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


Morse JM, Ewing G, Gamble D, Donahue P.  The effect of maternal fluid intake on breast milk supply:  a pilot study.  Canadian Journal of Public Health. 1992 May-Jun; 83(3): 213-216. 

PubMed ID: 1525748
Study Design:
Randomized crossover trial
A - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

To examine the effect of increased and decreased fluids on breast milk supply.

Inclusion Criteria:
  • Women had previously breast fed
  • Normal delivery of healthy full-term exclusively breast-fed infant
  • Married
  • Healthy
  • Non-smoking
  • Unemployed
  • Educated
  • Willing to adhere to a similar diet throughout study
  • Not taking prescription medications (including oral contraceptives)
  • Breastfeeding at discrete intervals throughout day.
Exclusion Criteria:

Not reported.

Description of Study Protocol:


Ongoing recruitment throughout data collection phase of study.


Randomized crossover study.


Randomized crossover assignment to treatment groups for three days each:

  • Treatment A:  normal (monitored) fluid intake based on maternal body weight (40ml per kg+750ml for lactation loss per day)
  • Treatment B:  50% reduction of recommended fluid intake (20ml per kg+750 ml for lactation loss per day)
  • Treatment C:  50% increase over recommended intake (60ml per kg+750ml for lactation loss per day).

Statistical Analysis

Repeated measures analysis of variance.

Data Collection Summary:

Timing of Measurements

Pre-study (two weeks to three weeks postpartum)

  • Recruitment
  • Enrollment
  • Instructions to mothers for test-weighing, measuring regurgitated milk, expressing milk with pump, measuring fluid intake, keeping diet records and collecting/storing urine samples.

Begin study (infants 24 days to 32 days of age, lactation well-established)

  • Three days before initial data collection: prescribed normal fluid intake (A)
  • Data collection began after first morning feed on days four, 12 and 20 and stopped after early-morning feed at beginning of study days seven, 15 and 23. 
  • Five days between each treatment during which moms were given two days off (no treatment) followed by three days normal intake (A). 
  • Data collection for each subject extended over 23 days.

Dependent Variables

  • Milk volume (infant intake; expressed milk samples; regurgitated and leaked milk collection; breast pads weighed)
  • Infant milk intake (test weighing)
  • Urine volume (24-hour urine)
  • Urine specific gravity (24-hour urine)
  • Water and caloric content of food/beverages (diet record).

Independent Variables

Amount of fluid consumed by mother: Treatment A (normal), Treatment B (decrease), Treatment C (increase)

Control Variables

Duration of exposure to "treatment"; timeline of measurements/data collection during study.

Description of Actual Data Sample:


Initial N: 20 mother-infant pairs

Attrition (final N): 50%, 10 mother-infant pairs 

Age: 22 years to 35 years (mean 29.4 years)

Ethnicity: Not reported

Other relevant demographics: Mean parity 2.2; 3.6 years post-secondary education

Anthropometrics: Not reported

Location: Faculty of Nursing, Clinical Sciences, University of Alberta, Alberta, Canada.

Summary of Results:



A - Normal

B - Decrease

C - Increase

Statistical Significance of Group Difference

Breast Milk Yield (g) Treatment Day Three (% change from A)


756.8 (-3.5%)


Not reported

3-day Mean (% Change from A)


714.6 (-3.0%)

742.6 (+<1.0%)


 No significant effect of treatment on milk production.


Author Conclusion:

Although milk supply increased with increased fluid intake and decreased with decreased fluid intake, this change was not statistically significant.

Funding Source:
Reviewer Comments:

Very small sample; did not use mother's usual fluid intake as a baseline; did not consider cited  target population (those with or suspecting insufficient milk syndrome, IMS), or perceived notion of IMS.

Unclear how many women started the study. Article states 10 pairs were recruited; states 50% attrition rate; gives data for N=10 women. Assume study then would have started with 20 pairs.

Data from urine samples and diet records not reported.

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? No
  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? No
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? No
  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? ???
  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? ???
  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? No
  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? 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? Yes
  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? ???
  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? ???
  7.6. Were other factors accounted for (measured) that could affect outcomes? No
  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)? No
  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? ???
  8.7. If negative findings, was a power calculation reported to address type 2 error? No
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