GDM: Calories (2016)


Ho L, Benzie IFF, Lao TT. Relationship between caloric intake and pregnancy outcome in diet-treated gestational diabetes mellitus. Nursing & Health Sci. 2005; 7:15-20.

PubMed ID: 15670002
Study Design:
Prospective Cohort Study
B - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
To examine the relationships between the following:
  1. Estimated and prescribed caloric intake
  2. Estimated caloric intake and short-term glycemic control assessed using the post-prandial blood glucose profile
  3. Estimated caloric intake and long-term control using gestational weight gain as the surrogate. 
Inclusion Criteria:
  • Chinese women with gestational diabetes mellitus (GDM)
  • Within 90% to 120% of ideal body weight
  • Prescribed caloric intake was 30kcal per kg
  • Could speak and understand Cantonese
  • Singleton pregnancy
  • No other complications.
Exclusion Criteria:
  • Pre-existing DM
  • Underlying medical complications requiring dietary restriction or control
  • Multiple pregnancies.
Description of Study Protocol:

Women with GDM were recruited at the time of their first blood glucose profile assessment in the day ward following commencement of diet therapy

Prospective observational. After diagnosis of GDM, women who had completed a five-day dietary survey were recruited into the study. The women were categorized by their mean calorie intake over the five days into tertiles for comparison of gestational weight gain, glycemic control and pregnancy outcome. 

Blinding Used


Statistical Analysis

  • Continuous variables were analyzed with the T-test and one-way ANOVA method, with post-hoc analysis by Duncan's multiple range test, set at the 5% level
  • Categorical variables were analyzed by the chi-squared test and Spearman's correlation coefficient.
Data Collection Summary:

Timing of Measurements

Five days, starting one week after seeing a dietitian.

Dependent Variables

  • Glycemic control: OGTT and glucose following breakfast, lunch and dinner
  • Pregnancy outcome: Weeks of gestation, birthweight, crown heel length, Apgar score at one minute and five minutes, large-for-gestation age (LGA) percentage, small-for-gestational (SFA) percentage and placental weight
  • Pregnancy weight gain: Difference between the immediate pre-delivery and recalled pre-pregnancy weight for whole pregnancy and weight gain following diagnosis was the difference between immdiate pre-pregnancy weight and weight at OGTT. 

Independent Variables

Caloric intake: Five-day self-recorded food diary using hand and fist size to estimate portion. Five days covered a weekend and the day prior, to the third day following the blood glucose profile (fasting and two hours after breakfast, lunch and dinner). 

Description of Actual Data Sample:
  • Initial N: 88 females
  • Attrition (final N): 62
  • Age: 34.6 to 35.1 years (plus or minus 2.7 to 4.9 years)
  • Ethnicity: Chinese
  • Anthropometrics: BMI and pregnancy weight gain were similar between three tertiles of average estimated total caloric intake
  • Location: Hong Kong.
Summary of Results:


  • Caloric intake in the highest tertile was the only mean caloric intake that was close to the prescribed
  • There was no significant difference in fasting or two-hour glucose values or gestational age at OGTT. For glucose profile, no difference was found in the post-breakfast or post-lunch glucose concentrations, but the post-dinner (P<0.02) and mean post-prandial glucose concentrations (P<0.05) were significantly higher in the highest tertile group. Partial correlation and controlling for pre-pregnancy weight and height demonstrated a significant correlation between mean caloric intake with post-dinner glucose concentration (P<0.012), but not for mean post-prandial glucose concentration. 
  • There was no significant difference between caloric intake tertiles in gestational age, birthweight, crown heel length, Apgar scores at the first and fifth minute, incidence of LGA or SGA infants or the placental weight. Neither the incidence of LGA nor SGA infants correlated significantly with caloric intake.
Author Conclusion:
  • Neither the post-prandial blood glucose profile nor gestational weight gain in non-obese gestational diabetic women managed with diet therapy necessarily reflect their actual caloric intake
  • There was a tendency for the patients to over-restrict their intake and the prevalence of SGA infants was unexpectedly high. Nevertheless, the results also suggest that apart from the incidence of SGA infants, the perinatal outcome remained satisfactory as long as the caloric intake did not exceed that prescribed. 
Funding Source:
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? N/A
  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? Yes
  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? N/A
  4.1. Were follow-up methods described and the same for all groups? N/A
  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? N/A
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  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? ???
  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? 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? No
  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? Yes
  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? ???
  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? No
  7.7. Were the measurements conducted consistently across groups? N/A
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)? 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