Postplacental Mirena IUD Insertion and Estimating Expulsion Rates.: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Postplacental Mirena IUD Insertion and Estimating Expulsion Rates. (NCT01230242), a na na study. The primary outcome is Number of Participants Who Expelled IUDs by12 Weeks Postpartum.

2. Clinical Question

3. Trial Design

NCT01230242 is registered as an experimental study of Mirena IUD placement immediately after delivery. Its official title describes examining insertion and estimating expulsion rates immediately after placental delivery. The listed intervention is a levonorgestrel intrauterine device, and the arm description identifies immediate post-delivery placement as the study approach.

The design is single-group, with allocation recorded as NA and masking recorded as none. There is no randomized allocation or concurrent comparison arm in the registry record. The study description says the investigators intended to compare the postplacental expulsion-rate estimate with rates reported in the literature for insertion at 6 weeks postpartum. That proposed external comparison is not a randomized or like-for-like control comparison, and the registry record does not provide the literature estimates or a formal comparative analysis.

Enrollment is recorded as 4. The study start date is 2010-09-07, the primary completion date is 2010-10-27, and the status is terminated. The reason for termination, the number of participants who completed follow-up, and the follow-up data available for each participant are not reported in the registry record. The listed primary outcome concerns expulsion up to 12 weeks postpartum, but the record does not state whether every enrolled participant was followed for that full period.

The record lists one outcome measure and no analyses. It does not report a protocol-level statistical analysis plan, sample-size justification, interim analyses, or a detailed account of analysis populations. The design and enrollment therefore support a description of the study’s intended question, but not an estimate of expulsion from the posted outcome data.

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: Only 4 subjects were consented out of the 20. Of those 4 only 3 had the IUD inserted.

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 Number of Participants Who Expelled IUDs by12 Weeks Postpartum, measured over up to 12 weeks postpartum.

The primary endpoint is the count of participants who expelled their IUD by 12 weeks postpartum. It is defined as a participant count, with the stated timeframe extending up to 12 weeks after delivery. The record does not specify a more detailed operational definition of expulsion, how it was assessed, or how uncertain cases were classified.

A count endpoint describes how many participants in the study experienced the event, rather than measuring the timing or severity of expulsion. For a single-group study, an event count can describe what occurred among the enrolled participants if the outcome and follow-up data are reported. It does not, by itself, establish whether the rate differs from another insertion strategy or from a rate observed in another population.

The registry record does not report the primary endpoint count. It therefore does not provide an observed expulsion estimate, nor information about the precision of such an estimate. The study description identifies expulsion as the principal question, but the endpoint definition alone is not a result. Without the event count and relevant follow-up information, the posted record cannot show how many participants experienced expulsion by the specified time.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a count endpoint describe?

The primary measure is a count of participants who experienced IUD expulsion by 12 weeks postpartum. A count is a direct summary of the number of people with the event in the defined study group. To interpret it, readers generally need to know both the count with the event and the number of participants whose outcomes were observed. The registry record gives enrollment of 4 but does not give the primary event count or describe the completeness of follow-up. As a result, neither the observed proportion nor its uncertainty can be read from the posted outcome information.

In general, binary outcomes classify each participant according to whether an event occurred during a specified period. A participant count is one way of reporting such an outcome. It does not communicate when an event happened within the period, how severe it was, or what happened after it. Those details would require additional outcome definitions or results, which are not reported in the registry record.

Why does the design affect the interpretation?

This is a single-group study, with allocation recorded as NA and masking recorded as none. A single group can describe outcomes among its enrolled participants if results are available. It cannot provide a randomized estimate of the difference between immediate post-delivery insertion and insertion at 6 weeks postpartum, because the registry record contains no concurrent comparison group. The study summary’s planned comparison with literature rates is distinct from a randomized comparison within the study. Differences between an enrolled group and external reports may reflect differences in participants, settings, follow-up, or outcome measurement; the record does not provide enough information to evaluate those issues.

General statistical principle: a comparison is most interpretable when groups are defined and observed under comparable conditions. Random allocation can help balance factors that might influence outcomes, while a single-group design cannot use randomization to balance a comparator group. This does not make a single-group count meaningless, but it limits what can be concluded from it. In this record, the primary count itself is not posted, so even a descriptive estimate is unavailable.

What would uncertainty measures add?

General statistical principle: a confidence interval gives a range of values compatible with the observed data under a specified statistical method. It communicates precision as well as the point estimate. Wider intervals indicate less precision; small studies often provide limited information for estimating event frequencies. A confidence interval is not a guarantee that the true value lies in the interval, and it cannot repair missing outcome data or a design without a concurrent comparator.

No confidence interval, standard error, p-value, or primary-outcome analysis is reported in the registry record. These quantities cannot be inferred from enrollment alone. Because the event count is missing, the record does not establish a point estimate around which an interval could be interpreted. Nor does the absence of an analysis entry demonstrate a particular result; it means that an analysis is not reported in the registry record.

How should planning calculations 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. Those are assumptions for hypothetical planning calculations, not stated features of this single-group study. The illustrations do not change the trial design, and they are not observed power. The record gives no sample-size justification for the actual study, and the primary endpoint result needed to define an observed effect is not reported. No specific planning estimate can therefore be interpreted as evidence about the enrolled participants.

General statistical principle: power is a design-stage probability tied to assumptions about an effect, variability, significance level, and sample size. A calculation based on an observed result is not a substitute for a prespecified design justification and should not be read as the probability that a finding is true. Planning scenarios can show how design requirements change under different assumed effects, but they do not establish an effect in the data.

What do the posted analyses establish?

The registry lists 0 analyses. This means an analysis is not reported in the registry record; it does not establish that investigators did not conduct any analysis outside the record. There is no reported model, adjustment strategy, inferential test, or interval estimate for the primary outcome. Since the study is single-group, no comparative effect estimate is posted. Any statistical conclusion about the primary endpoint would require results that are absent from the registry record.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Mirena IUD Placement Immediately Post-delivery")
n      <- c(4)
events <- c(1)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Mirena IUD Placement Immediately Post-delivery  4  1  25.0  0.6  80.6  4.6  69.9  5.3  71.6

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists one outcome measure, identified as the count of participants who expelled IUDs by 12 weeks postpartum. The study summary also mentions secondary outcomes, including endometritis, uterine perforation, continuation, and pregnancy, among others. Their definitions, timeframes, results, and relationship to the listed outcome measure are not reported in the registry record. The record lists 0 analyses, so it does not provide a set of reported tests or estimates on which to assess multiplicity.

General statistical principle: when a study examines several outcomes or performs several statistical tests, the chance of at least one apparently notable result can increase if no strategy accounts for the multiple examinations. A multiplicity plan may identify a primary outcome, set testing priorities, or adjust interpretation across tests. Whether such a plan was used in this study is not reported in the registry record. The presence of a designated primary outcome does not by itself establish how any additional outcomes were handled.

Information about missing data and analysis populations is also limited. Enrollment is 4, but the number with complete follow-up, the number included in each outcome analysis, and any missing-data approach are not reported in the registry record. The primary timeframe is up to 12 weeks postpartum, but the record does not state whether each participant contributed outcome information through that period. It also does not define an intention-to-treat, per-protocol, or other analysis population.

General statistical principle: missing outcome data can affect both the number of participants contributing to an estimate and the interpretation of that estimate. The direction and size of any effect depend on why information is missing and how missingness is handled. Without information about follow-up and analysis populations, the extent or consequences of missing data cannot be assessed for this record.

12. 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 registry record lists 0 serious adverse events among 4 participants at risk and 0 other adverse events among 4 participants at risk. Deaths are listed as 0. No serious adverse-event terms are listed. These figures describe the adverse-event entries posted for the study; they are separate from the primary endpoint, which concerns IUD expulsion and is not reported.

General statistical principle: an observed count of zero in a small group is not proof that an event is impossible or that the risk is zero. The amount of information about uncommon events depends on the size of the group, follow-up, event definitions, and completeness of reporting. The registry record does not provide detailed safety definitions or a fuller account of safety ascertainment, so the counts should be read narrowly as the posted figures.

The record does not report a comparison group for safety outcomes. These counts therefore cannot establish a difference in safety between immediate placement and another insertion schedule. They also should not be taken as a substitute for the missing expulsion result or as a comprehensive description of every outcome mentioned in the study summary.

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

The record establishes that a study of immediate post-delivery Mirena IUD placement enrolled 4 participants and was later recorded as terminated. Its stated primary outcome was the number of participants who expelled an IUD by 12 weeks postpartum. The registry record does not report that number, so it does not provide an observed expulsion estimate. The study’s stated aim and planned external comparison are not results.

As a result, the posted information cannot show whether expulsion was more or less frequent than with insertion at 6 weeks postpartum, or whether any observed rate met a threshold for acceptability. The record contains no concurrent control group, and it gives no literature rates or comparative analysis. Even a reported count in the single study group would not, on its own, establish a causal difference between insertion timings.

The listed safety counts are 0 serious adverse events among 4 participants at risk, 0 other adverse events among 4 participants at risk, and 0 deaths. They describe the registry’s safety entries for this small group. They do not answer the primary endpoint question, and zero posted cases should not be interpreted as proof that adverse events cannot occur.

General statistical principle: interpretation depends on the match between the question, the design, and the available results. A study may be designed to estimate an event frequency, but without the outcome count and follow-up information, the estimate cannot be evaluated. A comparison requires appropriate data from both groups, while precision requires an estimate and an uncertainty measure. Neither a comparative effect nor a primary-outcome uncertainty measure is reported in the registry record.

The appropriate conclusion is limited: the registry records the intended question, the single-group design, enrollment, status, and adverse-event counts, but not the primary result. The reason for termination, completeness of follow-up, and any unposted analyses are not reported in the registry record.

14. Why This Trial Matters Statistically

This study illustrates why the design and completeness of registry results matter when interpreting an event-rate question. The intended outcome is clear in broad terms: a count of participants with IUD expulsion by 12 weeks postpartum after immediate post-delivery placement. But an endpoint definition is not an endpoint result. Without the event count, readers cannot assess even the descriptive frequency the study set out to estimate.

The single-group design also distinguishes an estimate from a comparative conclusion. The study summary refers to rates in the literature for insertion at 6 weeks postpartum, but no concurrent comparison group or literature values are reported in the registry record. A proposed external comparison should not be mistaken for a randomized contrast. This distinction is important whenever the scientific question is framed around whether one approach has a higher event frequency than another.

The enrollment of 4 underscores the limited amount of information represented in the record, though sample size alone cannot supply the missing result. General statistical principle: estimates from small groups tend to be imprecise, particularly for event outcomes, and uncertainty should be communicated rather than hidden behind a single count. Here, no primary estimate or interval is available to judge.

The registry also records 0 serious adverse events, 0 other adverse events, and 0 deaths among the stated groups at risk. These entries are relevant but answer a different question from expulsion. Keeping endpoint categories separate prevents safety counts from being treated as evidence about the primary outcome.

Finally, the terminated status is a meaningful feature of the record, but its cause is not stated. Statistical interpretation should remain tied to what the registry actually documents, without assigning a reason for termination or assuming what unreported analyses might have shown.

15. 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 is that the registry record does not report the primary outcome count. Although the endpoint is defined as participants who expelled IUDs by 12 weeks postpartum, the number experiencing expulsion is absent. No estimate or interval for that outcome can therefore be interpreted.

Enrollment was 4, and the study had a single group. There is no concurrent comparator, no randomized allocation, and no posted comparative analysis. The study summary’s intended reference to literature rates for 6-week postpartum insertion does not supply a trial control group or a documented comparative result. The registry record also does not report the literature values, so the planned context cannot be evaluated from this information.

The study status is terminated, but the reason is not reported in the registry record. The number of participants who completed follow-up, the completeness of outcome ascertainment, and any departures from the intended follow-up period are not reported. The primary timeframe is up to 12 weeks postpartum, but there is no participant-level or aggregate account of follow-up duration.

Other limitations include the absence of a detailed operational definition of expulsion, no reported statistical analysis, and no described analysis population or missing-data method. The record lists secondary outcomes in the study summary but does not report their results or how multiplicity was addressed. It does not report a sample-size justification, interim analyses, or the reason enrollment ended at 4. These omissions prevent assessment of the study’s planned precision, the handling of incomplete data, and the interpretation of any unposted analyses.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Postplacental Mirena IUD Insertion and Estimating Expulsion Rates. — NCT01230242.
• Registry record last updated 2021-12-17; status last verified 2021-12.
• Results first posted 2021-12-17.
• 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.

19. Record Summary

NCT01230242 is a terminated, single-group study of Mirena IUD placement immediately after delivery. Enrollment was 4. The stated primary outcome was the number of participants who expelled IUDs by 12 weeks postpartum, but the outcome count and any analysis are not reported in the registry record.

The record lists 0 serious adverse events among 4 participants at risk, 0 other adverse events among 4 participants at risk, and 0 deaths. It does not report a concurrent comparator, the reason for termination, follow-up completeness, or results for the secondary outcomes mentioned in the study summary. The registry therefore documents the study’s aim and selected design details, but not a primary estimate of expulsion or a comparative conclusion.