Timing of Postpartum Depot Medroxyprogesterone Acetate Administration on Breastfeeding, Contraceptive Continuation, and Depression: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Timing of Postpartum Depot Medroxyprogesterone Acetate Administration on Breastfeeding, Contraceptive Continuation, and Depression (NCT01463202), a randomized phase 4 study. The primary outcome is Duration of Breastfeeding Among Women Who Plan to Breastfeed Their Infants After Postpartum or Delayed (4-6 Weeks Postpartum) Initiation of DMPA.

2. Clinical Question

3. Trial Design

The registry describes a randomized trial comparing two timing strategies for DMPA after delivery. One arm is labeled DMPA postpartum, with the summary specifying administration prior to hospital discharge. The other is labeled DMPA at 4-6 weeks after delivery. The record lists the allocation as randomized and masking as none. It lists the trial status as completed and enrollment as 184.

The design is intended to address a question about timing among women planning to breastfeed and use DMPA. The primary outcome description concerns whether participants were breastfeeding at repeated postpartum time points, rather than a single measurement of breastfeeding at one visit. The listed time points are 2, 4, 6, 8 12, 16, 20, 24, and 28 weeks postpartum. Secondary outcomes concern highly effective contraception, postpartum depression, and breastfeeding exclusivity.

There is an inconsistency in the record’s design metadata: it identifies allocation as randomized and describes two arms, while its model classification is single-group. The posted information does not explain that difference. It also does not report details about the randomization procedure, allocation concealment, or how participants were assigned in practice. Those details should not be inferred from the word “randomized.”

The record lists a start date of 2011-11 and primary completion on 2017-02-13. It does not give a fuller account of recruitment or follow-up procedures. Although the trial is marked completed, completion status alone does not establish that all planned outcome data were collected or analyzed. The registry record does not report a protocol, a rationale for the enrollment target, or a statistical analysis plan.

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: Since participants could be recruited antepartum but may have changed their mind about breastfeeding or DMPA use post-partum, eligibility criteria were re-assessed postpartum, prior to randomization, thus the number of women enrolled in the study (184) does not equal the number of women randomized (157).

Overall Study

Analysis population for the primary outcome, as defined in the registry: 1 ppt withdrawn postrandomization due to enrollment violation (did not meet eligibility criteria)

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 Duration of Breastfeeding Among Women Who Plan to Breastfeed Their Infants After Postpartum or Delayed (4-6 Weeks Postpartum) Initiation of DMPA, measured over 2, 4, 6, 8 12, 16, 20, 24, and 28 weeks postpartum.

The primary endpoint is described as the count of participants with any breastfeeding at specified postpartum time points. It is not a measure of breastfeeding exclusivity: exclusivity appears separately among the secondary outcomes. The registry frames the outcome as duration of breastfeeding, but the posted description operationalizes it through reports of any breastfeeding at repeated time points. That distinction matters because a participant may be breastfeeding at one assessment and not another; a sequence of such observations gives a different picture from a single summary of duration.

Repeated time points can be useful for describing how breastfeeding status changes over follow-up. They can show whether group patterns are similar at some assessments and different at others, if those results are reported. However, the registry information does not supply those outcome counts, a summary effect, or a comparison across time. It also does not state how the primary outcome was reduced to a single analysis. The record explicitly indicates that the primary outcome has several categories or time points and is not reduced to one comparison.

In general, choosing an endpoint that reflects the research question helps keep interpretation focused. Here, the question concerns breastfeeding duration in relation to the timing of DMPA, while the listed measure is any breastfeeding at scheduled postpartum assessments. The endpoint can describe breastfeeding status at those assessments, but the record does not establish a continuous duration measure or explain how missing assessments were handled.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The record identifies a randomized allocation, no masking, a count-of-participants outcome, and repeated postpartum assessment times. It does not report the analysis method used for the primary endpoint. The explanations below are general statistical context for understanding what would be needed to interpret a repeated binary outcome; they do not describe an analysis confirmed by this registry record.

What does a randomized comparison contribute?

In general, random assignment is intended to make treatment groups comparable at the point of assignment, apart from chance variation. It supports interpretation of a between-group contrast when the assigned groups, outcome definitions, follow-up, and analysis are described. Randomization does not guarantee that follow-up is complete, that every outcome is measured consistently, or that a particular statistical model is appropriate. The record says allocation was randomized, but the method of sequence generation and allocation concealment is not reported in the registry record.

The arms differ in the planned timing of the same drug: postpartum administration versus administration at 4-6 weeks after delivery. This makes the timing contrast central. A comparison of the arms would need to state whether participants are analyzed according to assigned timing, actual timing, or another analysis population. That choice is not reported in the registry record.

How can repeated binary outcomes be analyzed?

At each listed assessment, the outcome is whether a participant reports any breastfeeding. In general, this is a binary status at a particular time, while measurements from the same participant across follow-up are related. An analysis that treats every assessment as unrelated to the others may fail to account for that within-participant dependence. Methods for repeated binary outcomes can model the outcome over time while allowing observations from a participant to be correlated. The chosen model, its assumptions, and its handling of participants with incomplete assessments are not reported in the registry record.

Another general approach is to report a separate group comparison at each assessment. That can be easy to read, but it creates multiple comparisons and may make a single overall conclusion difficult to define. A summary over time may instead target a prespecified overall effect or a pattern of change. The registry does not report which approach was planned or used, and it does not identify a single primary contrast across the listed time points.

What role do effect estimates and uncertainty play?

In general, a group difference or other effect estimate gives the scale and direction of a contrast. A confidence interval shows the range of values reasonably compatible with the data and the stated method. A p-value addresses compatibility with a specified null model; it does not describe the size or practical importance of an effect. For repeated outcomes, the meaning of any estimate depends on the model and the contrast being reported. The registry information does not report a primary effect estimate, confidence interval, or p-value, so there is no basis to judge magnitude, precision, or statistical evidence for a difference.

Over-dispersion is a general concern when count or binary data vary more than a model assumes. If a method assumes less variability than the data contain, its uncertainty estimates can be too narrow. Approaches that account for extra variation may be appropriate in some settings, but the record does not report a model or evidence of over-dispersion. It would be speculative to say that this issue arose or that a particular adjustment was used.

How should the planning illustrations be read?

The sample-size section describes planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. For non-time-to-event outcomes, its intended quantity is participants per arm for 80% power; time-to-event illustrations instead give the total number of events. These are planning calculations, not results from the trial and not observed power. The registry record does not report the trial’s own sample-size justification or establish that these illustration assumptions were used to design the trial. The resulting planning values should not be mistaken for enrolled or analyzed participants.

In general, a planning calculation depends on assumptions about the effect to detect, variability or event frequency, significance level, allocation, and analysis method. A calculation based on an observed effect is especially dependent on that effect estimate and should not be treated as proof that a study was adequately powered. The results of the trial and the uncertainty around them remain essential for interpretation. Since the primary outcome comparison is not reported, the planning illustrations cannot fill that evidentiary gap.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome is assessed at multiple postpartum time points: 2, 4, 6, 8 12, 16, 20, 24, and 28 weeks postpartum. The registry explicitly notes that the outcome has several categories or time points and is not reduced to one comparison. This leaves an important interpretive question: would the trial treat each time point as a separate endpoint, or would it use a prespecified summary across follow-up? The statistical plan is not reported in the registry record.

In general, testing several outcomes or time points can increase the chance of finding an apparently notable result by chance if each comparison is interpreted independently. A prespecified approach to multiplicity can help define which result is primary and how evidence across comparisons should be assessed. The registry information does not report a multiplicity strategy, a primary contrast among time points, or an adjustment method. It would not be appropriate to assume either that an adjustment was made or that no adjustment was intended.

The listed secondary outcomes concern highly effective contraception, postpartum depression, and breastfeeding exclusivity. The record does not provide their outcome results or describe how testing across primary and secondary outcomes was addressed. It also does not report interim analyses or stopping rules.

For missing data, the primary outcome description notes that 1 participant was withdrawn postrandomization because of an enrollment violation. That note does not explain whether the participant was excluded from all analyses, whether data collected before withdrawal were retained, or how missing breastfeeding assessments for other participants were handled. The record does not report the analysis population, missing-data assumptions, or sensitivity analyses. These omissions prevent a full assessment of how the reported population, if any, relates to the randomized groups and how incomplete follow-up might affect the results.

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 registry’s safety entries list the number at risk and the number affected in each arm. For DMPA Postpartum, 79 participants are listed as at risk for serious adverse events and 0 as affected; for DMPA at 4-6 Weeks After Delivery, 78 are listed as at risk and 0 as affected. The entries also list 0 participants affected by other adverse events and 0 deaths in each group. These are counts in the registry record, not a comparison of event rates adjusted for follow-up or exposure.

A zero in the affected column means that the record reports no events in that category for the listed group. It does not establish that no event occurred outside the collection or reporting process, and it does not by itself establish equivalence between arms. Interpretation of safety counts generally depends on how events were defined, collected, and followed over time. Those details are not reported in the registry record. The record also does not list serious adverse event terms. The figures should therefore be read as the posted counts, not as a comprehensive conclusion about safety.

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

This record is useful for identifying a focused research question: whether the timing of postpartum DMPA administration is related to breastfeeding duration among women planning to breastfeed and use DMPA. It describes a randomized comparison of administration postpartum and at 4-6 weeks after delivery, and defines the primary outcome as any breastfeeding at several postpartum assessments. It also identifies secondary questions about contraception, postpartum depression, and breastfeeding exclusivity.

However, the registry information does not report the primary outcome counts or an effect estimate. It therefore cannot establish whether the groups differed in breastfeeding at any assessment, the direction or size of a difference, or how precise an estimate would be. The completion status and enrollment entry do not answer those outcome questions. Nor can the safety counts be used to draw conclusions about breastfeeding outcomes.

In general, a trial result should be interpreted through the outcome definition, the comparison actually estimated, uncertainty around that estimate, and the extent of missing data. A reported difference would describe the data under the analysis used; it would not automatically establish a broad effect beyond the population and setting studied. Here, the analysis and outcome comparison are not reported in the registry record, so even that narrower interpretation is unavailable.

The sample-size illustrations elsewhere on the page are planning aids rather than evidence that an effect was detected or that a result is precise. They are not observed power. The appropriate reading is therefore limited: the registry describes the design and intended outcomes, while the posted information does not allow a conclusion about the primary outcome comparison. This is an account of what the record contains, not medical advice or a recommendation about contraceptive timing.

13. Why This Trial Matters Statistically

Statistically, the trial raises a question about timing rather than a contrast between different drugs. That distinction affects how the comparison should be framed: the arms are described as receiving DMPA at different postpartum times. The record also makes clear that breastfeeding status was intended to be assessed repeatedly, which creates an analysis challenge beyond comparing a single endpoint.

Repeated binary measurements can be informative because they describe status across follow-up. They also require care: observations from the same participant are generally related, and a collection of time-specific comparisons can raise multiplicity questions. A clear analysis plan would identify the primary contrast, the treatment of repeated observations, and how incomplete assessments are handled. Those details are not reported in the registry record, so readers cannot assess whether the planned method matched the structure of the outcome.

This case also illustrates why a completed trial record is not necessarily a complete statistical report. The registry identifies enrollment, arms, time points, secondary outcomes, and a small note about a postrandomization eligibility withdrawal. Yet the primary comparison and its uncertainty are not reported. Without those elements, readers can understand the question and some design features but cannot evaluate the outcome evidence.

Finally, the record’s mismatch between randomized two-arm descriptions and a single-group model classification is a reminder to check internal consistency in registry metadata. It does not resolve the results question, but it cautions against treating every design label as interchangeable with the arm descriptions. Precise statistical interpretation depends on knowing what was assigned, what was measured, who was analyzed, and what contrast was estimated.

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 central limitation for interpreting this trial from the registry record is that the primary outcome comparison is not reported. The outcome is defined at several time points, but the record does not provide counts by arm, an effect estimate, a measure of uncertainty, or a reported test. Consequently, readers cannot assess the magnitude or precision of any difference in breastfeeding status.

The record does not describe the statistical analysis plan, the selected method for repeated outcomes, or the primary contrast across time. It also does not report how multiplicity was handled, whether interim analyses were conducted, or what sample-size justification was used. The planning illustrations are explicitly not the trial’s design calculation, and their assumptions cannot be treated as the original protocol.

Information about missing data and analysis populations is limited. The primary outcome description notes that 1 participant was withdrawn postrandomization because eligibility criteria were not met, but it does not explain the disposition of that participant’s data or describe completeness at subsequent assessments. No account of other missing outcomes or sensitivity analyses is reported in the registry record.

There is also a metadata inconsistency: allocation is listed as randomized and the record describes two arms, while the model classification is single-group. The record does not explain this classification. Details of sequence generation, concealment, adherence to assigned timing, outcome ascertainment, and follow-up procedures are not reported. These limitations do not show that the trial was conducted improperly; they mark what cannot be evaluated from the posted registry information.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Timing of Postpartum Depot Medroxyprogesterone Acetate Administration on Breastfeeding, Contraceptive Continuation, and Depression — NCT01463202.
• Registry record last updated 2018-08-31; status last verified 2018-08.
• Results first posted 2018-03-13.
• 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 record describes a completed randomized trial of postpartum DMPA timing, with enrollment listed as 184 and no masking. The arms compare DMPA postpartum with DMPA at 4-6 weeks after delivery. The primary outcome concerns any breastfeeding at 2, 4, 6, 8 12, 16, 20, 24, and 28 weeks postpartum. Secondary outcomes concern highly effective contraception, postpartum depression, and breastfeeding exclusivity.

The record lists 0 analyses and does not report a primary outcome comparison or its uncertainty. It notes that 1 participant was withdrawn postrandomization for an eligibility violation. Safety entries list 0 serious adverse events, 0 other adverse events, and 0 deaths in each group. The design metadata also identifies the model as single-group despite the randomized two-arm description; the record does not explain that inconsistency. Overall, the registry entries the research question and selected design features, but does not provide the outcome analysis needed to judge the primary comparison.