GDM: Medical Nutrition Therapy (2016)

Vinter CA, Jørgensen JS, Ovesen P, Beck-Nielsen H, Skytthe A, Jensen DM. Metabolic effects of lifestyle intervention in obese pregnant women. Results from the randomized controlled trial 'Lifestyle in Pregnancy' (LiP). Diabet Med. 2014 Nov; 31 (11): 1,323-1,330. doi: 10.1111/dme.12548. Epub 2014 Jul 23. PMID: 24989831 PubMed ID: 24989831
Study Design:
Randomized Controlled Trial
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Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
To investigate whether lifestyle intervention during pregnancy could improve the metabolic status and subsequently improve pregnancy outcomes in obese women.
Inclusion Criteria:
Women were included in the study if:
  • Obese (BMI of 30 to 45kg/m2, calculated from pre-pregnancy weight or first measured weight in pregnancy)
  • Aged 18 to 40 years
  • Pregnant and between 10 and 14 weeks of gestation
  • Danish-speaking
  • Single pregnancy
  • Without major medical disorders (including pre-gestational diabetes)
  • Without previous serious obstetrical complications
  • Did not abuse alcohol.
Exclusion Criteria:
Women were excluded from the study if:
  • BMI not between 30 and 45kg/m2
  • Did not meet age requirements (less than 18 years or older than 40 years)
  • Gestation at referral was greater than 14 weeks
  • Had prior serious obstetric complications
  • Had major medical disorders (including pre-gestational diabetes)
  • Did not speak Danish
  • Abused alcohol
  • Current pregnancy was multiple.
Description of Study Protocol:


Women were recruited to the study after referral to the Department of Gynecology and Obstetrics and meeting inclusion requirements.


  • In this non-blinded randomized controlled trial (RCT), after providing written consent eligible women were randomized to one of two arms: Intervention or control
  • Throughout their pregnancy, the intervention group received four separate diet counseling sessions and an exercise program (consisting of weekly aerobic classes, free fitness membership and exercise motivating initiatives)
  • Physical activity levels and eating habits were self-reported by both the intervention and control groups at baseline and at 35 weeks gestation
  • A brief fitness test (the Danish step test) was performed at baseline and at the last visit before delivery to measure physical fitness
  • Both study groups were monitored throughout pregnancy using fasting blood samples, oral glucose tolerance tests (OGTT), sonar fetal biometry and measurements of maternal weight and blood pressure.

Blinding Used

This was a non-blinded RCT.


  • The intervention group received four separate diet counseling sessions and an exercise program (consisting of weekly aerobic classes, free fitness membership and exercise motivating initiatives).
  • Dietary counseling was performed by trained dietitians on four separate occasions, at 15, 20, 28 and 35 weeks gestation, with the aim of limiting gestational weight gain to five kg
  • The counseling included dietary advice based on the official Danish recommendations
  • Energy requirements for each participant were individually estimated according to weight and level of activity (Vinter et al, 2011).

Statistical Analysis

  • Between-group differences were analyzed using the chi-squared test; the student T-test and the Mann-Whitney U-test were also used for continuous variables
  • Sub-analyses were done according to the IOM gestational weight gain recommendations using ANOVA or chi-squared test
  • The Wilcoxon rank-sum test was used for a power calculation (85% power). 
Data Collection Summary:

Timing of Measurements

  • Blood samples were collected at the gestational age of 12 to 15 weeks (used as baseline measurement), at 28 to 30 weeks and at 34 to 36 weeks
  • A fitness test was done at baseline and at the last visit before delivery. 

Dependent Variables

  • Gestational weight gain (kg; calculated as weight at 35 weeks of gestation minus weight measured at recruitment)
  • Two-hour OGTT (mmol per L)
  • Fasting insulin (mU per L)
  • HOMA-IR (homeostasis model assessment of insulin resistance)
  • Fasting cholesterol (mmol per L)
  • Fasting HDL (mmol per L)
  • Fasting LDL (mmol per L)
  • Fasting triglycerides (mmol per L)
  • Systolic blood pressure (mmHg)
  • Diastolic blood pressure (mmHg)
  • VO2max (ml kg-1 min-1).

Independent Variables

Improved diet and increased physical activity, however modifications or goals for dietary and physical activity changes were not specified by study authors.

Description of Actual Data Sample:
  • Initial N: 360 women
  • Attrition (final N): 150 women in the intervention group; 154 women in the control group
  • Age: 29 years (27 to 32) for the intervention group; 29 years (26 to 31) for the control group
  • Ethnicity: Danish, Caucasian
  • Other relevant demographics: Subjects were evenly matched as: Smokers; primiparous; at least 12 years of school; at least three years of further education; and in gainful employment
  • Anthropometrics: Maternal BMI was evenly matched between groups; 33.4kg/m2 (31.7 to 36.5) for the intervention group; 33.3kg/m2 (31.7 to 36.9) for the control group
  • Location: Denmark.
Summary of Results:

Key Findings

  • The intervention group had significantly lower gestational weight gain compared with the control group (7.4±4.6kg vs. 8.6±4.4kg, P=0.01)
  • There were no significant differences in clinical outcomes for pre-eclampsia or pregnancy-induced hypertension, gestational diabetes, Cesarean section, large for gestational age and admission to the neonatal intensive care unit
  • There were no significant differences in fasting cholesterol, LDL, HDL, trigylceride levels, systolic and diastolic blood pressures between groups
  • VO2 max was signficantly higher in the invention group at 34 to 36 weeks gestation compared to the control group (23±5 vs. 22±4, P=0.049)
  • There was no difference in the rate of women diagnosed with gestational diabetes between intervention and control groups (6.0% vs. 5.2%, P=0.760)
  • Women in the intervention group had a significantly lower change in fasting insulin from randomization to 28 weeks gestation compared with the control group (3.1±4.9mU per L vs. 4.3±4.9mU per L, P=0.015)
  • Increase in insulin resistance (HOMA) was lower in the intervention group compared with control subjects at 28 to 30 weeks gestation (0.7±1.3 vs. 1.0±1.3, P=0.022)
  • At 34 to 36 weeks gestation, insulin resistance was higher in the control group, although not statistically significant.

Other Findings

  • Compliance with exercise classes was low: 56% of women in the intervention group attended the aerobic classes for at least half of the sessions
  • 92% of subjects in the intervention group completed all four dietetic counseling sessions and 98% completed at least three sessions
  • 85% of the women in the intervention group responded affirmatively that participation in the study resulted in more healthy eating habits
  • Self-reported leisure time physical activity level was significantly improved in the intervention group
  • Spending at least two hours per week with leisure time physical activities making them break sweat or be short of breath increased from 29% to 56% during pregnancy. For the control group, physical activity level decreased from 34% to 25% and the difference in the third trimester was statistically significant (P<0.001).
  • 20% of women in the control group reported that they believed their participation in the study in itself had improved their lifestyle despite no active intervention. 
Author Conclusion:
  • Lifestyle intervention during pregnancy could restrict gestational weight gain and limit the physiological increase in insulin resistance during pregnancy
  • The intervention did not significantly affect clinical obstetric outcomes, overall oral glucose tolerance test results or lipid profiles between groups. 
Funding Source:
University/Hospital: The Faculty of Health Sciences; University of Southern Denmark
The Novo Foundation; The Danish Medical Association Research Foundation; The Danish Diabetes Association; The Health Insurance Foundation
Foundation associated with industry:
Reviewer Comments:
  • Changes to dietary intake and physical activity were all self-reported by study subjects
  • The authors make an interesting observation: Women in the control group were as motivated as those in the intervention group. They state that the control group could be characterized as a "passive intervention group" and the crossover from the control group could explain the small differences between groups, underestimating the potential effect of the intervention.
  • In addition, due to subject drop-out, the power was reduced to 77%
  • Description of the dietary counseling sessions by the dietitians and details about the counseling was not listed in this article but was referenced in this study by the same authors: Vinter CAJensen DMOvesen PBeck-Nielsen HJørgensen JS.The LiP (Lifestyle in Pregnancy) study: a randomized controlled trial of lifestyle intervention in 360 obese pregnant women. Diabetes Care. 2011 Dec; 34 (12): 2,502-2,507.
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? 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.) 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? ???
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? ???
  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? ???
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? No
  6.6. Were extra or unplanned treatments described? No
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? ???
  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