A Home Exercise Program for Women With Infants & Young Children: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Home Exercise Program for Women With Infants & Young Children (NCT01738984), a randomized phase 3 study. The primary outcome is Minutes Per Week of Moderate-to-Vigorous Physical Activity (MPVA Min/wk) Assessed at 12 Weeks.

2. Clinical Question

3. Trial Design

The registry describes a completed, randomized, double-masked, parallel-group trial, listed as Phase 3 and sponsored by the University of Hawaii. Enrollment is listed as 499. The registry dates the start to 2012-12 and primary completion to 2014-12. Those dates describe the trial record; they do not establish how long each participant was followed beyond the reported outcome timeframes.

The two behavioral interventions were the MomZing Web Program and a standard exercise DVD. The record describes MomZing as an online program with a menu of short exercise videos and describes the DVD as offering exercise demonstrations. The primary outcome was assessed at 12 weeks, as was the posted secondary outcome concerning return to smoking. The record does not report how participants were allocated between groups, how masking was implemented for these behavioral interventions, or whether anyone assessing the outcomes was masked.

The record contains an internal phase discrepancy: the trial-design information lists Phase 3, while the brief summary calls the project a Phase II STTR project. These descriptions are not reconciled in the registry record. The protocol, randomization procedure, planned sample-size justification, and statistical analysis plan are not reported in the registry record. The record also lists three outcome measures but provides one posted secondary outcome and no reported analyses.

The primary outcome denominators are 186 for MomZing and 210 for the DVD group. These are smaller than the listed enrollment, but the registry record does not report participant flow, reasons for non-inclusion, or the analysis population used to produce the endpoint summaries. The adverse-event denominators are reported separately and should not be assumed to describe the primary-outcome analysis population.

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

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.

6. Primary Endpoint

The registry lists the primary outcome as Minutes Per Week of Moderate-to-Vigorous Physical Activity (MPVA Min/wk) Assessed at 12 Weeks, measured over 12 weeks.

The primary endpoint is minutes per week of moderate-to-vigorous physical activity (MVPA) assessed at 12 weeks. The registry says physical activity was obtained through online surveys at that assessment point. The reported quantity is a group mean, with a 95% confidence interval for each intervention group.

Weekly activity minutes are relevant to the program’s stated goal of increasing home-based physical activity among new mothers. A mean gives a summary of the group’s reported activity level, but it does not describe how activity is distributed among individual participants. Two groups can have similar means while differing in the spread or shape of individual responses; those details are not posted for this endpoint.

The survey-based measure reflects reported activity, rather than a measurement method described as direct or device-based in the record. The registry record does not report the survey instrument, its scoring details, how missing answers were handled, or whether the measure was validated for this setting. The 12-week timing provides a defined assessment point, but the posted primary result alone does not show whether any change was sustained beyond that point. Nor does a group mean by itself establish a causal contrast: interpretation of a difference between groups depends on a direct analysis and its uncertainty, which are not reported for the primary endpoint.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is continuous: it is measured in minutes per week and summarized as a mean in each group. A mean is the arithmetic average of the observed values in the relevant analysis group. The registry reports 95% confidence intervals alongside these means. A confidence interval describes statistical uncertainty around an estimate under the assumptions of the method used; it is not a range containing 95% of individual participants’ activity levels, and it does not mean there is a 95% probability that a fixed population value lies in the particular interval.

The intervals reported for the two groups apply to their separate means. A treatment comparison normally requires an estimate of the contrast between groups, together with uncertainty for that contrast. The primary registry results do not include such a contrast or a test of the primary hypothesis. Comparing two means by eye, or treating the two separate confidence intervals as if they were an interval for a difference, would not supply the missing analysis. The registry record does not report the primary model, covariate adjustment, standard error method, or assumptions used to obtain the endpoint intervals.

General statistical explanation: In a randomized trial, a between-group analysis can estimate the difference associated with assignment to the interventions, subject to the trial’s design, outcome measurement, and analysis choices. Randomization supports comparability in expectation, but it does not guarantee that every observed group characteristic is balanced, nor does it remove the need to report the planned analysis and missing-data handling. The registry record identifies randomization but does not report its implementation details or the analysis plan.

The smoking outcome is binary: participants either were or were not counted as having returned to smoking for the reported outcome. The posted counts are 3 in each group, with denominators of 186 and 210. The unadjusted recalculation reports a risk difference of 0.002 and a 95% confidence interval from -0.022 to 0.026, with p = 0.881. A risk difference expresses the contrast between the two observed proportions on an absolute scale. The interval indicates substantial uncertainty around this small estimated contrast and includes zero, the value corresponding to no difference. The reported p-value is not evidence that the groups are identical; it describes compatibility of the observed data with a specified null comparison under the test’s assumptions.

The reported risk ratio is 1.129, with a 95% confidence interval from 0.231 to 5.526. The odds ratio is 1.131, with a 95% confidence interval from 0.226 to 5.674. These relative measures compare event frequency on different scales. Their wide intervals indicate that the event counts do not pin down the relative contrast precisely. With only 3 recorded events in each group, small changes in event counts could materially affect a relative estimate. These are unadjusted recalculations; no reported sponsor analysis is listed for this endpoint.

The registry also gives a planning illustration based on the observed smoking effect. It reports participants per arm for 80% power and for 90% power under an assumed two-sided significance level of 0.05, equal allocation, and a normal approximation. For planning for 100% of the observed effect, the figures are 69,188 participants per arm for 80% power and 92,623 for 90% power. For planning for 75% of the observed effect, they are 121,166 and 162,207 participants per arm, respectively. For planning for 50% of the observed effect, they are 268,494 and 359,436 participants per arm, respectively. These figures are planning illustrations, not observed power, and they are not the trial’s own sample-size justification. The protocol’s sample-size rationale is not reported in the registry record.

General statistical explanation: Over-dispersion occurs when variability in the data exceeds what a chosen statistical model assumes. If a model understates variability, standard errors may be too small and confidence intervals too narrow. The registry record does not report an over-dispersion assessment or enough detail to determine whether it was relevant to either endpoint. Similarly, the posted primary result does not report a variance estimate or an analysis model, so readers cannot independently assess the assumptions underlying its intervals.

For the smoking comparison, the recalculated quantities use the posted summary counts without adjustment. They should not be confused with a prespecified, covariate-adjusted, or sponsor-reported analysis. The registry lists no reported analyses for the endpoint. A prespecified plan would clarify which contrast, method, and population were intended and how multiple outcomes were to be handled; that information is not reported in the registry record. The record also does not state whether any interim analyses were planned or conducted.

10. Multiplicity, Missing Data and Analysis Populations

The registry record does not report a multiplicity strategy, such as a hierarchy for testing outcomes, a designated family of comparisons, or an adjustment to account for multiple testing. It lists three outcome measures but posts a primary result and one secondary result. Without a complete list of planned outcomes and analyses, it is not possible to determine how the posted results relate to all outcomes assessed or whether selective reporting is a concern.

The record does not report a statistical analysis plan, primary hypothesis test, interim analyses, or adjustment for baseline variables. It also does not identify an analysis population, such as all randomized participants or a subset defined by available outcome data. These omissions matter because analytic choices can affect the estimated contrast and its uncertainty. The primary endpoint is summarized by separate means and confidence intervals, without a reported between-group test or contrast.

Participant flow and missing-data handling are not reported in the registry record. The overall enrollment is 499, while the primary outcome denominators are 186 and 210. The record does not explain these counts, say how many participants lacked 12-week measurements, describe reasons for missingness, or state whether any imputation or sensitivity analysis was used. As a result, the extent and possible consequences of missing primary-outcome data cannot be assessed from the registry results.

The smoking outcome also has denominators smaller than total enrollment, and the record does not explain how participants without a recorded smoking outcome were handled. The adverse-event denominators are 250 and 249, which are reported separately from the endpoint denominators; the registry record does not clarify the relationship between these populations. This difference in denominators should not be interpreted as evidence of a particular exclusion or follow-up process.

These gaps do not establish that the analyses were inappropriate. They mean that readers cannot evaluate key features of the analysis process from the registry record alone, including missingness, multiplicity, and the alignment between planned and posted analyses.

11. Safety Results

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

Other (non-serious) adverse events

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

Most frequent non-serious adverse event terms

The registry reports 0 serious adverse events among 250 participants at risk in the MomZing group and 0 among 249 at risk in the standard exercise DVD group. It lists 3 other, non-serious adverse events in the MomZing group and 2 in the DVD group. The record does not provide serious adverse-event terms, and the death counts are not reported.

These counts describe the adverse events recorded in the registry; they do not by themselves establish that no serious events occurred outside the reported record or that the interventions have equivalent safety. Zero recorded serious events in the listed denominators still leaves uncertainty about uncommon events, and the registry record does not describe event definitions, ascertainment procedures, severity grading for other events, or follow-up duration for safety.

The safety denominators differ from those posted for the primary outcome. The registry record does not explain why, so the safety counts should be interpreted using their own listed denominators rather than assumed to represent every enrolled participant or the primary analysis population. The figures offer limited descriptive information and are not a complete safety assessment.

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

The primary result describes average self-reported MVPA at 12 weeks in each group. The MomZing group mean was 217.7 minutes per week, and the standard exercise DVD group mean was 203.2 minutes per week. Their confidence intervals convey uncertainty around the separate group means. These values do not, by themselves, establish the size or precision of a difference between interventions.

The registry record does not report a primary treatment-effect estimate or formal comparison. Consequently, the posted primary numbers cannot support a firm claim that one group had higher or lower activity than the other, nor can they establish that the groups were equivalent. A direct contrast and its confidence interval would be needed to quantify the comparative result. The record also does not report enough information about participant flow and missing data to assess how the endpoint summaries relate to all enrolled participants.

The findings are specific to the reported measure and assessment time. They do not show whether activity changed from baseline, whether any difference persisted beyond 12 weeks, or whether reported activity corresponded to objectively measured activity. The registry summary describes online surveys and does not provide detail on the instrument or its measurement properties.

The smoking outcome is a separate secondary measure with 3 recorded events in each group and an imprecise unadjusted comparison. It cannot be used to infer a relationship between physical activity and smoking, and it does not establish an effect on other health behaviors. Likewise, the adverse-event counts provide only limited descriptive information; they do not settle questions about uncommon harms.

These registry results are therefore best understood as posted endpoint summaries rather than a complete account of comparative effectiveness or safety. The trial is listed as completed, but its protocol, analysis plan, participant flow, and several analytic details are not reported in the registry record. Those omissions limit the strength and scope of conclusions that can be drawn from the posted results.

13. Why This Trial Matters Statistically

This trial is statistically instructive because it reports means and confidence intervals for the primary endpoint but no direct comparison between randomized groups. Readers can see the observed mean in each group and its within-group precision, yet the central comparative question remains unanswered by the reported primary analysis. It illustrates why separate group summaries are not a substitute for an estimated contrast with uncertainty.

It also highlights the importance of denominator context. The registry lists enrollment of 499, while the primary outcome summaries use 186 and 210 participants. Without participant flow and missing-data information, the relationship between these numbers cannot be evaluated. Clear reporting of who contributed data and how missing outcomes were handled is essential to judging the relevance of a result.

The smoking outcome shows a different statistical challenge: few recorded events and a wide interval around the comparative estimate. Such results can be compatible with several materially different underlying effects. A non-small p-value is not proof of no effect, and a point estimate alone is not precise evidence of a meaningful effect.

Finally, the record illustrates the value of a clearly documented analysis plan, including the primary comparison, secondary outcome hierarchy, multiplicity handling, and sample-size rationale. The registry provides planning illustrations based on the observed smoking effect, but explicitly these are not the trial’s own design justification. Taken together, the posted record supports careful distinction between descriptive summaries, unadjusted recalculations, and prespecified trial analyses.

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.

Several limitations specific to this record constrain interpretation. The primary endpoint is measured through online surveys, but the registry does not identify the instrument or describe its validation, scoring, or missing-response rules. The outcome is reported at 12 weeks only, so the posted result does not establish longer-term maintenance of activity despite the program’s stated goal of maintaining exercise increases over time.

The primary outcome denominators total less than the listed enrollment, and participant flow is not reported. Reasons for missing outcome data and the methods used to address it are also not reported. Without this information, it is not possible to assess whether the endpoint summaries may reflect a selected subset of enrolled participants. The record also does not report a primary between-group analysis, which prevents direct assessment of the central comparative question.

The smoking result is based on 3 events in each group and has broad uncertainty. The registry lists three outcome measures but posts only one secondary outcome, and it does not explain the status of the other measures. No multiplicity approach or analysis plan is reported. The phase description is also inconsistent: the trial-design information lists Phase 3, while the brief summary describes a Phase II STTR project.

The record describes the interventions but does not report details of randomization, allocation concealment, masking implementation, adherence, or intervention use. For behavioral interventions, these details would help readers understand exposure and potential sources of bias. The registry’s adverse-event information is similarly limited: event definitions and ascertainment are not described, and death counts are not reported. These are reporting limitations; they do not, on their own, prove that any particular bias or safety issue occurred.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: A Home Exercise Program for Women With Infants & Young Children — NCT01738984.
• Registry record last updated 2016-04-12; status last verified 2016-03.
• Results first posted 2016-04-12.
• 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

The registry describes a completed randomized, double-masked, parallel-group comparison of the MomZing Web Program with a standard exercise DVD, sponsored by the University of Hawaii. The record lists Phase 3 and enrollment of 499, with a start date of 2012-12 and primary completion in 2014-12. The brief summary instead describes the project as Phase II, and the registry record does not reconcile the difference.

The primary endpoint was mean MVPA minutes per week assessed by online survey at 12 weeks. The posted group means are 217.7 for MomZing and 203.2 for the DVD group, with separate 95% confidence intervals. No primary between-group analysis is reported. The posted secondary outcome records 3 returns to smoking in each group; its unadjusted recalculation is imprecise. Serious adverse-event counts are 0 in both groups, with listed risk denominators of 250 and 249. The analysis plan, participant flow, missing-data methods, and sample-size justification are not reported in the registry record.