GDM: Medical Nutrition Therapy (2016)


Korpi-Hyovalti E, Schwab U, Laaksonen DE, Linjama H, Heinonen S, Niskanen L. Effect of intensive counselling on the quality of dietary fats in pregnant women at high risk of gestational diabetes mellitus. Brit J Nutr. 2012. 108: 910-917. 

PubMed ID: 22093485
Study Design:
Randomized Controlled Trial
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
To evaluate the effect of an intensive dietary therapy on quality of diet, weight gain and birth weight in women at high risk of gestational diabetes mellitus (GDM). 
Inclusion Criteria:
One or more risk factors
  • BMI over 25kg/m2
  • Previous history of GDM or birth of child over 4.5kg
  • Aged over 40 years
  • Family history of diabetes (parents, children, siblings or grandparents)
  • Venous plasma glucose concentration after 12 hours overnight fasting was 4.8mmol to 5.5mmol per L and the two-hour oral glucose tolerance test plasma glucose less than 7.8mmol per L
  • Gestational week eight to 12.
Exclusion Criteria:
GDM during weeks eight to 12 of gestation.
Description of Study Protocol:
  • Recruitment: First contact at maternal health care unit between April 2005 and May 2006
  • Design: RCT
  • Blinding used: Health care nurses who scheduled the study visits did not have access to the randomization list.


  • Intervention group received dietary advice six times during pregnancy vs. the control group, which received close follow-up in a community-based setting
  • Intervention group recieved a nutritritionist-tailored individual diet four times in first and second trimesters and twice in the third trimester
  • Diet goal: 50% to 55% CHO, 30% fat (more than 10% SFA) and 15% to 20% protein, with a minimum of 15g dietary fiber
  • Women were encouraged to eat a diet rich in vegetables, berries and fruits, and to use fat-free and low-fat dairy products, low-fat meats, soft margarines and vegetable oils (primarily low-erucic acid rapeseed oil), and whole-grain products
  • Energy intake was 126kJ per kg per day for normal-weight women and 105kJ per kg per day for overweight women
  • The women received information about the goals of eating, demands of pregnancy, meals and snacks, amount of food, supply of fibe, and amount and quality of fats by the nutritionist
  • The Three-Factor Eating Questionnaire was used in the beginning of pregnancy and at weeks 36 to 40
  • The baseline four-day (four consecutive days, one weekend day) food record was completed before the first appointment at weeks eight through 12, checked by the nutritionist and formed the basis for dietary advice during the first session
  • The food record procedure was repeated before the fifth appointment at weeks 26 to 28 and the sixth appointment at weeks 36 to 40.

Statistical Analysis

  • Repeated-measures ANOVA for Three-Factor Eating Questionnaire and weights
  • PUFA analyzed using the student's T-test and corrected using the Bonferroni method
  • Student's T-test for continuous variables and X2 or Fisher's exact test for categorical variables
  • The use of spread was analyzed by the McNemar test.
Data Collection Summary:

Timing of Measurements

  • Four-day food records at baseline and at fifth and sixth appointments at weeks 26 to 28 and 36 to 40, respectively
  • Oral glucose tolerance (OGTT) at baseline
  • Three-Factor Questionnaire at beginning of pregnancy and at weeks 36 to 40.

Dependent Variables

  • GDM: 75g, two-hour OGTT at weeks eight to 12
  • Changes in diet: Four-day food records analyzed using Nutrica software
  • Gestational weight gain
  • Infant birth weight.

Independent Variables

  • Intervention: Clinical nutritionist-tailored diet six times during pregnancy
  • Controls: General information given by an RN on diet and physical activity in a single session.
Description of Actual Data Sample:
  • Initial N: 60 women
  • Attrition (final N): 54
  • Age: Not described
  • Ethnicity: Not described
Other Relevant Demographics
Anthropometrics (e.g., were groups same or different on important measures)
  • There were no significant differences between groups with regards to weight, BMI, educational status, energy or percentage of calories from macronutrients
  • Control group had a significantly lower percentage of calories from linolenic acid compared to intervention group (P=0.4)
  • Location: Finland.
Summary of Results:


  • At weeks 26-28, three women were classified as having GDM in the intervention group and one in the the Close Follow-Up Group
  • No differences between the groups in the Eating Questionnaire at the beginning and end of pregnancy. There was also no effect of intervention except for a slight tendency toward additional cognitive restraint in the Lifestyle Intervention Group.
  • Intake of PUFA increased significantly in the intervention group during pregnancy (P=0.008) and on average met the recommendations. PUFA intake was statistically significant greater at the end of pregnancy (P=0.045). There were no clear differences in the changes of SFA or fiber intake between the groups. 
  • Use of vegetable oil-based spread increased significantly during pregnancy in the intervention group (P=0.003). No statistically significant difference in the quality of the spread on bread during pregnancy was found in the Close Follow-Up Group. 
  • Intervention group had a somewhat lower weight gain (P=0.062), compared to the Close Follow-Up Group
  • Mean birth weight was greater in the intervention group as compared with the close follow-up group (3,871g vs. 3,491g; P=0.047). There was no difference in the gestational age nor in macrosomia between the two groups.
  • There were no signficant differences in serum lipids, serum thyroid stimuating hormone or serum-free-thyroxin between the two groups.
Author Conclusion:
Individualized counseling by a clinical nutritionist as part of a lifestyle intervention improved the quality of dietary fat intake in pregnant women at high risk of GDM. 
Funding Source:
University/Hospital: Kuopio University Hospital, Central Hospital of Finland, Seinajoki Central Hospital, University of Eastern Finland
Reviewer Comments:
The article mentioned that three women in intervention and one in close follow-up were classified as having GDM at 26 to 28 weeks, however there was no description of determining this.
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) No
  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? No
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? No
  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.) N/A
  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? Yes
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  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? N/A
  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? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? Yes
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