GDM: Physical Activity (2008)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To describe the relationship between exercise during the last trimester of pregnancy and physiologic outcomes of mothers and newborns to determine whether differences exist between active and sedentary exercise patterns on these variables.
Inclusion Criteria:

1.  Primiparous women, 20 to 30 years of age

2.  >32 weeks gestation

3.  Classification of physically active by Physical Activity Index questionnaire that listed activities conducive to cardiovascular endurance.  Those participating in activities for at least 15 to 30 minutes 3 times per week were considered to be active.  

 

Exclusion Criteria:
No preexisting medical conditions.
Description of Study Protocol:

Recruitment:  Convenience sample drawn from private obstetric practices, Lamaze classes, solicited through fliers and by verbal invitation

Design: Case-Control Study.

Blinding used (if applicable):  Not described

Intervention (if applicable):  

1.        Subjects completed Physical Activity Index (PAI) developed by authors to measure active and sedentary exercise patterns.  Women indicated which activities they participated in from a check list and the average # of times per week that they participated in the activity.  Participants were instructed to check an activity only if they participated in that activity for at least 15 - 30 minutes.  Women indicating that they participated in an activity 3 or more times per week were classified as active.  Otherwise, women were classified as sedentary.

2.        Completed questionnaire to collect demographic information: race, marital status, education level, age, cesarean birth

3.        Completed checklist of common discomforts of pregnancy.  After delivery, participants were also interviewed regarding any additional discomforts.

4.        Hospital records reviewed to obtain data:   wt gain, length of gestation, length of labor, Apgar scores, and birth weight

Stastical Analysis:  Proportions were compared with chi-square analysis and t-tests for independent samples were used to compare means.  Pearson correlations were used to investigate the relationship betwen the mothers' exercise patterns and Apgar scores of the vaginally delivered newborns.  An alpha level of p< .01 was used to establish statistical significance and to control for the increased risk of type 1 error due to use of multiple significance testing.

Data Collection Summary:

Timing of Measurements:  Questionnaires completed at time of initial interviews.  After delivery, participants interviewed to ascertain additional discomforts.  Hospital records reviewed to ascertain weight gain, lenght of gestation, length of labor, Apgar scores and birth weight.

Dependent Variables:

  • Weight gain
  • Weeks of gestation
  • Length of labor
  • Common discomforts of pregnancy, including headache, nausea/vomiting, vaginal discharge, frequent urination, swelling, sleep disturbances, leg cramps, fatigue, shortness of breath, heartburn, constipation, hemorrhoids, clumsiness, lightheadedness
  • Occurrence of cesarean section
  • Birth Weight
  • Apgar Scores

Independent Variables:

  • Activity in last trimester of pregnancy

Control Variables:

Description of Actual Data Sample:

Initial N: 101 primiparous women, 48 active and 53 sedentary, all greater than 32 weeks gestation;  In the sedentary group, 47 of the women reported no regular physical activity performed for at least 15 continuous minutes.  Of the 48 women categorized as active, 14 reported the minimum of 3 activities per week performed for at least 15 continuous minutes, where as 28 reported five or more such activities.

Attrition (Final N): None described

Age: Active 28.4 + 4.1, Sedentary 27.2 + 3.8

Ethinicity:  Predominantly white

Other relevant demographics:  Convenience sample,  married and well educated.

Anthropometrics:  Not reported

Location:  Greenville, NC

Summary of Results:

Characteristics of Women in the Sedentary and Groups differed only with respect to Educational Level, with 38% of active women with post bachelor's education compared with 9% in the sedentary group  (see table below):

Abbreviated Table of Descriptive Characteristics between Sedentary and Active Women

 

Sedentary

n = 53

Active

n=48

X2

Educational Level

n (%)

n (%)

12.64*

High School

8 (15)

6 (12) 

 

Some College

19 (36)

11 (23) 

 

BA/BS

21 (40) 

13 (27) 

 

Post Bachelor

5 (9)

18 (38)

 

*p < .01

Variables including race, marial status, cesarean birth rate and age were similar.

Activity:  47% of the active group reported brisk walking as their chosen activity, with the next most popular activities being aerobic dance and swimming, both of which were reported by less than 10% of the participants.

Commom discomforts of pregnancy as reported by the two groups are seen in the table below.  The Sedentary group reported a significantly greater incidence of vaginal discharge as compared to the vaginal group.  Although none of the other discomforts differed significantly between the two groups, 25% of the active group reported 5 or fewer discomforts, compared with only 6% of the sedentary group (X2>7.45,  p<.01).  Comparing discomforts such as swelling, leg cramps, fatigue and shortness of breath, which the authors felt were most likely to be affected by exercise, 44% of the active group reported having only 1 or 2 of those discomforts compared with 21% of the sedentary group (X2=6.15,  p=.01).

Incidence of Common Discomforts in the Sedentary and Active Group

 

Variable

Sedentary

N = 53

Active

N = 48

X2

 

n(%)

n(%)

 
Headache 18 (34) 18 (38) 0.03
Nausea/Vomiting 22 (42) 18 (38) 0.04
Vaginal Discharge 42 (79) 25 (52) 7.15*
Frequent Urination 50 (94) 46 (96) 0.00
Swelling 42 (79) 34 (71) 0.56
Sleep Disturbances 41 (77) 33 (69) 0.56
Leg Cramps 38 (72) 25 (52) 3.34
Fatigue 48 (91) 35 (73) 4.22
Shortness of breath 36 (68) 26 (54) 1.47
Heartburn 38 (72) 25 (52) 3.34
Constipation 28 (53) 19 (40) 1.28
Hemorrhoids 17 (32) 16 (33) 0.00
Clumsiness 23 (43) 20 (42) 0.00
Lightheadedness 15 (28) 17 (35) 0.31

 *p < .01

With respect to outcome measures, no significant differences were found between the two groups on mean weight gain during pregnancy, infant birth weight, gestational age, or number of significant discomforts.  For participants delivering vaginally, no differences were found with respect to time spent in the various stages of labor or Apgar scores at 1 minute.  The mean Apgar score at 5 minutes was significantly higher for the newborns of the women in the secondary group, although all scores were above 7.

Finally, those mothers with the greater number of reported physical activities tended to have newborns with lower Apgar scores at 1 and 5 minutes, demonstrating a significantly negative correlation between vaginal delivery and total number of phyisical activities (r=-.32 at 1 minute; re = -.47 at 5 minutes).

 

Author Conclusion:

The differences found in Apgar scores at 5 minutes were of little significance given that all scores were above 7 and the clinical variability that occurs with the assignment of apgar scores.

Overall, women in the sedentary group were found to have more discomforts than the women in the active group, especially those discomforts of vaginal discharge, swelling, leg cramps, fatigue, and shortness of breath.  The authors suggest that exercise may be a factor in promoting a general sense of well-being and in reducing discomforts frequently associated with pregnancy.  On the other hand, it is possible that as pregnancy symptoms increase, women may shy away from exercise.

May have been subject bias in reporting physical activity.

Subjects may have misinterpreted terms on pregnancy checklist.

Recall of up to 3 months occurred at times and this may have affected those discomforts reported.

Funding Source:
University/Hospital: East Carolina University
Reviewer Comments:

While these results suggest little difference on select pregnancy outcomes between women who are active or sedentary in the 3rd trimester, the limitations of the measures make interpreting and using the results difficult.

The use of the PAI to measure physical activity presents some challenges.  Measurement of the intensity of physical activity was not done and the time frame of 15 to 30 minutes is too wide of a range.   Further, the authors do not name all of the activities listed on the PAI and refer to these activities as "sufficiently active to stress the cardiovascular system" which is too vague, especially given that 28 of the active women indicated that they engaged in 5 or more of these activities weekly which seems rather high.   From the authors description it cannot be discerned whether the active participants spent time engaged in running, swimming, cycling, walking and aerobics vs gardening, light housework, walking, etc.  It is also not clear how the authors handled women who may have cross trained, participating in multiple high intensity activities, but doing so for only 1 or 2 days per week, for instance perhaps a participant ran twice a week, swam twice a week and cycled twice a week, engaging in a total of 6 days per week of high intensity activity, but engaging in each activity only twice per week.   It would have been helpful had they used a validated and reliable measure of physical activity.

Also, the authors indicate that the pregnancy checklist was piloted, but later report the possibility of misinterpretation by participants on the symptom variable which was found to be different between the two groups as well issues related to recall.  These issues should have been addressed prior to data collection, or once discovered these data sets should have been removed from the analysis.  Additional subjects could have been used if power was an issue.

Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) N/A
 
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? No
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) Yes
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? ???
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? ???
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) ???
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? ???
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? N/A
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? Yes
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? ???
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? No
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? No
  7.1. Were primary and secondary endpoints described and relevant to the question? ???
  7.2. Were nutrition measures appropriate to question and outcomes of concern? N/A
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? No
  7.5. Was the measurement of effect at an appropriate level of precision? No
  7.6. Were other factors accounted for (measured) that could affect outcomes? No
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  8.6. Was clinical significance as well as statistical significance reported? N/A
  8.7. If negative findings, was a power calculation reported to address type 2 error? No
9. Are conclusions supported by results with biases and limitations taken into consideration? No
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? No
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes