Safety of 4CMenB Exposure During Pregnancy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety of 4CMenB Exposure During Pregnancy (NCT02640677), a registered phase not stated study. The primary outcome is Major Congenital Malformation (MCM).

2. Clinical Question

The registry was intended to evaluate the safety of pregnancy exposure to 4CMenB by describing health outcomes for pregnant women and their infants. It focused on women in the United States who received at least 1 dose of 4CMenB within 30 days before their last menstrual period or at any time during pregnancy. The main outcome named in the record was major congenital malformation (MCM), with a timeframe of registry enrollment. Spontaneous abortions and still births were listed as secondary outcomes.

The question is descriptive: it concerns outcomes among people with a specified exposure, rather than a contrast between randomized groups. The registry record does not report an estimate of the frequency of MCM or other pregnancy outcomes. With enrollment of 2 and no collected data for the primary outcome, the record cannot answer the intended question with an outcome estimate.

3. Trial Design

NCT02640677, titled “Safety of 4CMenB Exposure During Pregnancy,” was an observational pregnancy registry sponsored by GlaxoSmithKline. It was designed to collect information about women exposed to 4CMenB and their infants. The record describes eligibility as receipt of at least 1 dose within 30 days before the last menstrual period or at any time during pregnancy. Exposure could be reported through self-enrollment, enrollment by a healthcare provider with the woman's consent, or anonymous reporting of pregnancy exposures and outcomes by healthcare providers within their network or health maintenance organization.

The registry record lists enrollment of 2. Its recorded start date is 2016-01-31, and its primary completion date is 2019-11-30. The status is listed as COMPLETED. However, the primary outcome entry states that data were not collected because the enrolled participants did not complete the study. These statements describe different parts of the registry record; the record does not explain the discrepancy or clarify what completion refers to.

The study has one exposure group, pregnant women exposed to 4CMenB. It does not report a comparator group or a randomized allocation process. The record lists four outcome measures, including MCM as the primary outcome and spontaneous abortions and still births as secondary outcomes. It reports zero analyses. A statistical analysis plan, outcome definitions beyond the primary outcome label, and details of planned analyses are not reported in the registry record.

Follow-up was intended to continue until the end of the pregnancy. The record does not establish that this follow-up was completed for the enrolled participants. It also does not report a sample-size justification for the registry's own design. Any sample-size planning illustration based on an observed effect would be distinct from the registry's design rationale, and no observed effect is available in the recorded primary outcome.

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: Data was not collected for this outcome measure as the enrolled participants did not complete the 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.

6. Primary Endpoint

The registry lists the primary outcome as Major Congenital Malformation (MCM), measured over At registry enrollment.

The named primary endpoint is major congenital malformation (MCM), with the timeframe stated as at registry enrollment. The registry record does not provide an operational definition of MCM, describe how cases would be identified or classified, or state a denominator for an outcome rate. Most importantly, it explicitly says that data were not collected for this outcome because the enrolled participants did not complete the study. There is therefore no primary-outcome count or estimate to interpret.

General: A primary endpoint gives a study a principal outcome around which its main question and reporting are organized. A clearly defined endpoint can help readers understand what is being counted, in whom, and over what period. In a pregnancy registry, an outcome such as MCM is intended to characterize an outcome of interest among pregnancies with the exposure being studied. Interpretation depends on complete outcome ascertainment and a stated definition; without these, it is not possible to determine how consistently the outcome was assessed or what an estimate would represent.

The timeframe “at registry enrollment” describes when the endpoint was framed for assessment, but the record does not explain the timing or procedure for assessment. Spontaneous abortions and still births appear as secondary outcomes, but no outcome data or definitions for them are reported in the registry record. The listed endpoint therefore communicates the intended focus, not a measured result.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The record describes an observational registry, not a randomized comparison. Exposure is defined by receipt of 4CMenB within a specified period around pregnancy, while enrollment could occur through a woman or a healthcare provider. Since no control group is reported and allocation is not stated, the registry does not support a direct randomized contrast between exposed and unexposed groups. Its intended role was to collect and describe pregnancy and infant outcomes among people with the specified exposure.

What does observational mean?

General: In an observational study, researchers record exposures and outcomes rather than assigning participants to treatment groups by random allocation. Such a design can describe what happened among enrolled participants. When a comparison is available, differences may also reflect factors other than the exposure; causal interpretation therefore requires assumptions and information about potential sources of bias. In this registry, no comparator is reported, so even a between-group association is not available from the record.

What can an outcome estimate tell us?

General: An outcome estimate summarizes observed events in a defined population. Its interpretation depends on a clear outcome definition, a known denominator, and adequate outcome ascertainment. A confidence interval, when reported, describes statistical uncertainty around an estimate under the analysis assumptions; it does not correct for missing outcomes, selection into the registry, or other sources of bias. This registry reports no primary-outcome estimate or confidence interval because the outcome data were not collected.

Why does missing outcome information matter?

General: Missing outcome data reduce the information available for estimating an outcome. If missingness is related to participant characteristics or outcomes, analyses restricted to observed records can be unrepresentative. The registry record does not report why participants did not complete the study, which participants had follow-up, or whether any missing-data method was used. Because the primary outcome was not collected, readers cannot evaluate the extent or pattern of missingness beyond the record's statement.

What does the analysis count show?

The record lists zero analyses. It does not describe a statistical analysis plan, an inferential method, an adjustment strategy, or subgroup analyses. These methods are not reported in the registry record. General: A statistical test or model cannot create outcome information that was not collected. Even a suitable analysis method would need observed outcomes and a clearly defined analysis population. No such primary-outcome analysis is reported.

How should planning calculations be understood?

The registry record describes assumptions for a planning illustration: a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of an observed effect. These are described as planning assumptions, not as the registry's own design or analysis plan. The record does not report a control arm or an observed primary effect, and its primary outcome data were not collected. Consequently, those assumptions do not establish that the registry was designed with two arms, nor do they yield an observed treatment effect. General: Sample-size calculations are planning tools that estimate the number of observations needed under stated assumptions; they are not evidence that a study achieved a particular power after data collection. A planning illustration should not be interpreted as observed power or as a result.

The record gives an enrollment count of 2, but it does not establish that these participants contributed complete outcome data. Enrollment and analysis populations are distinct: enrollment refers to entry into a study, whereas an analysis population depends on the outcomes and eligibility rules used for a particular analysis. The record does not report an analysis population for MCM or any other outcome. As a result, no denominator for outcome estimation can be identified.

General: Over-dispersion is variability greater than a statistical model's assumptions would anticipate. It can make standard errors too small if ignored, leading to confidence intervals that are too narrow and tests that are too optimistic. The registry record does not report a count model, a dispersion assessment, or an outcome analysis involving this issue. This concept is therefore general context rather than a description of a method used in this registry.

Overall, the methods information supports a design-level reading only. The study was intended as a pregnancy exposure registry, but the record does not document completed primary-outcome ascertainment or an analysis of that outcome. No statistical method can be attributed to the registry beyond the planning assumptions described for an illustration.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists four outcome measures, identifies MCM as the primary outcome, and lists spontaneous abortions and still births among the secondary outcomes. It does not provide results for these outcomes. It also reports zero analyses. A multiplicity adjustment or strategy for handling multiple outcomes is not reported in the registry record.

General: When a study tests several outcomes or performs many comparisons, the chance of at least one apparently notable result can increase. Prespecifying a primary outcome and analysis can help distinguish the main question from exploratory analyses. Adjustment methods may be used in some settings, but their appropriateness depends on the study aims and analysis plan. The registry record does not report whether any such methods were planned.

The primary outcome entry says data were not collected because enrolled participants did not complete the study. The record does not describe the number of participants with completed follow-up, the extent of missing information for secondary outcomes, or how missingness was handled. It does not report imputation, sensitivity analyses, or an analysis restricted to participants with observed outcomes. These details are not reported in the registry record.

Nor does the record define an analysis population or explain how participants would be included in analyses. General: An analysis population specifies which participants contribute to a particular estimate. Clear definitions help readers understand the denominator and assess whether exclusions might affect interpretation. Here, the enrollment count alone cannot be treated as an outcome denominator, because primary-outcome data were not collected and completed follow-up is not documented.

The record's COMPLETED status does not resolve these gaps. Its primary outcome entry separately states that enrolled participants did not complete the study, and the record does not explain the relationship between these statements. Thus, neither multiplicity handling nor missing-data methods can be evaluated from the registry record.

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

The registry record establishes that NCT02640677 was intended to monitor pregnancy and infant outcomes after 4CMenB exposure and that enrollment was 2. It identifies MCM as the primary outcome and spontaneous abortions and still births as secondary outcomes. These details describe the study question and its intended scope; they do not constitute outcome findings.

The central limitation for interpretation is explicit: the record says data were not collected for the primary outcome because the enrolled participants did not complete the study. No MCM estimate, secondary-outcome estimate, or comparison is reported. Readers therefore cannot use this record to quantify the frequency of the listed outcomes among enrolled participants or to compare those outcomes with another population.

General: A lack of a reported estimate is not evidence that an outcome occurred or did not occur. Similarly, a zero shown in an event-summary count is not, by itself, proof that no event occurred in the population of interest; its meaning depends on how events were collected and which participants were followed. The record does not explain the completeness of adverse-event reporting, and its primary outcome data were not collected.

The observational design also limits what could be concluded even if outcome data had been available. Without a reported comparator, the record could describe outcomes after exposure but could not directly estimate a contrast with an unexposed group. Because allocation is not stated and the registry is not a randomized comparison, the record does not provide a basis for attributing outcomes to the exposure.

In short, the posted information documents an intended registry question and incomplete outcome ascertainment. It does not establish the presence, absence, frequency, or cause of MCM or other pregnancy outcomes. The COMPLETED status should be read alongside the note that enrolled participants did not complete the study; the registry record does not explain that inconsistency.

12. Why This Trial Matters Statistically

Pregnancy exposure registries address questions that may be difficult to study through randomized allocation. The record describes a way for women and healthcare providers to report 4CMenB exposure and intended follow-up of women and infants until the end of pregnancy. It also defines an exposure window that includes 30 days before the last menstrual period as well as exposure during pregnancy. These design features show how the registry sought to identify relevant exposures and outcomes.

The statistical value of a registry depends on more than a clear question. It also requires adequate enrollment, outcome definitions, follow-up, and a transparent account of missing information. In this record, enrollment was 2, and the primary outcome data were not collected because the enrolled participants did not complete the study. Those details prevent quantitative estimation of the primary endpoint, regardless of the importance of the question.

The record is also a useful example of why study status and analyzable results should be distinguished. The status is COMPLETED, but the primary outcome entry says participants did not complete the study. Without an explanation, the status cannot establish that the intended follow-up or outcome collection was completed. Clear reporting of participant flow and outcome availability would be needed to resolve the issue.

General: Statistical methods can quantify uncertainty when outcomes are observed, but they cannot replace missing data or create a comparison group. A planning calculation is also different from an analysis of observed outcomes. In this registry, the record describes planning assumptions but does not report primary-outcome data or analyses. The statistical lesson is therefore about the limits of interpretation when the registry's intended outcome is unavailable, rather than about an estimated safety effect.

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 principal trial-specific limitation is that no data were collected for the primary outcome, MCM, because the enrolled participants did not complete the study. Enrollment was 2, but the record does not state how many participants had any completed follow-up or provide outcome denominators. This prevents estimation of the primary endpoint and leaves the listed secondary outcomes without reported results.

The registry record does not reconcile its COMPLETED status with its statement that enrolled participants did not complete the study. It does not explain what completion means in this context, why participants did not complete the study, or whether outcome data were available through any other reporting route. Those details are not reported in the registry record.

No comparator group is reported, and the record identifies the study as not a randomized comparison. Accordingly, the registry cannot support a direct comparative estimate from the reported information. The record also does not report an operational definition for MCM, detailed methods for outcome ascertainment, or an analysis plan. It lists four outcome measures but reports zero analyses, so neither outcome-level estimates nor multiplicity procedures can be assessed.

The adverse-event summary lists zero serious and other event counts in its at-risk and affected fields, and zero deaths. The record does not explain the scope or completeness of those counts. Given the statement that participants did not complete the study, those entries should not be interpreted as a comprehensive finding that no events occurred.

Finally, the registry record does not provide a sample-size justification for its own design or describe an analysis population. Planning assumptions for an illustration do not resolve these omissions and do not substitute for observed outcomes. Taken together, these limitations mean that the record documents the intended registry question but does not provide data sufficient to estimate the outcomes it set out to monitor.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Safety of 4CMenB Exposure During Pregnancy — NCT02640677.
• Registry record last updated 2020-09-03; status last verified 2020-09.
• Results first posted 2020-09-03.
• 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

NCT02640677, “Safety of 4CMenB Exposure During Pregnancy,” was an observational registry sponsored by GlaxoSmithKline. It was intended to describe health outcomes among pregnant women in the United States exposed to 4CMenB within 30 days before their last menstrual period or at any time during pregnancy, and to follow women and infants until the end of pregnancy.

The registry record lists enrollment of 2, a start date of 2016-01-31, a primary completion date of 2019-11-30, and status COMPLETED. MCM was the primary outcome; spontaneous abortions and still births were listed as secondary outcomes. The primary outcome entry states that data were not collected because the enrolled participants did not complete the study. The record lists zero analyses and does not report outcome estimates or a comparator group.

The record does not explain the difference between its COMPLETED status and the statement that participants did not complete the study. Its information supports description of the intended design and the absence of primary-outcome data, not a quantitative conclusion about pregnancy outcomes after exposure.