BF: Dietary Factors, Breast Milk and Infant Outcomes (2008)


Dusdieker LB, Stumbo PJ, Booth BM, Wilmoth RN. Prolonged Maternal Fluid Supplementation in Breast-Feeding. Pediatrics.1990; 86: 737-740.

PubMed ID: 2235228
Study Design:
Randomized Crossover Trial
A - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

Evaluation of the effect of prolonged maternal fluid supplementation on the milk supply of breastfeeding women.

Inclusion Criteria:

19 well-nourished women whose infants were solely breast fed and thriving were enrolled when their infants were 90 days to 120 days of age.

Exclusion Criteria:

These criteria were not delineated.

Description of Study Protocol:

The project was approved by the University Committee on Research Involving Human Subjects.


Breastfeeding women-infant pairs were recruited from the Pediatric Child Health Clinic at the University of Iowa Hospitals and Clinics.


  • Randomized, crossover study design
  • Participants were randomly assigned to either study sequence 1 (three days of baseline fluids followed by seven days of 25% increased fluids) or study sequence 2 (seven days of 25% increase fluids followed by three days of baseline fluids).
  • Randomization was done using tables of random numbers within blocks of 10 to assure even allocation to the sequences throughout the duration of the study.


The 25% fluid supplement was given as water, with half of the daily supplement taken mid-morning and the remainder mid-afternoon.

Statistical Analysis

  • Paired T-tests and analysis of variance procedures for a crossover design were used to compare total milk production between baseline and increased fluid study sections.
  • Linear and multiple regression techniques were used to investigate other interactions of milk volume and fluid intake.
  • The sample size was large enough to detect a 25% difference in milk volume between study sections with a power of 80%.

Data Collection Summary:

Timing of Measurements

Milk production was measured on days two and three of baseline fluids and days six and seven of increased fluids.  


  • Mother's weight: The participants were weighed and measured by nursing personnel at the initial clinical research center visit. During the initial diet-recording period, research personnel delivered an Egnell electric breast pump and Pennsylvania infant scale to each participant's home, calibrated the scale in the stationary location and then taught the mother how to operate the scale.
  • Infant's weight: The mother and research assistant each performed several test weighings of the infant before and after feeding as a check of weighing accuracy. 
  • Mother's triceps skinfold thickness in the nondominant arm.

Dietary Assessments

  • The registered dietitian instructed the women in diet-recording techniques.
  • The women completed a three-day diet record of customary food and beverage intake.
  • Calculations of dietary water were made by multiplying the percentage of water in the food by food weight using published values.
  • The researchers used the initial three-day diet record as an example of baseline intake and a 25% increase in total dietary water (from food and beverage) was calculated.

Crossover Study

Each mother completed both study sections (baseline fluids and increased fluids). 

Dependent Variables

  • Total milk production (ml):
    • The women were instructed to weigh the infant before and after each feeding in the same clothing and diapers. Weights were double checked and recorded to the nearest 10g. After the infant finished nursing, the mother used the electric breast pump until milk stopped spurting from the nipple. The volume of expressed milk was measured in milliliters (one ml=one g). 
    • Women who were separated from there infants for a feeding were instructed to measure and record the volume of milk expressed by hand or breast pump. Women who leaked milk either between or during feedings were asked to wear reweighed, absorbent breast pads that were then stored in airtight containers in the refrigerator until reweighed. 
    • Milk production was measured on days two and three of baseline fluids and days six and seven of increased fluids. For each baseline or increased fluid section 48-hour milk production was calculated as the sum of the test weights plus the volume of milk expressed after nursing plus the amount of milk leaked into breast pads.
  • Calorie intake (kcal)
  • Specific gravity: Mothers were asked to collect a urine specimen before and one hour after each water supplement was consumed.

Independent Variables

25% fluid supplementation vs. baseline fluid

  • The women were asked to keep daily intake records of all food, beverage and water supplements consumed during the baseline and increased fluid sections of both sequences.
  • The 25% fluid supplementation was given as water, with half of the daily supplement taken mid-morning and the remainder mid-afternoon. Additional fluids in excess of the supplement were permitted if the mother desired.

Control Variables

  • Interaction between fluid intake and milk production
  • Effect of study sequence
  • The women were instructed to keep their physical activity consistent throughout the study duration.


Description of Actual Data Sample:

Initial N: 19 women

Attrition:  Zero

Age: 18 years or older. The mean age of the study women was 30.8y and five were primipara.

Ethnicity: White

Other relevant demographics: The subjects were married and well-educated (mean 16.75y of schooling).

Anthropometrics: Maternal measurements for mean height (162.5cm±5.5cm), mean weight (62.2kg±7.0kg), and mean triceps skinfold thickness (21.6mm) were within expected norms. The 11 baby boys and eight baby girls were similar in age and growing well. 

Location: University of Iowa Hospitals and Clinics.


Summary of Results:

Daily Dietary Intake and Milk Production (N=19)* 


Baseline Fluids

Increased Fluids

Total fluid intake(ml)



Fluid from food (ml)



Calorie intake (kcal)



Total milk production (ml)



 * Data are given as mean±standard deviation
  • No significant linear relationship was found between percentage increase in fluid intake and percentage change in milk production in excess of baseline.
  • The effect of study sequence was evaluated by three-way analysis of variance, controlling for order. No effect of sequence or order was found.
Author Conclusion:
  • Results were described for the compliant mothers only.
  • Mean daily milk production was 767ml±178ml for the baseline section and 744ml±138ml for the increased fluid section.
  • There was no significant change in milk production between baseline and increased fluid periods.
  • No significant change in milk production between baseline and increased fluid periods.
  • No significant linear relationship between the percentage increase in fluid intake and percentage change in milk production was found.
  • Limitation: The mothers of thriving breastfed infants in the study are a different population than the mothers of infants who fail to thrive with breastfeeding.
Funding Source:
Government: NIH
Reviewer Comments:
  • The randomized, crossover study is considered a powerful type of design to test which factors lead to certain outcomes when sample size is small.
  • The subjects were a representative sample of the relevant population.
  • Power calculation was done: The sample size was large enough to detect a 25% difference in milk volume between study sections with a power of 80%.
  • The researchers were thorough in their delineation of the results and data limitations.
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) ???
  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%.) N/A
  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.) N/A
  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? ???
  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? N/A
  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? N/A
  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? N/A
  7.6. Were other factors accounted for (measured) that could affect outcomes? N/A
  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? 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