A Prenatal Bonding Intervention for Pregnant Women With Depression: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Prenatal Bonding Intervention for Pregnant Women With Depression (NCT05628675), a na na study. The primary outcome is Change on Maternal Antenatal Attachment Scale (MAAS).

2. Clinical Question

This is a feasibility study question, not a randomized test of comparative effectiveness. Without a separate comparison group, changes over time cannot be contrasted with changes among similar participants who did not receive the group. The study can be described in terms of its intended outcomes, design, recorded completion, and reported safety counts. The registry record does not report numerical findings for the MAAS or the secondary outcomes, nor does it report results for acceptability or feasibility. Consequently, the clinical question remains focused on what the study set out to evaluate; the posted information does not establish the size or direction of any change.

3. Trial Design

The registry lists this study as completed, with a single-group model and no masking. Allocation is listed as not applicable. Enrollment was 21. The study began on 2022-11-17, and primary completion was recorded as 2023-07-12. The registry identifies King's College London as the sponsor and lists the phase as not applicable.

Participants were offered Baby CHAT, a single-session, 90-minute psychoeducational group delivered antenatally. The brief description says participants would attend the group and complete questionnaires before and after it, and again 1 month later. The primary outcome was change on the MAAS, with measurements at baseline, up to 48 hours post-intervention, and 1-month follow-up. The listed secondary outcomes were change on the Prenatal Parental Reflective Functioning Questionnaire and change on the Edinburgh Postnatal Depression Scale.

A single-group design can describe observed outcomes over time among participants in the study, but it does not provide a concurrent control condition for separating intervention-associated changes from other changes over time. No randomized comparison is reported. The registry record does not report the statistical analysis plan, the method used to handle repeated measurements, or a sample-size justification for the feasibility study. It also does not report numerical results for the primary or secondary outcomes. Four participants had delivered their babies by the third MAAS timepoint and therefore did not complete the MAAS at that timepoint; the record does not give further details about other missing measurements or analysis populations.

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:

Analysis population for the primary outcome, as defined in the registry: N=4 delivered their babies by Time 3 and therefore did not complete the MAAS at this timepoint.

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 Change on Maternal Antenatal Attachment Scale (MAAS), measured over Baseline, up to 48-hours post-intervention, 1-month follow-up.

The primary endpoint is change on the Maternal Antenatal Attachment Scale (MAAS), a self-report questionnaire intended to assess maternal-fetal attachment during pregnancy. The description identifies 19 items, each on a 5-point Likert scale, covering attitudes, feelings, and behaviors toward the fetus. The total score ranges from 19 to 95, with higher scores indicating stronger prenatal bonding and described as a better outcome.

Using a defined measure at multiple timepoints allows researchers to describe participants’ reported attachment before and after the group and at follow-up. The stated timepoints are baseline, up to 48 hours post-intervention, and 1-month follow-up. This design can capture change within the observed group, but without a separate comparison group it cannot establish how much of any change is attributable to the intervention rather than other influences.

The registry record reports that four participants had delivered their babies by Time 3 and therefore did not complete the MAAS at that timepoint. It does not report the MAAS scores, changes, variability, or an estimate of uncertainty. Thus, the endpoint’s measurement properties and intended interpretation are described, but the actual outcome pattern is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods describe how measurements are summarized, compared, and interpreted. The registry record identifies the primary measure as a continuous score and describes its summary parameter as a mean with standard deviation. It does not report the actual mean scores, standard deviations, changes, confidence intervals, or statistical tests for the primary outcome. The specific analysis methods used for the posted outcomes are not reported in the registry record.

What does a mean and standard deviation describe?

In general, a mean describes the average score in a group, while a standard deviation describes how spread out individual scores are around that average. These summaries answer different questions: the mean gives a central value, and the standard deviation gives information about participant-to-participant variability. Neither one alone shows how precisely a group mean or an estimated change has been measured. The record identifies mean and standard deviation as the summary approach for the primary measure, but does not include their numerical values.

What would change over time mean in a single-group study?

In general, measuring participants at several timepoints can describe how scores in the observed group vary over time. A change from baseline is a within-group description, not a comparison against what would have happened without the intervention. A control group can help assess differences between intervention and comparator groups, but this study is listed as single-group and has no like-for-like control comparison. The registry record does not report the method used to analyze the repeated MAAS measurements or how the different timepoints were handled statistically.

How should uncertainty be understood?

In general, a confidence interval gives a range of values compatible with an estimate under the assumptions of the statistical method. Its width conveys precision: wider intervals indicate greater uncertainty, while narrower intervals indicate greater precision. A confidence interval does not resolve limitations in design, such as the absence of a comparison group. The registry record does not report confidence intervals for the outcome estimates, so their precision cannot be evaluated from the posted information.

What do the planning assumptions represent?

In general, sample-size planning asks how many participants might be needed under specified assumptions about the effect to detect, the significance level, allocation, and statistical model. The registry record describes a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two hypothetical arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. These are planning assumptions, not evidence that the actual single-group study used two arms or that a particular number of participants was required by its protocol. The record does not report the study’s own sample-size justification. Planning estimates are not observed power and do not describe the probability that the intervention is effective.

Why does over-dispersion matter in general?

For count outcomes, over-dispersion means that observed variability is greater than a statistical model expects. If a model assumes less variability than the data contain, estimates of uncertainty may be too small. This is a general consideration for count data; the primary outcome in this study is a continuous MAAS score, and the registry record does not report that an over-dispersion model was used. No count-outcome analysis method is reported.

What can be concluded from the posted methods information?

The record identifies the measure, scale direction, timepoints, and planned summary type. It also lists three outcome measures and six analyses. Those details do not reveal how analyses were conducted, whether estimates were adjusted, or how repeated measurements and missing data were handled. Those methods are not reported in the registry record. Without numerical estimates and uncertainty measures, readers cannot assess the magnitude or precision of outcome changes. The single-group design also means that even a reported within-group change would not by itself establish a causal effect.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists three outcome measures and six analyses. It does not report whether the analyses were organized under a prespecified hierarchy, whether one outcome was treated as confirmatory, or whether any adjustment for multiple testing was used. When several outcomes or analyses are examined, the chance of seeing an apparently notable finding by chance can increase. In general, prespecified analysis plans and appropriate handling of multiplicity help readers understand how to interpret multiple results. The details of such a plan are not reported in the registry record.

The primary outcome was scheduled at baseline, up to 48 hours post-intervention, and 1-month follow-up. The record specifically states that four participants had delivered their babies by Time 3 and therefore did not complete the MAAS at that timepoint. It does not state how the missing Time 3 scores were handled in analysis, whether participants were included in analyses at earlier timepoints, or whether other measurements were missing.

The analysis population is not reported in the registry record. Nor are the methods used to address missing data, the number of participants contributing outcome measurements at each timepoint, or any sensitivity analyses. In general, missing-data methods rely on assumptions about why measurements are unavailable; different assumptions can lead to different interpretations. The recorded reason for the four missing Time 3 MAAS measurements is delivery before that assessment, but the record does not describe the statistical handling of those observations. As a result, the completeness and robustness of the outcome analyses cannot be evaluated from 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 intervention group safety record lists 20 participants at risk for serious adverse events and zero affected, with no serious adverse event terms listed. It also lists 20 participants at risk for other adverse events and zero affected. Deaths are recorded as zero. These figures are the counts reported by the registry, not estimates of risk beyond the participants and reporting represented in that record.

The enrollment count is 21, while the safety counts use 20 participants at risk. The registry record does not explain this difference, so no reason for it should be inferred. It also does not provide definitions of the adverse-event categories, details about how events were collected, or additional event descriptions. Zero recorded events therefore means that the registry reports none in these categories for the stated at-risk group; it does not establish that no event occurred outside the recorded information or that an intervention has no possible risks.

Safety counts are separate from the primary outcome. They do not indicate whether MAAS scores changed, whether the group was acceptable, or whether it was feasible to deliver. The record does not report a comparator safety group, and the single-group design does not allow a relative safety comparison.

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

The registry record establishes that a completed, single-group study evaluated a 90-minute antenatal psychoeducational group called Baby CHAT among pregnant women with depression. It identifies the primary measure as change on the MAAS and lists measures of parental reflective functioning and depression as secondary outcomes. It also records enrollment of 21 and notes that four participants did not complete the MAAS at the 1-month follow-up because they had delivered their babies by that timepoint.

The record does not report numerical results for the primary or secondary outcomes. It therefore does not show whether scores increased, decreased, or stayed similar, nor how precisely any estimated change was measured. It also does not report findings about acceptability or feasibility. Completion status should not be treated as a result demonstrating that the intervention was acceptable or feasible.

Even if within-group changes were available, the single-group design would limit causal interpretation. There is no separate control group to indicate how measurements might have changed without Baby CHAT. The record does not report a randomized comparison or an analysis that could isolate an intervention effect from other influences over time.

The safety record lists zero serious and zero other adverse events among 20 participants at risk, with zero deaths. These figures describe the events recorded in the registry and do not establish that no unrecorded events occurred or that there is no risk. Taken together, the registry information describes the study’s purpose, design, measures, follow-up issue, and recorded safety counts. It does not establish that Baby CHAT changes bonding, parental reflective functioning, or mood, and it does not provide an estimate of the size or precision of any such change.

13. Why This Trial Matters Statistically

Feasibility studies can address practical questions that precede a larger evaluation: whether an intervention can be delivered to the intended population, whether participants engage with it, and whether outcome measures can be collected over time. This study was designed around those questions as well as the potential for changes in bonding, parental reflective functioning, and mood. Keeping these aims distinct from a comparative effectiveness claim is important when interpreting a single-group study.

The registry identifies a specific primary measure, the MAAS, and scheduled assessments at baseline, up to 48 hours after the group, and 1-month follow-up. It also documents a follow-up constraint: four participants had delivered their babies by the third assessment and did not complete the MAAS then. That information matters statistically because outcome availability can differ across timepoints, and readers need to know how missing measurements were handled to judge the resulting estimates.

The record also illustrates why design and reporting details matter alongside outcome measures. A single-group design can describe participants’ scores, but it cannot supply a concurrent control comparison. The registry record does not report numerical outcome findings, analysis methods, or missing-data handling, so the evidence available does not support an assessment of the magnitude or precision of changes.

Finally, the recorded adverse-event counts are useful descriptive information but are not a substitute for outcome results or a comparative safety analysis. The value of this record is therefore primarily in clarifying the intended feasibility and outcome questions and in identifying what information remains unavailable for statistical interpretation.

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 most consequential limitation for interpreting outcomes from the registry record is the absence of numerical results. It does not report MAAS scores or changes, summary statistics, estimates of uncertainty, or numerical findings for the secondary outcomes. It also does not report results addressing acceptability or feasibility. As a result, the magnitude, direction, and precision of any outcome change cannot be assessed from the posted information.

The study is listed as single-group, with no like-for-like control comparison. This design can describe outcomes in participants who received the group, but it cannot distinguish intervention-associated changes from other changes over time. The record does not report randomization, a comparator arm, or a comparative analysis.

Follow-up completeness is another specific concern. Four participants had delivered their babies by Time 3 and therefore did not complete the MAAS at that timepoint. The registry record does not report the number contributing data at other timepoints, how missing scores were handled, or whether additional measurements were missing. It also does not report the analysis population or sensitivity analyses.

The record lists three outcome measures and six analyses, but does not report an analysis hierarchy, multiplicity adjustment, or the statistical methods used. A sample-size justification for the study is not reported in the registry record. Finally, safety counts are limited to the reported categories and at-risk group; the record does not provide event definitions or explain why the safety denominator is 20 while enrollment is 21.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: A Prenatal Bonding Intervention for Pregnant Women With Depression — NCT05628675.
• Registry record last updated 2025-06-25; status last verified 2022-08.
• Results first posted 2025-06-25.
• 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

This completed study examined Baby CHAT, a single-session, 90-minute antenatal psychoeducational group for pregnant women with depression. It used a single-group design with no masking and enrolled 21 participants. The primary outcome was change on the MAAS at baseline, up to 48 hours post-intervention, and 1-month follow-up. Secondary outcomes were change on the Prenatal Parental Reflective Functioning Questionnaire and the Edinburgh Postnatal Depression Scale.

The registry record reports that four participants had delivered their babies by the third MAAS timepoint and did not complete that assessment. It does not report numerical outcome results, the statistical analysis methods, or how missing measurements were handled. Safety counts list zero serious adverse events, zero other adverse events, and zero deaths among 20 participants at risk. With no separate control group and no numerical outcome findings reported, the record does not permit an assessment of the size or precision of outcome changes.