GDM: Weight Management (2008)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To determine whether the risk of maternal overweight associated with an excessive rate of gestational gain needs to be balanced against the risks of impaired fetal growth associated with a low rate of gain.
Inclusion Criteria:
  • Young primigravidas and multigravidas 12-15 years of age at first pregnancy and more mature gravidas aged 19 and older at first pregnancy.
  • Normal pregravida weight: BMI range 19.8 to 26
Exclusion Criteria:
  • Serious health problems unrelated to pregnancy (lupus, diabetes mellitus, seizure disorders, malignancies, drug or alcohol abuse, psychiatric disorders)
Description of Study Protocol:

Recruitment

Cohort recruited between September 1985 and May 1990.

Design:  Cohort Study

Blinding Used (if applicable):  not applicable

Intervention (if applicable):  not applicable

Statistical Analysis

Association of measured rate of weight gain with maternal background characteristics was assessed using univariate statistics (chi-square tests and ANOVA).  Overall chi-square or F ratio was used to assess statistical significance.  When dependent variable was dichotomous, multiple logistic regression was used.  Odds ratios, adjusted for confounding variables, were computed from logistic regression coefficients and 95% confidence intervals from their covariance matrices.

Data Collection Summary:

Timing of Measurements

Rate of measured gestational gain taken at baseline, and women were followed up at 4-6 weeks and 6 months postpartum.

Dependent Variables:

    • Rate of gestational gain based on weights measured between 20-36 wk gestation with the rate representing the average (kg/wk) increments from 20-24, 24-28, 28-32, 32-34 and 34-36 wk.
    • Criteria: excessive gain: >0.68 kg/wk after wk 20; moderate weight gain: 0.34-0.68 kg/wk; low or inadequate wt gain: <0.34 kg/wk.
    • Postpartum weight retention at 4 to 6 wk and 6 mo postpartum (triceps, sub scapular, and suprailiac skin folds) and ht and weight.

Independent Variables

  • Dietary intake during pregnancy and postpartum

Control Variables

  • Age
  • Parity
  • Pregravid BMI
  • Height
  • Lactation
  • Cigarettes smoked
Description of Actual Data Sample:

Initial N:  321 women met criteria for study

Attrition (final N):  274 women were available for follow up studies

Age:  aged 12 - 29 years

Ethnicity:  Approximately 30% of the women were Puerto Rican/Hispanic and 60% were Black.

Other relevant demographics:  ~75% were on Medicaid

Anthropometrics:

Location:  New Jersey

Summary of Results:

Rate of weight gain

Maternal Factors Low Moderate High
  N=59 N=138 N=77

Pregravida BMI

22.2   22.2  22.1

Total weight

10.2 13.3    20.0

Gain (kg) 6 mos postpartum BMI

23.3  23.6  25.1

Skinfolds (sum, mm)

47.3  47.0   55.0

Neonatal Factors

     

Gestational Age (wk)

38.5  39.2 39.4

Birthweight (g)

3049 3208  3191

Other Findings

50.7% of those <15 yr of age gained excessive weight during pregnancy compared to 34.1% with moderate weight gain and 22% with low weight gain (P<0.05).

Women with low weight gain gave birth earlier and had lower birthweight babies (P<0.05).

Despite little difference in pregravid BMI, women with excessive rates of gain retained more weight overall, attained a greater postpartum BMI, and had higher levels of subcutaneous fat and overweight.

Maternal anthropometric status showed little change between 4-6 wk and 6 mos postpartum.

Author Conclusion:

Weight gained at an excessive rate by women with a pregravid BMI in the normal range does not greatly enhance fetal growth and duration of gestation, but instead, contributes to postpartum maternal overweight.

Weight gained during pregnancy by young teen women who are still growing may be easier to accrue and more difficult to lose postpartum than weight gained by a more mature individual as part of her pregnancy.  This weight may contribute, as well, to her long-term risk of chronic disease.

Funding Source:
Not-for-profit
0
Foundation associated with industry:
Reviewer Comments:

These findings are consistent with interpretations of the Institute of Medicine—that excessive weight gain results in greater postpartum weight retention.

Teenage women younger than 15 years of age may need greater intervention (WIC) to prevent excessive weight gain.

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) N/A
  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) N/A
 
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) N/A
  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.) N/A
  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? 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? Yes
  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? Yes
  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? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  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? N/A
  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)? 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