Feeding My Baby - A National WIC Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Feeding My Baby - A National WIC Study (NCT02031978), a registered phase not stated study. The primary outcome is Breastfeeding Initiation.

2. Clinical Question

The broad research question is how infant and toddler feeding practices occur among families receiving WIC services, and how those practices relate to nutrition-related issues during early childhood. The registry summary names breastfeeding practices and support, general feeding practices, nutritional intake, transitions in feeding, early precursors of obesity, and family factors as areas of interest. It also describes interest in characteristics of WIC in selected sites and how those relate to feeding decisions and practices.

The primary endpoint narrows that broad scope to breastfeeding initiation. It captures whether initiation occurred, not the duration or exclusivity of breastfeeding, the amount of support received, or the reasons for a feeding decision. The registry record does not report a comparison group or an analysis connecting initiation to later outcomes. The question is therefore descriptive in the record as posted: it identifies what the study intended to assess, without establishing a between-group effect or a relationship with later health outcomes.

3. Trial Design

The record describes the Women, Infant, and Children (WIC) Infant-Toddler Feeding Practices Study - II as a cohort study of families receiving WIC services. Its enrollment is listed as 4367. The recruiting description focuses on pregnant women enrolling in WIC for the first time for that pregnancy and mothers or caregivers of infants younger than 2.5 months of age enrolling in WIC for the first time. The record does not specify how many participants contributed data to the primary endpoint.

The study is not presented as a randomized comparison. Allocation is not stated, and the record cautions that arms are not a like-for-like control comparison. No assigned treatment or control condition is described. The study's stated purpose is to examine feeding practices and related nutrition issues in the WIC population, rather than to estimate the effect of a randomized intervention.

The start is listed as 2013-07 and primary completion as 2023-07. An update dated November 25, 2020, says the study would follow participants through child age 9 years. The registry status is UNKNOWN. These record details describe the planned scope and timing, but do not establish that every participant completed follow-up or that all planned data were collected.

The primary outcome measure is breastfeeding initiation, defined as whether the mother initiated breastfeeding after the child was born, with a timeframe of the first month after birth. The registry record lists one outcome measure and 0 analyses. It does not report a statistical analysis plan, a completed analysis population, or a comparison of results between groups. The sponsor is the USDA Food and Nutrition Service.

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.

Overall Study

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: The Main Analysis sample includes 3,777 cases that have completed a 1- and/or 3-month interview.

6. Primary Endpoint

The registry lists the primary outcome as Breastfeeding Initiation, measured over first month after birth of child.

The primary endpoint records whether the mother initiated breastfeeding after the child was born. Its stated timeframe is the first month after birth of the child, and the unit is participants. The registry describes the measure as a count of participants and classifies its outcome type as binary: a participant either meets the definition of initiation or does not. No operational detail beyond that description is reported in the registry record.

This endpoint is used to describe one specific early feeding practice. A binary initiation measure can provide a straightforward count of participants meeting the endpoint, but the count alone does not indicate the proportion of all eligible participants unless the relevant denominator is also known. The registry record does not report endpoint counts, denominators, or a result estimate.

Initiation is narrower than the study's broader interests in breastfeeding support, general feeding practices, nutritional intake, feeding transitions, early precursors of obesity, and family factors. It does not by itself describe how long breastfeeding continued, whether it was exclusive, or what support families received. Nor does the endpoint establish a link between breastfeeding initiation and later nutrition or health outcomes. Those questions would require additional measures and analyses, which are not reported for this endpoint in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the endpoint type mean?

The primary outcome is classified as binary and expressed as a count of participants. In general, a binary endpoint assigns each participant to one of two outcome states according to a defined criterion. Here, the criterion is whether the mother initiated breastfeeding after the child was born during the first month after birth. A count describes how many participants meet that criterion; interpreting the count as a frequency also requires knowing how many participants were assessed and had usable data. Neither the endpoint count nor its denominator is reported in the registry record.

A count is not itself a measure of uncertainty or a comparison. To estimate a proportion, an analysis needs a denominator. To compare groups, it needs clearly defined groups and a suitable contrast. The record does not report those details for breastfeeding initiation, and it cautions that the study is not a randomized comparison with like-for-like arms.

What analysis is reported?

The registry record lists 0 analyses. It does not report an estimated effect, an uncertainty interval, a hypothesis test, or a model for the primary outcome. It also does not report whether the intended analysis would be unadjusted or adjusted, which covariates might be included, or how any site-level differences would be represented. These omissions mean no particular inferential method can be attributed to the study based on this record.

In general, an analysis of a binary outcome may estimate a count, a proportion, or a contrast between proportions, depending on the research question and the available comparison groups. A model may be used to adjust for prespecified participant or site characteristics, but that choice requires a stated analysis plan and appropriate data. The registry record does not state that such a model was used. It would therefore be inappropriate to infer an adjusted result, a causal effect, or a statistical significance finding.

How should planning illustrations be read?

The record describes planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. These are assumptions for illustrative sample-size calculations, not a report of the study's own design or an observed result. The registry record does not report the underlying observed effect or the values needed to evaluate a particular illustration.

In general, a sample-size calculation asks how much information would be needed to detect an effect under specified assumptions. Its output is conditional on the assumed effect, significance level, allocation, and statistical approximation. When an assumed effect is based on an observed estimate, uncertainty in that estimate also matters. An illustration does not show that a study had a particular probability of detecting an effect after data collection, and it is not observed power. In this case, the stated equal-allocation assumption should not be mistaken for evidence that the cohort was actually divided into comparable randomized groups; the record explicitly says otherwise.

For binary outcomes, the event rate and the comparison being planned can affect the sample size required. The registry record does not report the event rate for breastfeeding initiation, a primary comparison, or a design-based sample-size justification. The planning assumptions therefore should not be treated as confirmation that the enrolled cohort was sized for a specified primary analysis.

Why does the study design matter?

Randomization, when used, can balance measured and unmeasured characteristics between assigned groups on average. This record does not describe randomized allocation. Instead, it describes a cohort of WIC participants and says that arms are not a like-for-like control comparison. General statistical interpretation therefore needs to distinguish a descriptive result from a treatment-effect estimate. A difference between groups, if one were reported, could reflect differences in who entered each group as well as the exposure or characteristic being compared.

The study summary also names selected WIC site characteristics and family factors as areas of interest. In general, data collected within sites or families can have related observations, and analyses may need to account for such structure when estimating uncertainty. The record does not report whether this was planned or performed, so no clustering adjustment or other specific method should be assumed.

Overall, the methods information in the registry record supports a description of the intended endpoint and some planning assumptions, but not a reconstruction of the primary analysis. The observed endpoint data, analysis population, model, adjustment strategy, and inferential results are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists one outcome measure, with breastfeeding initiation identified as the primary endpoint. It does not report a multiplicity plan, such as whether any additional outcomes were designated as secondary or exploratory for formal hypothesis testing, or how error rates would be controlled across tests. The study summary names several research interests, including feeding practices, nutritional intake, feeding transitions, early precursors of obesity, and family factors. These stated interests do not establish how many outcomes were analyzed or whether any formal testing took place.

The record lists 0 analyses, so it does not provide a set of results across which multiplicity could be assessed. No p-values or estimates are reported for the endpoint. Without an analysis plan, it is also not possible to determine whether the primary outcome was tested once, whether alternative definitions were considered, or whether reporting decisions were prespecified.

Missing-data procedures are not reported in the registry record. It does not state how absent breastfeeding information, incomplete follow-up, or participants without endpoint data were handled. The analysis population is also not described. Although enrollment is listed as 4367, the record does not say how many participants were assessed for this endpoint or how any exclusions were determined.

In general, missing observations can affect both the estimated outcome frequency and its uncertainty, particularly if the likelihood of missingness is related to participants' circumstances or outcomes. The appropriate handling depends on the study data and assumptions. No particular missing-data method, imputation approach, or sensitivity analysis can be attributed to this study from the registry record. As a result, neither the impact of missing data nor the robustness of a result can be evaluated.

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

The registry record establishes that breastfeeding initiation was the primary endpoint of a study of infant and toddler feeding practices among families receiving WIC services. It defines the endpoint as whether the mother initiated breastfeeding after the child was born, during the first month after birth. It does not report the endpoint result, its denominator, or an analysis. The record therefore does not show how common initiation was in the study cohort or how precisely it was measured.

The study's broader stated aims include examining feeding practices, nutrition, early precursors of obesity, family factors, and WIC site characteristics. A stated research aim is not evidence of an observed relationship. The registry record does not establish whether breastfeeding initiation was associated with later nutrition or health outcomes, or whether any observed patterns were caused by WIC participation or other factors.

The design description also limits causal interpretation. The record says the study is not a randomized comparison, allocation is not stated, and arms are not like-for-like controls. A cohort can be useful for describing experiences and examining associations, but group differences may reflect characteristics that differ across groups. The posted record does not report an adjustment strategy that could address such differences.

The enrollment listed as 4367 describes the record's enrollment figure; it should not be read as the endpoint denominator or as the number with complete data. The record does not report how many participants contributed to the outcome or how missing information was handled. The status is UNKNOWN, so the status entry does not resolve whether collection or follow-up was completed as planned.

In general, a registry description records intentions and specified study features; it is not a substitute for an analysis report. For this study, the record identifies what was to be measured and the population of interest, but does not support conclusions about the outcome's frequency, precision, statistical significance, or causal meaning.

12. Why This Trial Matters Statistically

This study is statistically interesting because it combines a clearly described binary primary endpoint with a broad research agenda about early feeding and nutrition in a WIC population. Breastfeeding initiation is a focused measure, while the summary also describes interest in feeding transitions, nutritional intake, family factors, early precursors of obesity, and characteristics of selected WIC sites. Keeping these distinct matters: a single endpoint cannot stand in for all the study's broader questions.

The registry record also makes a design distinction that is essential to interpretation. It describes a cohort, not a randomized comparison, and explicitly cautions that arms are not like-for-like controls. That statement prevents an analyst from treating any group contrast as a randomized treatment effect. Descriptive estimates and associations can be informative, but their meaning depends on who was observed, how groups were formed, and how differences were addressed.

For a binary outcome, the event count needs a relevant denominator to express how frequent the outcome was, and an estimate needs uncertainty information to show its precision. The registry record reports neither the endpoint count nor the denominator, and it lists 0 analyses. This makes the gap between study purpose and reported results particularly important: the primary question is specified, but its answer is not present in the record.

The planning assumptions also illustrate why design assumptions must be separated from study findings. A normal-approximation sample-size illustration using a two-sided significance level of 0.05 and equal allocation between two arms is not evidence that the cohort had that allocation, nor does it report observed power. Recognizing that distinction avoids reading planning calculations as outcomes.

Overall, the record is useful for identifying the population, endpoint, and limits of the stated design. Its statistical contribution as posted is descriptive of study intent rather than evidence about the endpoint's observed frequency or its relationship to later outcomes.

13. 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 main limitation for interpreting the primary endpoint is that the registry record does not report any outcome result or analysis. It gives no count of participants who initiated breastfeeding, denominator, effect estimate, confidence interval, or p-value. The record therefore does not allow assessment of the endpoint's magnitude or precision.

The enrollment figure of 4367 is not identified as the number included in an endpoint analysis. The registry does not report how many people had endpoint data, whether follow-up was complete, which analysis population was used, or how missing observations were addressed. The status is UNKNOWN, and the record does not explain whether this reflects the study's conduct or reporting status.

The recruitment description is specific to pregnant women entering WIC for the first time for that pregnancy and mothers or caregivers of young infants entering WIC for the first time. Results from such a recruitment frame, if reported, would not automatically apply to families outside that frame. The registry does not provide details on participant characteristics, recruitment by site, or representativeness of the enrolled cohort.

The nonrandomized design is another limitation for causal questions. Allocation is not stated, and the record says arms are not a like-for-like comparison. It does not report a comparison group, adjustment strategy, or method for accounting for site and family characteristics. As a result, the record cannot establish causal effects or rule out confounding in any potential group comparison.

Finally, the endpoint is limited to initiation during the first month after birth. It does not capture duration, exclusivity, quality of support, or reasons for feeding decisions. Those details and any analysis linking initiation to later outcomes are not reported in the registry record.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Feeding My Baby - A National WIC Study — NCT02031978.
• Registry record last updated 2022-06-09; status last verified 2022-05.
• Results first posted 2021-06-10.
• 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.

17. Record Summary

Feeding My Baby - A National WIC Study is listed under the official title Women, Infant, and Children (WIC) Infant-Toddler Feeding Practices Study - II (ITFPS-2). The sponsor is the USDA Food and Nutrition Service. The registry lists enrollment as 4367, a start of 2013-07, primary completion of 2023-07, and status UNKNOWN.

The record describes a cohort of WIC participants and identifies breastfeeding initiation during the first month after birth as the primary endpoint. It states that the study is not a randomized comparison, allocation is not stated, and arms are not like-for-like controls. An update dated November 25, 2020, says participants would be followed through child age 9 years.

The record lists one outcome measure and 0 analyses. It does not report an observed primary-endpoint result, analysis population, or statistical analysis plan. The registry information therefore describes study scope and measurement, but does not provide evidence about the outcome's frequency, precision, or relationship to later outcomes.