Breast Versus Bottle Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Breast Versus Bottle Study (NCT03704051), a registered phase not stated study. The primary outcome is Infant Intake During the Observed Feeding (mL).

2. Clinical Question

The study’s stated objective is to assess how feeding mode affects the quality and outcome of infant feeding interactions. The registry identifies infant intake during the observed feeding as the primary outcome measure. It also says that, during bottle-feedings, investigators will note whether the infant finishes the bottle. The record does not report the result of that observation or identify it as the second outcome measure.

The comparison concerns feeding mode within the study’s observed visits; it is not a comparison of breastfeeding with a separate group that received no bottle-feeding. Because the registry does not report numerical primary outcome results, it is not possible to describe the direction or magnitude of an observed intake difference from this record.

3. Trial Design

The Breast Versus Bottle Study, registered as NCT03704051, is listed as completed. The registry lists a start date of 2018-10-15, a primary completion date of 2020-03-15, and enrollment of 94. California Polytechnic State University-San Luis Obispo is listed as the sponsor. The record describes the research as a within-subject experimental study of feeding mode and infant feeding interactions.

Both arm descriptions involve mother-infant dyads observed during breastfeeding and bottle-feeding expressed breast milk. In the arm called “Breastfeeding First, then Bottle-feeding,” the breastfeeding visit comes first and the bottle-feeding visit comes second. In the arm called “Bottle-feeding First, then Breastfeeding,” the visit order is reversed. Thus, the arm descriptions distinguish the sequence of observed feeding modes.

The registry states that allocation is not stated and cautions that the arms are not a like-for-like control comparison. It does not report that participants were randomly assigned to visit order. It also does not describe how the order was determined or whether order effects were assessed. These details matter because a within-subject comparison uses observations from the same dyad under both feeding modes, while the sequence may also be relevant to interpreting a contrast.

The primary outcome is infant intake during the observed feeding, measured in mL over a 2-hour period. The registry says intake is assessed through pre- and post-weighing the baby on an infant scale. It lists 2 outcome measures and 2 analyses, but does not identify the other measure or describe the analyses. No statistical analysis plan, analysis population, or numerical results for the primary outcome are reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: There were no significant events in the study (for example, wash out, run-in) that occurred after participant enrollment, but prior to the first within-subject condition.

Overall Study

Reasons for not completing this period:

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Population: Baseline analysis population included mothers (n = 47) and their healthy infants \<6 months of age (n = 47).

6. Primary Endpoint

The registry lists the primary outcome as Infant Intake During the Observed Feeding (mL), measured over 2-hour period.

The primary endpoint is infant intake during the observed feeding, expressed as a mean in mL. The registry gives a 2-hour period as the timeframe and describes measuring intake by weighing the baby before and after feeding on an infant scale. During bottle-feedings, the record also says investigators will note whether the infant finishes the bottle.

As a continuous outcome, intake can be described by its mean, which gives an average amount across the observations included in an analysis. Comparing the mean under breastfeeding with the mean under bottle-feeding addresses the study’s stated question about intake by feeding mode. In a within-subject design, observations from the same dyad under both modes may be related; an analysis that accounts for this relationship can be more appropriate than treating all observations as independent. General statistical guidance does not establish which method this study used.

The registry identifies standard error as the dispersion measure for the endpoint. Standard error describes the precision of an estimated mean, rather than the spread of individual intake measurements. The record does not provide the mean intake values or their standard errors, so the observed intake levels and the precision of their estimates cannot be assessed from the registry record.

The measure captures intake during the observed feeding as defined by the study. It does not, by itself, describe other aspects of feeding quality or outcomes over time. The registry’s stated objective includes feeding interactions, but numerical results for those outcomes are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry classifies the primary outcome as continuous and specifies a mean with standard error as the summary. These choices describe the form in which an outcome could be analyzed, but they are not a full statistical analysis plan. The record does not identify the particular test or model used, how the within-subject observations were handled, or the exact population contributing to the analysis. Numerical results for the primary endpoint are not reported in the registry record.

What does a mean describe?

In general, a mean is an average of observed values. For infant intake, it would describe average intake in mL for the observations included in the relevant feeding-mode group or condition. A contrast between means can describe how those average amounts differ. Because this study observes dyads during both feeding modes, interpretation depends on whether the analysis compares paired observations from the same dyad or treats observations as independent. The registry does not report which approach was used.

What does standard error describe?

In general, standard error describes the sampling uncertainty of an estimated statistic, such as a mean. It is not the same as the spread of individual measurements: individual intake can vary considerably even when the mean is estimated precisely, or measurements can be tightly grouped while the mean remains uncertain. A confidence interval commonly uses an estimate and its standard error, together with a statistical method, to represent uncertainty. The registry names standard error as the dispersion measure but gives no endpoint values or confidence interval.

Why does the within-subject structure matter?

General statistical guidance distinguishes paired from independent observations. When the same dyad is observed under both conditions, the two measurements may share characteristics and therefore be correlated. A paired analysis uses the within-dyad relationship; an independent-groups analysis does not. Accounting for pairing can affect the estimated uncertainty of a contrast. The registry describes both feeding modes for the dyads but does not state whether the analysis used a paired method, how repeated observations were represented, or how any incomplete pairs were handled.

Visit sequence is another consideration. One arm description places breastfeeding first and bottle-feeding second; the other reverses that order. In general, an order effect means that the observed outcome may depend partly on sequence or visit conditions, rather than feeding mode alone. The registry does not report whether order was randomized, adjusted for, or evaluated in the analysis. It explicitly states that allocation is not stated and that the arms are not a like-for-like control comparison.

What do the planning assumptions mean?

The registry’s sample-size description characterizes its calculation as a planning illustration based on the observed effect, not the trial’s own design. It specifies a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; it also describes planning for a stated fraction of the observed effect. Such calculations estimate the number of participants per arm that a future study might require under the stated assumptions. They are planning illustrations, not observed power and not evidence that the completed study was designed to detect a particular effect. The record does not report numerical planning outputs or a sample-size justification for the trial itself.

The stated equal-allocation assumption refers to the planning calculation and should not be mistaken for evidence about how participants were assigned in the study. The registry says allocation is not stated. Furthermore, an illustration using two arms does not establish that a paired analysis was used for the within-subject observations. The record does not describe whether planning assumptions accounted for the repeated measurements.

What cannot be inferred from the posted record?

The registry lists 2 outcome measures and 2 analyses, but does not identify all outcomes or explain how analyses correspond to them. It does not report a prespecified model, covariates, a method for handling missing data, an adjustment for multiple comparisons, or the analysis population. No mean estimates, standard errors, confidence intervals, or p-values for the primary endpoint are reported. Without these details and results, the effect estimate and its statistical uncertainty cannot be reconstructed or independently checked from the registry record.

General statistical interpretation also distinguishes statistical evidence from the size and relevance of an effect. A small p-value, if reported, would not by itself show that an effect is large or important; a non-significant result would not establish equality. Here, no primary outcome test result is reported, so neither type of interpretation is available. The appropriate reading is limited to the design and measurement information actually recorded.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 2 outcome measures and 2 analyses. It identifies infant intake during the observed feeding as the primary outcome, but does not identify the other outcome measure or explain which analysis corresponds to each measure. It also does not report whether multiple outcomes or analyses were treated as confirmatory, or whether any adjustment for multiple comparisons was used. The multiplicity approach is not reported in the registry record.

In general, testing several outcomes or contrasts can increase the chance of obtaining at least one apparently unusual result by chance. Methods for addressing this include prespecifying a primary comparison or adjusting inference across a family of tests. The record’s identification of a primary endpoint helps distinguish that measure, but does not establish the full testing hierarchy or any adjustment method. With no numerical endpoint results or analysis descriptions, the implications of multiplicity cannot be assessed.

Missing-data methods are also not reported in the registry record. The record does not say whether all observed feeding visits contributed to the primary analysis, how incomplete visits or missing weighings were treated, or whether exclusions occurred. It does not describe an intention-to-treat or per-protocol analysis population. These details matter because the analyzed observations may differ from the enrolled population, and missingness can affect estimates if it is related to feeding mode or intake.

The record describes a within-subject design but does not state how an observation from a dyad with data for only one feeding mode would be handled. It also does not report whether the analysis used a paired method. Without a stated analysis population, missing-data procedure, and multiplicity plan, the reported estimates and their uncertainty cannot be evaluated; moreover, numerical primary-outcome estimates are not reported in the registry record.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The adverse-event record lists separate mother and infant groups for the breastfeeding and bottle-feeding conditions. For each listed group, 47 are recorded as at risk, with 0 serious adverse events, 0 other adverse events, and 0 deaths. These are the counts recorded in the registry for the displayed condition groups.

A zero count means that no event of that category was recorded for the corresponding group in this registry entry. It does not establish that the underlying risk is zero, nor does it show how events were solicited, defined, or assessed. The record does not provide further details about the adverse-event collection methods, reporting windows, or whether events were assessed as related to feeding mode.

The safety counts should be read separately from the primary intake endpoint. They do not indicate whether intake differed between feeding modes, and they do not replace a comparison of outcome estimates. The registry record also does not report numerical results for the primary endpoint, so the event counts cannot be considered alongside an estimated intake effect or its uncertainty.

Because the study describes both feeding conditions for dyads and the adverse-event groups are organized by condition and by mothers or infants, the group entries should not be combined into a total. The registry reports the risk counts and event counts within each listed group; it does not provide a separate analysis of comparative safety.

12. What the Result Does, and Does Not, Mean

The study addresses a specific measurement question: whether infant intake during an observed feeding differs between breastfeeding and bottle-feeding expressed breast milk. The registry describes observing the same mother-infant dyads under both modes, with visit order varying across the arm descriptions. This makes the study relevant to understanding how feeding mode is evaluated in an observed interaction, but the record does not provide numerical results for the primary endpoint.

Without reported mean intake values, an estimated contrast, or a measure of uncertainty, the registry cannot establish the direction or size of an observed difference. It also cannot show how precise an estimate might be, whether an analysis found evidence against a null hypothesis, or whether any difference would be practically meaningful. These are distinct questions: a point estimate addresses magnitude, uncertainty describes the range compatible with the data and assumptions, and statistical significance is not by itself a measure of importance.

The design description does not support treating the arm labels as randomized treatment and control groups. The registry says allocation is not stated and explicitly cautions that the arms are not a like-for-like control comparison. The order of visits differs, and the record does not explain whether order was randomized or accounted for analytically. This limits what can be attributed to feeding mode from the available information.

The measure is also bounded by its scope: it concerns intake during the observed feeding, as measured by pre- and post-weighing, within the stated 2-hour period. It does not alone establish broader feeding quality, longer-term outcomes, or outcomes beyond those recorded in the study. Although the stated objective refers to the quality and outcome of feeding interactions, the registry does not report numerical findings for the primary measure or identify all results.

The appropriate conclusion is therefore about the record, not a treatment effect: the study was registered as completed and its design and measurement approach are described, but the registry record does not report the primary outcome results needed to quantify or interpret a feeding-mode contrast.

13. Why This Trial Matters Statistically

This study illustrates why a clear description of the comparison structure is essential in clinical and behavioral research. The registry describes observations of the same dyads under breastfeeding and bottle-feeding, while also distinguishing the order in which those observations occurred. A statistical analysis should make clear whether repeated observations are treated as paired and whether sequence is addressed. The registry does not report those analytic details, so the design description cannot be used to infer the method of analysis.

It also highlights the difference between enrollment information and an analyzed sample. The record lists enrollment of 94, but does not report the analysis population or the number of observations contributing to the primary endpoint. In a repeated-measures study, completeness across conditions can be important for a paired contrast. Reporting which observations were analyzed and how incomplete data were handled allows readers to assess the basis of the estimate.

Outcome definition and uncertainty reporting are equally important. The registry specifies mean infant intake in mL, a 2-hour timeframe, and standard error as the dispersion measure. Those details clarify what the endpoint is intended to represent, but numerical estimates and uncertainty are needed to interpret the findings. The registry record does not report these primary outcome results.

Finally, the record distinguishes a planning illustration from the trial’s design. Planning assumptions can inform future studies, but they do not substitute for a reported analysis or show that a completed study had adequate power. Read together, these features make the study a useful example of the importance of transparent reporting: design, analysis, missing data, uncertainty, and outcome estimates each answer different questions.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The principal limitation for interpreting this registry entry is that numerical results for infant intake are not reported in the registry record. The mean values, estimated contrast, standard errors, confidence interval, and p-value are not available. Without them, the direction, magnitude, and precision of the primary outcome cannot be assessed.

The record gives a within-subject study description and two visit sequences, but does not report how sequence was assigned or handled in analysis. Allocation is not stated, and the registry cautions that the arms are not a like-for-like control comparison. It is therefore not possible to assess whether order or other visit-related factors were separated from feeding mode.

Statistical methods are incompletely described. Although the endpoint is summarized as a mean with standard error and the record lists 2 analyses, it does not identify the tests or models, whether the paired structure was used, or which observations were included. The analysis population and missing-data procedures are not reported. These omissions limit evaluation of the validity and reproducibility of any comparison.

The registry lists 2 outcome measures but does not identify the other measure, describe a multiplicity strategy, or provide a complete analysis plan. It also does not provide detailed population characteristics or further eligibility information. The adverse-event entry reports zero recorded events in the listed groups, but does not describe event ascertainment or relatedness assessment.

These limitations concern what can be learned from the registry record; they do not establish that the study failed to collect or analyze information. They mean that the posted record does not contain the details required for a quantitative assessment of the primary feeding-mode comparison.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Breast Versus Bottle Study — NCT03704051.
• Registry record last updated 2024-02-28; status last verified 2024-02.
• Results first posted 2022-11-15.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

NCT03704051 is the completed Breast Versus Bottle Study, sponsored by California Polytechnic State University-San Luis Obispo. The registry lists enrollment of 94, a start date of 2018-10-15, and a primary completion date of 2020-03-15.

The study describes within-subject observations of mother-infant dyads during breastfeeding and bottle-feeding expressed breast milk, with the order of feeding visits differing between arm descriptions. The primary endpoint is mean infant intake in mL during a 2-hour period, assessed by pre- and post-weighing the baby. The record states that allocation is not stated and that the arms are not a like-for-like control comparison.

Numerical results for the primary endpoint, analysis methods, analysis population, and missing-data procedures are not reported in the registry record. The adverse-event entries list zero serious events, other events, and deaths in each recorded mother and infant condition group.