatal outcomes

Background: To evaluate the association between water aerobics, maternal cardiovascular capacity during pregnancy, labor and neonatal outcomes.

Methods: A randomized, controlled clinical trial was carried out in which 34 pregnant women were allocated to a water aerobics group and 37 to a control group. All women were submitted to submaximal ergometric tests on a treadmill at 19, 25 and 35 weeks of pregnancy and were followed up until delivery. Oxygen consumption (VO2 max), cardiac output (CO), physical fitness, skin temperature, data on labor and delivery, and neonate outcomes were evaluated. Frequency distributions of the baseline variables of both groups were initially performed and then analysis of the outcomes was carried out. Categorical data were compared using the chi-square test, and numerical using Student’s t or Mann-Whitney tests. Wilk’s Lambda or Friedman’s analysis of repeat measurements were applied for comparison of physical capacity, cardiovascular outcomes and maternal temperature.

Results: VO2 max and physical fitness were higher in both groups in the second trimester, returning to basal levels in the third trimester. In both groups, CO increased as pregnancy progressed and peak exercise temperature was higher than resting temperature, increasing further after five minutes of recovery and remaining at this level until 15 minutes after exercise completion. There was no difference between the two groups regarding duration (457.9 ± SD 249.6 vs 428.9 ± SD 203.2 minutes) or type of delivery. Labor analgesia was requested by significantly fewer women in the water aerobics group (27% vs 65%; RR = 0.42 95%CI 0.23–0.77). Neonatal results were similar in both groups.

Conclusion: The regular practice of moderate water aerobics by sedentary and low risk pregnant women was not detrimental to the health of the mother or the child. There was no influence on maternal cardiovascular capacity, duration of labor or type of delivery; however, there were fewer requests for analgesia during labor in the water aerobics group.

BioMed Central
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Reproductive Health
Open AccessResearch
Water aerobics in pregnancy: cardiovascular response, labor and
neonatal outcomes
Erica P Baciuk1, Rosa I Pereira*2, Jose G Cecatti1, Angelica F Braga2 and
Sergio R Cavalcante
1
Address: 1Department of Obstetrics and Gynecology, School of Medical Sciences, University of Campinas (UNICAMP), Sao Paulo, Brazil and 2Department of Anesthesiology, School of Medical Sciences, University of Campinas (UNICAMP), Sao Paulo, Brazil
Email: Erica P Baciuk - ericaxba@terra.com.br; Rosa I Pereira* - rosa@fcm.unicamp.br; Jose G Cecatti - cecatti@unicamp.br;
Angelica F Braga - franklinbraga@terra.com.br; Sergio R Cavalcante - cccavalcante@terra.com.br
* Corresponding author
Abstract
Background: To evaluate the association between water aerobics, maternal cardiovascular
capacity during pregnancy, labor and neonatal outcomes.
Methods: A randomized, controlled clinical trial was carried out in which 34 pregnant women
were allocated to a water aerobics group and 37 to a control group. All women were submitted
to submaximal ergometric tests on a treadmill at 19, 25 and 35 weeks of pregnancy and were
followed up until delivery. Oxygen consumption (VO
2 max), cardiac output (CO), physical fitness,
skin temperature, data on labor and delivery, and neonate outcomes were evaluated. Frequency
distributions of the baseline variables of both groups were initially performed and then analysis of
the outcomes was carried out. Categorical data were compared using the chi-square test, and
numerical using Student's t or Mann-Whitney tests. Wilk's Lambda or Friedman's analysis of repeat
measurements were applied for comparison of physical capacity, cardiovascular outcomes and
maternal temperature.
Results: VO
2 max and physical fitness were higher in both groups in the second trimester, returning
to basal levels in the third trimester. In both groups, CO increased as pregnancy progressed and
peak exercise temperature was higher than resting temperature, increasing further after five
minutes of recovery and remaining at this level until 15 minutes after exercise completion. There
was no difference between the two groups regarding duration (457.9 SD 249.6 vs 428.9 SD
203.2 minutes) or type of delivery. Labor analgesia was requested by significantly fewer women in
the water aerobics group (27% vs 65%; RR = 0.42 95%CI 0.230.77). Neonatal results were similar
in both groups.
Conclusion: The regular practice of moderate water aerobics by sedentary and low risk pregnant
women was not detrimental to the health of the mother or the child. There was no influence on
maternal cardiovascular capacity, duration of labor or type of delivery; however, there were fewer
requests for analgesia during labor in the water aerobics group.
Published: 21 November 2008
Reproductive Health 2008, 5:10 doi:10.11861742-4755-5-10Received: 8 August 2008
Accepted: 21 November 2008
This article is available from: http:www.reproductive-health-journal.comcontent5110
2008 Baciuk et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http:creativecommons.orglicensesby2.0
),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Background
Women's lifestyles and their repercussions in pregnancy
and delivery have been the subject of much debate, the
principal concerns being that exercise may interfere with
fetal-placental demands, increasing the risk of teratogenic
abnormalities or of compromising fetal development or
growth 1.
Today, women are encouraged to practice regular physical
activity as part of a healthy lifestyle. Many women already
practice regular aerobic conditioning or strength-building
exercise prior to becoming pregnant. Others view preg-
nancy as an opportunity to change their lifestyle by intro-
ducing more healthy habits. However, physicians have
traditionally counseled their patients who practice exer-
cise to reduce exercise levels during pregnancy and have
discouraged sedentary women from initiating an exercise
program at this time 2.
If there are still doubts on the safety of practicing general
physical activity during pregnancy, there is also a com-
mon recognition that the activity performed in water is
safer. Exercise in water promotes a redistribution of body
fluids that leads to an increase in central blood volume
and cardiac output, mainly due to a secondary increase in
stroke volume. On the other hand, blood pressure and
heart rate decrease. However, these changes do not affect
any parameter of fetal well-being 3.
Recommendations such as those of the American College
of Obstetricians and Gynecologists (ACOG) defend the
practice of regular, moderate physical activity even for
sedentary expectant mothers or for those with slight com-
plications such as gestational diabetes. Absolute and rela-
tive contraindications to the practice of exercise must,
nevertheless, be respected, including for instance multiple
gestation, higher risk of premature labor, incompetent
cervix, bleeding during pregnancy, severe heart diseases,
fetal growth restriction, and others 4.
Common sense indicates that high intensity activities
andor high impact activities should be avoided since the
practice of exercises such as these may expose the mother
and fetus to unnecessary risks such as mechanical trauma,
restricted development or prematurity 4. On the other
hand, moderate exercise in water presents several advan-
tages since it does not overload the muscular-skeletal
structure, reduces edema and prevents an increase in
maternal skin temperature 1. In other words, the ideal
heart rate calculated for the intensity of the exercise
should be adapted to 60 to 90% of one's age predicted
maximum heart rate 2,4. The use of RPE (Ratings of Per-
ceived Exertion) is recommended in both the American
1 and Canadian 2 guidelines for the intensity evalua-
tion during pregnancy. In fact, Artal & Toole 1 states thattarget heart rates cannot be used to monitor exercise
intensity in pregnancy due to variability in maternal heart
rate responses to exercise. Davies et al. 2 suggests the use
of a modified version of the conventional age-corrected
heart rate target zone but also the use of Borg's scale is sug-
gested.
Reports in the literature show that the interrelationship
between physical exercise and pregnancy is complex. The
results of the published studies are controversial, and
there are few randomized, controlled clinical trials that
evaluate the effects of moderate physical activity in water
on pregnancy and delivery 5-7. A recent randomized
controlled study showed no differences regarding gesta-
tional ages between women practicing or not regular exer-
cises during pregnancy 8
The objective of this study was to evaluate the association
between the practice of water aerobics during pregnancy
and maternal cardiovascular capacity, experience at deliv-
ery and neonatal outcomes among low risk pregnant
women who performed water aerobics compared to those
without exercise.
Methods
Participants and Design
Pregnant women of 20 weeks of pregnancy, who were
carrying a single fetus, had no gestational risk factors, were
receiving prenatal care at this institution and intended to
give birth there, were admitted to a randomized, control-
led clinical trial. The expectant mothers were provided
with information on the objectives of the study, as well as
information regarding the possible benefits of practicing
exercises during pregnancy, evaluations and procedures
that would be carried out in the research protocol. Those
who agreed to participate gave their signed, informed con-
sent and answered a questionnaire designed to evaluate
their physical fitness at admission. The principles of the
Helsinki Declaration were upheld and the research project
received the approval of the IRB of the institution
(Woman's Hospital of the School of Medical Sciences
from the University of Campinas in Brazil) prior to initia-
tion.
Exclusion criteria comprised: to practice regular physical
exercise; to have had two or more Cesarean sections, clin-
ical andor laboratory diagnoses of neurological, cardio-
vascular, pulmonary, muscular-skeletal or endocrine
disorders, and to have any disorder that could represent a
risk to the woman's health, such as morbid obesity, severe
anemia or vaginal bleeding during pregnancy.
Volunteers were enrolled sequentially and randomized to
one of the two study groups. Each sequential number cor-
responded to a sealed opaque envelope containing the

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information on the randomization group, according to a
previously prepared computer-generated randomization
list of numbers, in order to guarantee the concealment.
Water aerobic group was the one in which participants
would practice exercise, while Control group comprised
women who would not carry out any regular physical
activity during the entire pregnancy.
The intervention was the regular, moderate practice of
water aerobics for 50 minutes three times a week in an
indoor swimming pool with water warmed at 2830C.
Water aerobics was initiated following the first physical
evaluation and continued up to delivery. The moderate
intensity of exercises during the sessions was assured by
monitoring patients' heart rate using a heart rate monitor
2 and kept around 70% of one's predicted maximun
heart rate 4.
Evaluations
All pregnant women were submitted to three physical
evaluations during pregnancy: a control evaluation (prior
to initiating the practice of water aerobics at 1820
weeks of pregnancy); in the second trimester of pregnancy
(between 22 and 26 weeks), and in the third trimester of
pregnancy (between 32 and 36 weeks).
Maternal cardiovascular capacity was evaluated by a sub-
maximal endurance test, according to Bruce's modified
protocol II 9, a multistage treadmill test of graded exer-
cise. The test starts at 2.7 kmhour with no gradient. After
three minutes the inclination of treadmill increases to
10% in the same speed. At three minute intervals the gra-
dient is increased by 2% and the speed to 4 and 5.5 km
hour. The mean time for the patient to reach exhaustion
point is estimated to be 12 minutes. Prior to each test,
weight, height and women' vital signs (heart rate, resting
systolic and diastolic blood pressure) and fetal heart rate
were recorded. Next, the pregnant woman was placed on
an ergometric treadmill to record basal or control data:
ECG print-out, heart rate, blood pressure and maternal
skin temperature. During the ergometric test, women were
monitored using an integrated computerized ergometric
system (APEX TEB 2200) and submitted to the protocol
described above.
The test was designed to stop if one of the following
events occurred: exhaustion, significant alterations in
heart rate, electrocardiogram or skin temperature, or diffi-
culty in accompanying the set speed without running.
After completing the ergometric test, the woman was
requested to walk for 3 minutes at a speed of 2.7 kmhour
at 0% elevation so as not to cease the exercise abruptly.
Blood pressure was measured by the auscultatory method
at the end of each stage of exercise and up to 6 minutes
following exercise, using a mercury column sphygmoma-nometer. Skin temperature, in C, was measured prior to
exercise (at rest), at peak exercise, and at 5, 10 and 15 min-
utes following completion of exercise (recovery), using a
digital cutaneous thermometer. Fetal heart rate was mon-
itored using a portable fetal heart monitor (DF-25 Med-
cir) at rest, and at 10 and 15 minutes of recovery.
Endurance tests were always carried out at the same time
of the day, in a cool, well-ventilated room.
The study investigators were informed when any woman
was hospitalized for delivery, and were present to follow
up the labor and delivery and to collect data. The medical
team that provided care during delivery had no knowl-
edge of the randomization group of the individual
patient.
Baseline variables were: maternal age, body weight, pre-
gestational body mass index (BMI) (it was estimated
dividing the pre-gestational weight value informed by the
woman by the square height), parity, previous abortions
and Caesarean sections, and maternal education level.
Outcome measures
Maternal-dependent variables were defined as: cardiovas-
cular capacity and skin temperature. Cardiovascular
capacity was evaluated by the maximum oxygen con-
sumption (VO
2), by cardiac output in L.min-1 and by the
metabolic equivalent (MET). The equation for VO
2 (ml
kgmin) is speed 0.1 + (gradient100 1.8) + 3.5 and
all these parameters were directly obtained from the inte-
grated computerized system used. Secondary variables
were heart rate (HR), in beats per minute and blood pres-
sure in mmHg. Fetal-dependent variable was fetal heart
rate (FHR).
Variables regarding labor and delivery that were consid-
ered were: the woman's request for analgesia, cervical dila-
tion at the time of analgesia indication, length of labor
and types of delivery. Cervical dilation (cm) at analgesia
indication was measured by the obstetrician at the time at
which analgesia was given. The duration of labor (min-
utes) was calculated from the onset of regular uterine con-
tractions to delivery and was obtained from the delivery
records. Types of delivery were defined as spontaneous
vaginal delivery, forceps delivery, or Cesarean section.
Dependent variables for the newborn were obtained from
information on the obstetrics and neonatal records: birth
weight in grams, gestational age in weeks at delivery, and
vitality of the newborn, defined as the set of organic func-
tions of the newborn evaluated at the first and fifth min-
utes of life according to the Apgar Score.
Discontinuation criteria were defined as: any change that
could put the health of the mother or the fetus at risk;
irregular prenatal care; or the woman giving up the water

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aerobics sessions or any evaluation, but their data were
included in the final analysis because an intention-to-treat
analysis approach was chosen.
Analysis
Calculation of sample size was based on the difference
between the mean VO
2 max and cardiac output measured
at two different moments in the control and water aero-
bics groups in a study carried out by Prevedel et al. 5. For
the comparison of initial and final intra-group variables,
a sample size of 12 would be sufficient, and for the inter-
group comparison of variables, a sample size of 30 in each
group would be required 10,11. Sample size was
increased by around 20% to compensate for subject non-
compliance or for lost-to-follow-up, making a total of 71
expectant mothers, with a power of 80% and a type I error
of 0.05.
The information collected on the case report forms was
transferred to a database using the Epi Info software pro-
gram, version 3.2.2. Frequency distributions of the base-
line variables of both groups were analyzed to verify their
comparability and to exclude confounding factors. Analy-
sis of the dependent variables was then carried out in both
groups.
In the bivariate analysis, the qualitative variables were
compared using the chi-square test, and the numerical
variables using Student's t-test or the Mann-Whitney test.
Wilk's Lambda, corresponding to the multivariate analysis
of variance (MANOVA), was used for the comparison of
means of numerical variables with repeat measurements
or, in the case of non-normal data, Friedman's analysis of
repeat measurements was applied. The Epi Info software
program, version 3.2.2 and the SAS program, version 8.2
were used in all analysis procedures.
Results
Participants
Of the 78 expectant mothers eligible for inclusion in this
trial, 34 were randomized to the water aerobics group and
37 to the control group, while 7 women were excluded
before randomization, one because of morbid obesity,
two because admission ultrasonography revealed abnor-
malities (one fetal malformation and one fetal death) and
four because they considered too difficult to follow the
program of water aerobics (Figure 1). Baseline characteris-
tics of the 71 participants are shown in Table 1. Physical
evaluations were carried out on average at: 19 weeks
(first), 25 weeks (second) and at 35 weeks of pregnancy
(third).
Maternal outcomes
The indicators of maternal cardiovascular capacity were
similar in the two groups throughout pregnancy (Figure2). VO
2 max and physical capacity (MET) were greater
during the second trimester; returning, however, in the
third trimester to values similar to those measured at the
beginning of pregnancy. Cardiac output increased as preg-
nancy progressed.
HR was also similar in both groups. HR measured at rest
showed a significant increase from the second to the third
trimester. HR measured during exercise decreased from
the second to the third trimester of pregnancy, reaching
values lower than those registered at the first evaluation
(Figure 3).
Systolic blood pressure showed time and group effects. In
the water aerobics group, systolic blood pressure
remained unaltered from the first to the second trimester
of pregnancy and increased in the third, while in the
group of control women, first there was a reduction in val-
ues, followed by an increase. Peak exercise systolic blood
pressure showed lower values at the second evaluation
and increased at the third evaluation, returning to values
close to rest (Figure 3). Flow chart of the study Figure 1
Flow chart of the study.

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Diastolic blood pressure was similar throughout preg-
nancy in the two groups. There was a marginal reduction
in resting measurements between the first and the second
evaluations and an increase at the third evaluation. Peak
exercise diastolic blood pressure behaved similarly to
peak exercise systolic pressure (Figure 3).
There were no statistically significant differences in mater-
nal skin temperature in either group over the three evalu-
ations. Peak exercise values were greater than resting
values, increasing at 5 minutes of recovery and remaining
unaltered up to 15 minutes of post exercise recovery (Fig-
ure 4).
Labor outcome
There were no statistically significant differences in the
duration of labor between the two groups or in the type of
delivery. However, significantly fewer women in water
aerobics group (27.3%) than in control group (64.9%)
requested analgesia, which was initiated in women of
both groups at approximately 6 7 cm of cervical dilation
(Table 2). This represented a 58% reduction in the risk of
having analgesia requested (RR = 0.42; 95%CI 0.23
0.77). Even controlling for parity and level of schooling,
this difference in requesting analgesia remained highly
significant (data not shown in table).
Fetal and neonatal outcomes
There was no statistically significant difference in pre-exer-
cise FHR in the water aerobics group compared to the con-
trol group, and values decreased as the pregnancies
evolved. FHR increased during maternal exercise at the
first and second evaluations and remained at this level at
10 and 15 minutes following completion of exercise in
both groups. In the third trimester, a difference was
observed between the groups. In the water aerobics group,
FHR increased at 10 minutes, decreasing at 15 minutes of
recovery. In the control group, FHR increased only at 15
minutes following completion of maternal exercise (Fig-
ure 5).Neonatal results were similar in both groups and are also
shown in Table 2. Mean birth weight was 3.222 grams and
mean gestational age was 39 weeks for water aerobics
group while respectively 3312.7 g and 39.1 weeks for con-
trol group. The majority of newborns obtained Apgar
scores 7 in the first minute in both groups, while all of
them obtained scores 7 at the fifth minute.
Discussion
The current study found that there was no effect on the
cardiovascular capacity of the women or on the duration
of labor or the type of delivery for women practicing water
aerobics regularly during pregnancy in comparison to
those not practicing exercise at all. However, fewer
women in the exercise group requested analgesia.
Most of the knowledge available today on the practice of
physical exercise during pregnancy is based on longitudi-
nal and, mainly, observational studies. This randomized
controlled trial may contribute towards greater compre-
hension of the interaction between pregnancy and the
practice of water aerobics, as well as the repercussions of
exercise in labor and on the well-being of the newborn
infant.
Cardiovascular parameters of VO
2 max, cardiac output
and submaximal endurance heart rate showed similar
results in both groups, showing that the practice of water
aerobics according to the regimen described in this study
failed to have any effect on physical capacity. These results
are in agreement with data published by Prevedel et al.
6.
VO
2 max and physical capacity (MET) increased during
the second trimester of pregnancy and returned to previ-
ous values during the third for both groups, while Wolfe
et al 12 reported an increase in VO
2 max with the pro-
gression of pregnancy in women who participated in a
program of physical conditioning, while values remained
unchanged in a group of sedentary pregnant women, but
Table 1: Clinical characteristics of expectant mothers according to group.
VariablesWater Aerobics Control
n = 34 n = 37
Age (years)25.8 4.6 24.4 5.8
Weight (kg)63.8 12.7 60.8 10.2
Pre-gestational BMI 24.1 4.5 23.4 3.8
% of nullipara47.1 (16) 62.2 (23)
% with previous abortions 20.6 (7) 10.8 (4)
% with previous C section 11.8 (4) 24.3 (9)
% with only primary school education 47.1 (16) 27.0 (10)
Continuous data are expressed by means standard deviation.
Differences not statistically significant using Student's t or 2 tests as appropriate

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VO2max, cardiac output and metabolic equivalent at the three evaluation moments, according to group Figure 2
VO
2max, cardiac output and metabolic equivalent at the three evaluation moments, according to group.
30 35 40 45 50
15 20 25 30 35 40VO2 max - Exercise (mLkgmin)
Weeks of Gestation
10 12 14 16 18 20
15 20 25 30 35 40
Cardiac Output- Exercise (Lmin)
Weeks of Gestation
7 8
9 10
11
12
13
14
15 20 25 30 35 40Physical Capacity - Exercise (METs)
Weeks of Gestation
Water Aerobics GroupControl Group

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Heart rate, systolic and diastolic pressure at the three evaluation moments, according to group Figure 3
Heart rate, systolic and diastolic pressure at the three evaluation moments, according to group.
60 80 100 120 140 160 180 200
15 20 25 30 35 40
Heart Rate - (beatsmin)
Weeks of Gestation
80 100 120 140
160
180
15 20 25 30 35 40
Systolic Blood Pressure - (mmHg)
Weeks of Gestation
60 65 70 75
15 20 25 30 35 40Diastolic Blood Pressure - (mmHg)
Weeks of Gestation
Water Aerobics RestingControl Group RestingWater Aerobics ExerciseControl Group Exercise

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Maternal skin temperature at the three evaluation moments, according to group Figure 4
Maternal skin temperature at the three evaluation moments, according to group.
35 36 37 38
0 5 10 15 20
Temperature (C)
minutes
resting
peak

resting
35 36 37
38
0 5 10 15 20
Temperature (C)
minutesrestingpeak

35 36 37 38
0 5 10 15 20
Temperature (C)
minutes
Water Aerobics GroupControl Group
restingpeak

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evaluations were made using ergometric bicycles. Santos
et al. 13 reported a substantially increase in submaximal
exercise capacity in overweight pregnant women who
were submitted to aerobic exercise sessions also in a rand-
omized controlled trial.
The increase in resting heart rate over the course of preg-
nancy was an expected result and may be explained by a
reduction in vagal parasympathetic control. The smaller
increase in heart rate during exercise in the third trimester
of pregnancy may be a result of the reduction in the
response to sympathetic stimulation during pregnancy
14,15.
The maintenance or reduction of systolic blood pressure
in the second trimester and reduction of diastolic blood
pressure confirm that the response of arterial blood pres-
sure during pregnancy is related to a reduction in periph-
eral vascular resistance 16-18. At the second evaluation,
the lower value of diastolic blood pressure during exercise
may be a result of the lower response to sympathetic stim-
ulation. The expected effect of vascular pumping caused
by the balance between vasoconstriction of the non-active
musculature versus vasodilatation of the active muscula-
ture may not be sufficiently adapted to overcome the
present reduction in peripheral vascular resistance. This
preloading reduction may consequently lead to a post-
loading reduction and lower systolic blood pressure,
which was probably compensated by an increase in the
ventricular contractility during exercise at the beginning
of pregnancy 18,19. The rise in systolic blood pressure
during exercise in the third trimester showed an adequate
adjustment in the pressure-volume curve at acute endur-
ance.
These results show that the pregnant women had an ade-
quate adaptive response to the demands of a normal preg-
nancy. Moreover, they were capable of compensating for
greater demands such as an endurance test or the practice
of regular, moderate physical activity in water despite the
fact that no effect was obtained on cardiovascular condi-
tioning during pregnancy.The reduction in fetal heart rate with the progression of
pregnancy may be directly related to the immaturity, par-
ticularly parasympathetic immaturity, of the autonomous
fetal nervous system in the first half of pregnancy. The
increase in FRH observed during recovery may be
explained by the liberation of maternal catecholamines
during physical exercise, confirmed by the increase in
maternal HR 20. However, in the third trimester, the
group that practiced water aerobics appeared to show a
more adequate autonomic response than the control
group. Probably this response accompanies the reduction
in the maternal response to sympathetic stimulation dur-
ing this period of pregnancy 15,18.
Van Doorn et al. 21 described an increase in FHR five
minutes after maternal peak exercise. Veille et al. 22)
reported no change in FHR during 30 minutes following
moderate maternal exercise. Carpenter et al. 23 also
failed to find any significant differences in FHR at rest and
5 minutes following maternal peak exercise.
To avoid possible side effects of maternal-fetal hyperther-
mia, endurance tests were always carried out at the same
time of the day, in the same environmental conditions
and in a cool, well-ventilated room, in order to minimize
the increase in skin temperature of the volunteers. The
acceptable maternal skin temperature of approximately
38.9C was respected 24.
Maternal temperature increased in response to strenuous
exercise and remained high in both groups until 15 min-
utes following the end of exercise, causing no ill effects to
fetal vitality as can be seen from the response in FHR.
These results are in agreement with data published by
Soultanakis-Aligianni 24 who described an increase in
maternal temperature during exercise of approximately
0.7C and 0.4C at 20 and 32 weeks of pregnancy, respec-
tively. This increase found in skin temperature was lower
for the cases studied by Larson & Lindqvist 25 and
Lindqvist et al.26 and one possible explanation refers to
the fact that these authors measured the core temperature
instead skin temperature. The difference between skin and
Table 2: Characteristics of labor, delivery and neonatal outcomes according to group.
Variables Water aerobics Control P
Request for analgesia n (%) 9 (27.3) 24 (64.9) 0.004**
Length of labor (min)a457.9 249.6 428.9 203.2 0.69*
C-section n (%) 12 (36.4) 17 (45.9) 0.57**
Birth weight (g) 3222.2 562.7 3312.7 656.1 0.54*
Apgar Score 1
st minute 7 (%) 97 94.6 0.54**
Gestational age (weeks) 39.2 2.2 39.1 1.6 0.73*
Continuous data are expressed by means standard deviation.
* Student's t-test ** 2 Yates a Only for vaginal deliveries

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Fetal heart rate at the three evaluation moments, according to group Figure 5
Fetal heart rate at the three evaluation moments, according to group.
120 130 140 150 160 170 180 190
0 5 10 15 20Fetal Heart Rate (beatsmin)
resting
minutes

120 130 140
150
160 170 180 190
0 5 10 15 20
Fetal Heart Rate (beatsmin)
resting
minutes

120 130 140
150
160
170
180
190
0 5 10 15 20
Fetal Heart Rate (beatsmin)
Water Aerobics GroupControl Group

resting
minutes

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core temperature might be interpreted as a safety mecha-
nism during pregnancy exercise. This would give a possi-
ble explanation to the trend towards increased skin
temperature in the exercise group.
Some limitations of the current study could be pointed
out. Probably the most important refers to the practical
difficulty of maintaining a high compliance with the
water aerobics program. Although these women had free
access to the swimming pool and professional oriented
sessions of water aerobics, plus the costs for transport
three times per week, around one third of them discontin-
ued the program during pregnancy due to logistic and
family constraints, including job restrictions, care of chil-
dren and home affairs.
The results of this study show that the regular practice of
moderate water aerobics during pregnancy by low risk
women who were previously sedentary is not detrimental
to the health of the mother or the child. Although there
was no effect on the cardiovascular capacity of the expect-
ant mothers, on the duration of labor or the type of deliv-
ery, fewer women in the water aerobics group requested
analgesia, probably because of better psycho-physical
condition. Clap III 27, who studied women that prac-
ticed physical activity and who either continued or spon-
taneously stopped exercising (control group) in the first
trimester of pregnancy, observed similar results. This
author observed a lower incidence of Cesarean sections,
shorter duration of labor, a greater number of vaginal
deliveries, and less need for epidural anesthesia among
women who continued exercising during pregnancy.
Moreover, infants born to women in the exercise group
were smaller and had higher Apgar scores at the first
minute.
Neonatal results from this present study confirm the well-
being of the newborn infants born to mothers who initi-
ated regular physical activity in water during pregnancy.
Therefore this kind of exercise could be recommended to
mothers willing to practice any physical activity during
pregnancy 27. The babies had adequate weight, gesta-
tional age and vitality at birth, confirming the trend that
already exists in the literature that moderate, regular phys-
ical activity has no influence on prematurity or on the
weight of the newborn infant. However, the adequacy of
the exercise has to be assured since the practice of physical
activity that is rigorous either in its intensity, duration or
frequency is associated with low neonatal birthweight
5,28-33.
Conclusion
The regular practice of moderate water aerobics by low
risk and previously sedentary expectant mothers offers no
risk to the health of the mother or the child. Althoughthere was no effect on the cardiovascular capacity of the
women or on the duration of labor or the type of delivery,
fewer women in the exercise group requested analgesia.
Abbreviations
ACOG: American College of Obstetricians and Gynecolo-
gists; BMI: body mass index; CO: cardiac output; ECG:
electrocardiogram; FHR: fetal heart rate; HR: heart rate;
MANOVA: multivariate analysis of variance; MET: meta-
bolic equivalent; RR: Risk ratio; VO
2 max: oxygen con-
sumption.
Competing interests
The authors declare that they have no competing interests.
Authors' contributions
EPB, RIP and JGC participated in all steps of the study,
including research planning, data collection, analysis and
writing the manuscript. AFB participated in the project
planning and review of the manuscript. SRC participated
in data collection and review of the manuscript. All
authors gave suggestions, read the manuscript carefully,
fully agreed on its content and approved its final version.
AcknowledgementsThis study was partially funded by FAEPEX (Fundo de Apoio ao Ensino,
Pesquisa e Extenso) from the University of Campinas (UNICAMP), grant
97302.
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