GDM: Monitoring (2008)

Citation:
 
Study Design:
Class:
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Quality Rating:
Research Purpose:

The purpose of this study was to examine the relationship of maternal acetonuria, weight loss, and low weight gain during pregnancy to the psychomotor performances and IQ values of neonates and older children of nondiabetic mothers.

Inclusion Criteria:

Infants born alive >20 wk gestation who were part of the Collaborative Project of the National Institute of Neurological and Communicative Disorders and Stroke.

Exclusion Criteria:

1. Major congenital malformations

2. Down’s syndrome

3.  Inborn errors of metabolism

4.  Head trauma during or after birth

5.  Lead intoxication in the child

6.  Either parent was mentally retarded.

7.  Mother had any of the following disorders:

8.  Hypothyroidism, convulsive disorder, diabetes mellitus, alcoholism.

Description of Study Protocol:

Recruitment:

Infants born alive >20 wk gestation from 53,518 pregnancies in the US were followed prospectively between 1959 and 1966 as part of the Collaborative Perinatal Project of the National Institute of Neurological and Communicative Disorders and Stroke to study pregnancy and long-term outcomes.

Design:

Cohort Study.  The effects of maternal acetonuria, weight loss, and low weight gain during pregnancy on children's psychomotor development and IQ were analyzed.

Blinding Used (if applicable):

Not applicable.

Intervention (if applicable):

Not applicable

Statistical Analysis:

Data was stratified by race, gestational age at birth, and a socioeconomic index which combined scores for education, occupation and family income. A value below 4 was considered to be low. Gestational age was calculated at birth from the start of the last menstrual period. Race was established by mother's self-identification. Acetonuria was recorded when the reading was 1+ or greater on one or more urine specimens examined during antenatal clinic visits and at admission for delivery.  The chi-square test, Student's t test, and the three-way F test with one-way analysis of variance were used.

Data Collection Summary:

Timing of Measurements:

Maternal acetonuria was measured during antenatal clinic visits and at admission for delivery.  Maternal weight gain was measured at the end of the pregnancy.  Infant/child psychomotor functions were measured during the neonatal period, at age 8 months, 1 and 4 years of age.  Children's IQ values were measured at 4 years of age.

Dependent Variables:

  • Children's IQ and psychomotor skills

Independent Variables:

  • Maternal acetonuria
  • Weight loss
  • Low weight gain during pregnancy

Control Variables:

  • Race
  • Socioeconomic status
  • Gestational age at birth

 

Description of Actual Data Sample:

Initial N:  53,518 pregnancies

Attrition (Final N):  not reported

Age:  maternal age not stated

Ethnicity:  Data was only reported for white women (self-reported)

Other Relevant Demographics:  None reported

Anthropometrics:  None reported

Location:  United States

Summary of Results:

Other Findings

In white women, neither gestational acetonuria, weight loss, nor low weight gain were associated with any consistent evidence of mental or motor impairments in offspring during the first year of life.

When compared to children whose mothers had weight gains of 22 to 32 pounds, children whose mothers lost weight during pregnancy failed 2 of the 7 tests at 4 yr of age more often.

Combining acetonuria with low weight gain or weight loss produced no consistent evidence of mental or motor impairments at any age.  As independent variables, neither acetonuria, low neither weight gain, nor pregnancy weight loss was associated with abnormal IQ values at 4 years of age.

Acetonuria, low maternal pregnancy weight gain, and pregnancy weight loss had no significant effect on IQ values and other measures of the psychomotor performance of black children.

Author Conclusion:

We found that maternal acetonuria, low weight gain, and weight loss during pregnancy had little or no effect on neonatal, infant and childhood psychomotor functions including IQ. These data were extracted from the same population used in the original study that claimed lower IQ values following acetonuria or Churchill and Berendes. Our results differ from those in the original study because we controlled for a number of nonnutritional factors that influence psychomotor development and IQ.

Ketone bodies are probably normally present to the fetal brain at various times during most pregnancies.  After an overnight fast, maternal ketone body concentrations are about threefold greater in pregnant than nonpregnant women. 

Funding Source:
Government: US Public Health Service
Reviewer Comments:

Weight loss during pregnancy appeared to have the most significant effect on psychomotor function of newborns and children. For example at 4 years if age, children born of women who lost weight failed 2 of 7 psychomotor tests (P<0.05, P<0.001). Also 2 of 14 psychomotor evaluations were significant in women who lost weight (P<0.0.05, P<0.01).  It is impossible in a cohort study to determine if weight loss caused acetonemia or if other factors related to poor dietary intake were the cause of abnormal psychomotor function tests.

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) 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? No
  4.1. Were follow-up methods described and the same for all groups? No
  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%.) No
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? ???
  4.4. Were reasons for withdrawals similar across groups? ???
  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? ???
  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.) ???
  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? ???
  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? 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? No
  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? ???
  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)? 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