ORP: Structured Programs and Interventions (2014)

Citation:

Jeffries K, Shub A, Walker SP, Hiscock R, Permezel M. Reducing excessive weight gain in pregnancy: A randomised controlled trial. Med J Aust. 2009:Oct 19; 191(8): 429-433. 

 

PubMed ID: 19835535
 
Study Design:
Randomized Controlled Trial
Class:
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To assess the effect on total weight gain during pregnancy of a personalized gestational weight-gain recommendation (based on early pregnancy BMI) and regular weight measurement. 

Inclusion Criteria:
  • Pregnant women
  • Age more than 18 years and less than 45 years
  • Singleton pregnancy
  • English speaking
  • Written informed consent obtained.
Exclusion Criteria:
  • Age less than 18 years or more than 45 years
  • Type 1 or type 2 diabetes mellitus
  • Multiple pregnancy
  • Non-English speaking.
Description of Study Protocol:

Recruitment

Recruited by the student researcher at their woman's first antenatal appointment in the outpatient clinic at or before 14 weeks gestation.

Design

Randomized controlled trial.

Blinding Used

Participants were blinded to the purpose of the study.

Intervention 

  • Participants were seen at recruitment and at 36 weeks gestation
  • All women enrolled received standard antenatal care
  • All women were weighed at their first antenatal appointment using balance-beam scales, but standard antenatal care did not involve further routine weight measurement
  • All participants completed two previously validated questionnaires about eating habits and energy expenditure in the 12 months before pregnancy and the first trimester of pregnancy
  • Intervention group also received:
    • Optimal gestational weight-gain range for their pregnancy, defined by their BMI and the IOM guidelines for weight gain during pregnancy
    • Ideal weight range, together with their weight as measured at recruitment, was recorded on a personalized weight-measurement card
    • Participants were told to record their own weight at 16, 20, 24, 28, 30, 32 and 34 weeks gestation, using either a tabular or graphical format provided on the measurement cards
    • Weight measurements during pregnancy were done on either the participants’ own scales at home or those at the hospital, according to patient preference
    • Counseling was completed by medical student researcher.
  • Control group: Weighed at recruitment and at 36 weeks gestation, but were not given any further advice regarding optimal weight gain or regular weighing.

Statistical Analysis

  • Sample size was set for a power of 0.8 to show a weight difference of 2kg between the control and intervention groups. A sample size of 192 women (96 in each group) was required.
  • Two-sided Fisher’s exact test was used for numerical data
  • Independent two-samples T-test or the Wilcoxon rank-sum test for continuous variables were used according to their distribution
  • Sub-group analysis based on BMI categories was also performed for weight gain per week, and the proportion of participants exceeding IOM guidelines
  • Stata (version 10, StataCorp, College Station, Tex, USA) was used
  • Data were analyzed on an intention-to-treat basis
  • Statistical significance was defined as (two-sided) P≤0.05
  • Bonferroni correction was used to adjust for multiple comparisons in the sub-group comparisons.
Data Collection Summary:

Timing of Measurements

  • Study was completed between July 2007 and May 2008
  • Participants were weighed and completed questionnaires at recruitment and at 36 weeks gestation. 12 women had self-reported weights at the 36-week follow-up.
  • Obstetric records were reviewed after delivery.

Dependent Variables

  • Weight gain per week of observation
  • Proportion of women exceeding the IOM guidelines: For obese women, the number who exceeded 11.5kg were considered to be above the IOM guidelines, based on the upper limit assigned to overweight women.

Independent Variables

Counseling by medical student researcher on appropriate weight gain and encouragement to self-monitor weight during pregnancy.

Control Variables

Pregnancy outcomes.

 

Description of Actual Data Sample:

Initial N

  • Intervention: 148 women
  • Control: 138 women.

Attrition (Final N)

  • Intervention: 125 women (84.5% of initial cohort)
  • Control: 111 women (80.4% of initial cohort).
Anthropometrics

Mean weight at recruitment:
  • Intervention: 68kg±15.8kg
  • Control: 68kg±12.9kg

Location

Melbourne, Australia.

 

Summary of Results:

Key Findings

  •  Overall mean weight gain:
    • Intervention: 0.44kg±0.173kg per week
    • Control: 0.46kg±0.156kg per week
    • Mean difference of 0.02kg per week (95% CI0.02kg to 0.07kg per week).
  • Overall mean weight gain in the overweight group (BMI, more than 26.0kg/m2, 29.0 kg/m2 or less):
    • Intervention (N=20): 0.42kg±0.153kg per week
    • Control (N=18): 0.54kg±0.123kg per week
    • Mean difference of 0.12kg per week (95% CI: 0.03kg to 0.22kg per week; P=0.01).
  • Overall mean weight gain in underweight group (19.8kg/m2 or less):
    • Intervention (N=5): 0.44±0.104
    • Control (N=5): 0.47±0.098
    • Mean difference of 0.14 (95% CI: -0.00 to 0.29; P=0.06).
  • No significant differences between weight gain for participants classified as normal or obese
  • Number of women gaining more weight than the IOM-recommended amount:
    • Intervention: 23 of 125 (18%)
    • Control: 26 of 111 (23%)
    • Fisher’s exact test, P=0.42.

Other Findings

  • No significant differences in obstetric or neonatal outcomes between the intervention and control groups
  • No clinically meaningful differences between the women in the control and intervention groups in terms of demographic characteristics:
    • Age
    • Smoking status
    • Parity
    • Marital status
    • Educational attainment.
Author Conclusion:

Our study shows that if overweight women are made aware of their personalized recommended weight gain and encouraged to monitor and record their weight change over their pregnancy, excessive gestational weight gain may be reduced. 

Funding Source:
University/Hospital: University of Melbourne, Melbourne, VIC; Mercy Hospital for Women, Melbourne, VIC
Reviewer Comments:
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) Yes
 
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? Yes
  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.) Yes
  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.) N/A
  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? Yes
  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? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? Yes
  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.) Yes
  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? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  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? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  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? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  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)? Yes
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? Yes
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
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