EAL

GDM: Medical Nutrition Therapy (2016)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

Through an intervention based on social learning theory, to:

Improve dietary intake during pregnancy
Optimize gestational weight gain, glycemic levels and birth weight
Avoid unnecessary postpartum weight retention.

Inclusion Criteria:

All Cree women if they were:

Receiving prenatal services prior to 26 weeks' gestation
Without pre-gestational diabetes
Recruited between July 1995 and January 1997.

Exclusion Criteria:

Only women with pre-gestational diabetes.

Description of Study Protocol:

Recruitment

Women recruited between July 1995 and March 1996 served as controls. Women recruited between April 1996 and January 1997 were in the intervention group.

Design

Participants were seen by the dietitian during the control period for dietary evaluations at 24 to 30 weeks' gestation and at six weeks post-partum. Data on weight gain and glucose values were collected by clinic staff following routine procedures. Two research nutritionists lived and worked in two communities during the control and intervention periods. The nutritionists received training in cultural beliefs concerning diet, developed and adapted local teaching aids and worked with a team of healthcare workers, including a community nutritionist working in the Cree villages. Cree health workers were hired in each of the four communities. A baseline questionnaire was used for demographic information, brief pre-natal history and smoking habits. Dietary data were determined from 24-hour recalls at 24 to 30 weeks' gestation and at six weeks post-partum. Participants were compared with non-participants living in their communities at the same time.

Intervention

The intervention was based on social learning theory; strategies used included modeling, skill training, contracting and self-monitoring. Activities included local radio broadcasts about healthy eating in pregnancy; pamphlets about nutritional choices and encouraging breastfeeding; supermarket tours and cooking demonstrations; exercise/walking groups; and individual counseling. Dietary advice was related to improving the intake of dairy products and fruits and vegetables, while decreasing the intake of high-energy foods with little nutritional value and staying within guidelines for weight gain during pregnancy.

Statistical Analysis

Independent T-tests were used to compare:
- Mean nutrient intakes
- Birth weight
- Birth weight ratio
- Gestational age
- Rate of weight gain
- Glycemic level on the glucose screen
- Post-partum weight retention.
Log transformation was used to normalize:
- Pre-gravid weight
- Body mass index
- Post-partum weight.

Data Collection Summary:

Timing of Measurements

24-hour dietary recalls were obtained at 24 to 30 weeks' gestation and at six weeks post-partum. Physical activity was also measured via questionnaire at the time of the dietary recalls. Measurement of weight during pregnancy was not described by authors. Post-partum weight was measured at six weeks' post-partum. Oral glucose screen test conducted between 24 and 30 weeks of gestation.

Dependent Variables

Dietary intake during pregnancy (determined by 24-hour recall)
Gestational weight gain (calculated from 20 weeks until delivery)
Glycemic levels (measured by 50g oral glucose screen test)
Birth weight (obtained from medical chart)
Post-partum weight retention (measured weight at six weeks post-partum minus pre-gravid weight).

Independent Variables

Nutritionists and Cree health workers used social learning theory strategies (modeling, skill training, contracting and self-monitoring) to provide:

Local radio broadcasts about healthy eating in pregnancy
Pamphlets about nutritional choices and encouraging breastfeeding
Supermarket tours and cooking demonstrations
Exercise/walking groups
Individual counseling.

Control Variables

Participants were compared with non-participants living in their communities at the same time.

Description of Actual Data Sample:

Initial N: 323 pregnant women
Attrition (final N): 200 pregnant women (96 in control group, 104 in intervention group)
Age: 23.8 years (±5.86) for the control group, 24.3 years (±6.29) for the intervention group
Ethnicity: Members of the Cree community
Other relevant demographics: Groups were fairly matched on:
- Gestational age at entry (18.5±6.92 weeks for control group; 17.1±7.06 weeks for intervention)
- Number of smokers (42% for control group, 52% for intervention group)
- Parity
  - Zero: 37% for control group and 31% for intervention group
  - One: 26% for control group and 28% for intervention group
  - Two to four: 35% for control group and 34% for intervention
  - More than four: 2% for control group and 7% percent for intervention group.
Anthropometrics: Groups were fairly matched on pre-pregnancy:
- Weight (78.9±17.54kg for control group, 81.0 ± 19.46kg for intervention group)
- Height (163.2±5.71cm for control group, 162.0±5.04cm for intervention group)
- Body mass index (29.6±6.45kg/m² for control group, 30.8±6.85kg/m² for intervention group)
Location: Cree communities of James Bay, Quebec, Canada.

Summary of Results:

Key Findings

The intervention did not result in differences in diet measured at 24 to 30 weeks gestation
There was no significant difference in rate of weight gain over the second half of pregnancy (0.53±0.32kg for the control group vs. 0.53±0.27kg for the intervention group)
There was no significant difference in plasma glucose level (50g oral glucose screen) between 24 and 30 weeks (7.21±2.09mmol per L for the control group vs. 7.43±2.10mmol per L for the intervention)
Mean birth weights were similar between groups (3,741±523g for the control group vs. 3,686±686g for the intervention group)
Maternal weight at six weeks post-partum was also similar (88.1±16.8kg for the control group vs. 86.4±19.0kg for the intervention group)
The only significant change in diet was a reduction in caffeine during pregnancy (P<0.05).

Author Conclusion:

The intervention did not succeed in changing dietary intake, weight gain or plasma glucose levels among pregnant Cree women.

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?	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?	???
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.)	No
	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?		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.)	No
	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?	Yes
	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?	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