First Heroes: Engaging Fathers in the First 1000 Days: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for First Heroes: Engaging Fathers in the First 1000 Days (NCT04477577), a randomized na study. The primary outcome is Number of Infants With Rapid Infant Weight Gain.

2. Clinical Question

The central question is whether the number of infants meeting the registry definition of rapid infant weight gain differed between families assigned to the New Parent Engagement Intervention and those assigned to the Safety Control. The registry describes a two-arm randomized trial recruiting through Massachusetts General Hospital obstetrics practices, with the broader goal of engaging fathers during the first 1000 days and influencing health trajectories for mother-father-infant triads from racial/ethnic minority and health disparity populations.

The registry defines rapid infant weight gain as an increase in weight-for-age z-score of >0.67 units between birth and 6-months of infant age. The primary comparison is a count-based outcome, with the posted results giving the number meeting that definition and the number in each group with complete growth data. The registry record does not report details of the intervention components, the safety-control activities, or the exact methods used to implement random assignment. It also does not report the trial’s original statistical question in more detail than the registered outcome description.

3. Trial Design

First Heroes: Engaging Fathers in the First 1000 Days is recorded as a randomized, single-masked, parallel, two-arm study. Its status is completed. Massachusetts General Hospital is listed as the sponsor. The recorded start date is 2020-08-04, and primary completion is recorded as 2023-11-30. The registry lists enrollment as 657. The study summary separately says the study planned to enroll 250 father-mother dyads during the second trimester of pregnancy and intervene through the offspring’s 1-year birthday. The record does not explain the difference between the planned number in the summary and the enrollment figure.

Participants were assigned to the New Parent Intervention or Safety Control. The study summary describes both as added to obstetric and pediatric standard of care. It says recruitment took place in Massachusetts General Hospital obstetrics practices and frames the intended population as mother-father-infant triads from racial/ethnic minority and health disparity populations. The registry’s primary outcome population is narrower in that it consists of infants with complete growth data at birth and 6-months.

The listed primary outcome is the number of infants with rapid infant weight gain, measured from birth to child age 6 months. The registry also lists 27 outcome measures, with 20 secondary outcomes posted. Eight secondary-outcome titles are represented in the registry summary, including repeated entries for some outcomes; the displayed secondary results include maternal postpartum weight retention, maternal diet, and maternal physical activity. The listed outcomes also include maternal adherence to preventive health services and paternal mean body mass index, but results for those measures are not described in the posted secondary results included in this record.

The registry classifies masking as single but does not report which people were masked or how masking was maintained. It does not report the randomization sequence method, allocation concealment, the treatment or control content in detail, or the original statistical analysis plan. Those design details should not be inferred from the intervention names or the outcome summaries.

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

Analysis population for the primary outcome, as defined in the registry: Based on those with complete growth data at birth and 6-months.

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.

Population: Includes all members of mother, father, infant triad.

Only the first 6 of 7 groups are shown.

6. Primary Endpoint

The registry lists the primary outcome as Number of Infants With Rapid Infant Weight Gain, measured over Birth to child age 6 months.

The primary endpoint counts infants who met the registry definition of rapid infant weight gain between birth and age 6 months. The definition is an increase in weight-for-age z-score of >0.67 units over that interval. It is a binary event at the participant level: an infant either meets the stated threshold or does not. The posted result is therefore expressed as a number of infants meeting the definition among infants with complete growth data at both specified ages.

Using a threshold converts changes in a continuous growth measure into an event count. This can make the outcome easier to summarize as a group comparison, but it also means that the result does not describe the full distribution of weight-for-age z-score changes. Infants just on either side of the threshold are counted differently even if their measured changes are close, while variation in changes among infants on the same side is not retained in the event count.

The endpoint focuses on early growth and matches the study’s stated interest in infant health trajectories and obesity-related outcomes. Its interpretation is bounded by the stated ages and the complete-growth-data population. The registry record does not report additional details about how growth was measured, how missing measurements were handled beyond defining the complete-data population, or why this particular threshold was selected. The endpoint indicates how many infants crossed the registered threshold; it is not, by itself, a complete description of later growth, health, or the wider aims of the study.

7. Results Posted in the Registry

• New Parent Intervention - Infant: 15.2% (12/79) versus 30.7% (27/88) on control; risk difference -15.5 percentage points (95% CI -28.0 to -3.0), risk ratio 0.50 (0.27–0.91); unadjusted two-proportion z-test p = 0.018.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Maternal Post-partum Weight Retention

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • New Parent Intervention - Mothers: mean 3.23 versus 3.70 on control; difference -0.47 (95% CI -4.08 to 3.14), standardized effect d = -0.04; z-test p = 0.798.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between New Parent Intervention - Mothers and the control. The interval gives the range of effects that remain compatible with the data.

Maternal Diet

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • New Parent Intervention - Mothers: mean 1.80 versus 1.90 on control; difference -0.10 (95% CI -0.54 to 0.34), standardized effect d = -0.07; z-test p = 0.652.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between New Parent Intervention - Mothers and the control. The interval gives the range of effects that remain compatible with the data.

Maternal Physical Activity

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • New Parent Intervention - Mothers: mean 2.25 versus 2.59 on control; difference -0.34 (95% CI -0.72 to 0.04), standardized effect d = -0.27; z-test p = 0.077.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between New Parent Intervention - Mothers and the control. The interval gives the range of effects that remain compatible with the data.

The posted secondary results cover maternal postpartum weight retention, maternal diet, and maternal physical activity. Across these outcomes, the estimated group differences are modest in their recorded measurement units, and the confidence intervals include zero. The results therefore leave uncertainty about both the direction and magnitude of the underlying group contrasts. Their interpretation is separate from the infant primary outcome because they measure different aspects of health and behavior, in different populations and over different timeframes.

The secondary measures do not directly validate or invalidate the primary finding. Maternal weight retention, diet, and activity may be relevant to the broader study aims, but the registry record does not report analyses establishing a pathway connecting these measures to the infant event outcome. They should not be used as mechanistic explanations for the observed primary contrast. Likewise, the primary result does not imply that every secondary measure should change in the same direction.

The registry lists 27 outcome measures and 20 posted secondary outcomes, while the results summary includes only selected secondary comparisons and reports no analyses for them. Repeated outcome titles and the broader number of outcomes raise a multiplicity consideration: when many outcomes are examined, some estimates may appear notable by chance, even if there is no underlying effect. The registry record does not report a correction or hierarchy for these comparisons.

Because the listed secondary comparisons are unadjusted and no reported analyses are listed, they carry less inferential weight than a clearly prespecified, fully reported confirmatory analysis would. Their intervals and point estimates remain useful descriptive information, but they should be read as exploratory context rather than a coordinated set of definitive tests. The registry record does not state which secondary hypotheses were prespecified, whether all planned secondary measures were analyzed, or how missing observations were handled. Those gaps prevent a full assessment of the secondary evidence as a family.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Maternal Post-partum Weight Retention
• Maternal Post-partum Weight Retention
• Maternal Diet
• Maternal Diet
• Maternal Physical Activity
• Maternal Physical Activity
• Maternal Adherence to Preventive Health Services
• Paternal Mean Body Mass Index

9. Statistical Interpretation

10. Statistical Methods Explained

The primary result is a comparison of event counts between two randomized groups. Each infant with complete measurements at birth and 6-months is classified according to whether the increase in weight-for-age z-score exceeded the registered threshold. This produces an event count and a denominator for each group. The event proportion is conceptually the number meeting the definition divided by the number included in that group, but the explanation relies on the posted counts and reported effect estimates rather than calculating additional values.

What does the risk difference describe?

The risk difference expresses the contrast between the groups as a difference in their event proportions. The posted estimate is -0.155, with a 95% confidence interval from -0.280 to -0.030. Its sign indicates that the intervention group’s observed event proportion was lower than the control group’s in this analysis. The confidence interval gives a range of values compatible with the data under the calculation’s assumptions. A risk difference is expressed on the absolute event-proportion scale, so it conveys a different aspect of the contrast from a relative measure.

How do relative risk and odds ratio differ?

The relative risk compares the event proportions directly; the odds ratio compares event odds. The posted relative risk is 0.495, and the posted odds ratio is 0.405. Both are below 1 in the direction of fewer observed events in the intervention group. They use different scales and should not be read as interchangeable quantities. In particular, an odds ratio is not the same quantity as a risk difference or a relative risk. The three estimates all come from the same group counts, so they should not be treated as independent pieces of evidence.

What does the p-value add?

The unadjusted p-value is 0.018. In general, a p-value measures how unusual data at least as incompatible with a null hypothesis would be if that null model and its assumptions were true. It does not indicate the probability that the hypothesis is true, and it does not quantify the size of an effect. The registry does not report the precise test or model used for this comparison, nor does it document a multiplicity plan. The p-value is therefore best described as the posted unadjusted value, not as a complete account of the trial’s inferential strategy.

Why does the complete-data definition matter?

The primary endpoint population is explicitly based on infants with complete growth data at birth and 6-months. The group denominators in the primary result are 79.0 and 88.0, whereas the registry lists overall enrollment as 657. These quantities refer to different descriptions of study size and should not be substituted for one another. The primary estimate describes the infants included in the complete-data outcome population. The registry record does not report whether infants without complete measurements differed from those included, how missing data were addressed, or whether any sensitivity analyses were conducted.

Randomization can support a fair comparison by balancing prognostic factors on average, but the registry record does not give enough detail to assess the sequence generation, concealment, adherence, or analysis population. Random assignment alone does not resolve missing outcome data or guarantee that the analyzed groups retain all advantages of the original assignment. Those questions require methods and participant-flow details that are not reported in the registry record.

How should the secondary comparisons be understood?

The posted secondary results use mean differences for continuous measures. A mean is the arithmetic average within a group, while the standard deviation describes spread among individual observations. The mean difference compares group averages; its confidence interval describes uncertainty in that difference. These summaries do not show the shape of each outcome’s distribution or account for any covariates unless the analysis explicitly does so. The posted secondary comparisons are unadjusted, and no reported analyses are listed for them.

For general interpretation, a confidence interval spanning zero for a mean difference includes both a possible negative and a possible positive group contrast under the interval’s assumptions. That does not prove the groups are identical. It indicates that the data do not pin down the direction and magnitude as precisely as a narrow interval entirely on one side of zero might. The maternal measures are also not substitutes for the infant primary endpoint: they describe distinct outcomes, collected over their own stated timeframes.

The registry record does not report the original analysis plan, the specific statistical tests, covariate adjustments, handling of departures from assumptions, or whether the posted estimates were intended as confirmatory. These absences limit how far statistical interpretation can go. General statistical principles can explain the reported measures, but they cannot fill in undocumented trial procedures.

11. Confidence Intervals and Precision

The primary risk-difference estimate is -0.155, and its 95% confidence interval extends from -0.280 to -0.030. The interval lies on the negative side of zero, matching the direction of the observed counts. Its range indicates uncertainty about the size of the difference: the estimate is not known with the precision of a single fixed value. A confidence interval is a range generated by a method that, over repeated use under its assumptions, would contain the underlying parameter at the stated rate. It is not a statement that a particular value inside this interval has a specified probability of being true.

The relative-risk interval is from 0.269 to 0.910, around an estimate of 0.495. The odds-ratio interval is from 0.189 to 0.868, around an estimate of 0.405. These intervals are on their respective relative scales and should not be compared numerically with the risk-difference interval as though all three measured the same quantity. All three are derived from the same primary group data.

The posted secondary confidence intervals are less precise in relation to their estimated differences. For maternal postpartum weight retention, the mean difference is -0.47 kg, with an interval from -4.078 to 3.138. For maternal diet, the mean difference is -0.1 servings/day, with an interval from -0.535 to 0.335. For maternal physical activity, the mean difference is -0.34 days/week, with an interval from -0.717 to 0.036. Each interval includes zero, so each remains compatible with a range of differences in either direction under the calculation’s assumptions.

Precision depends on the amount and variability of outcome information as well as the analysis. The registry record does not report confidence intervals for every listed outcome or enough information to assess all causes of uncertainty. The intervals should be considered alongside the analysis population, unadjusted status of the comparisons, and lack of reported missing-data analyses.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning illustrations translate selected effect sizes into estimated sample requirements under stated planning assumptions. For the binary primary outcome, the figures are participants per arm, not total participants. For time-to-event outcomes, the general note says figures would be total events; that distinction does not apply to this primary endpoint. The displayed planning scenarios use 100% of the observed effect, 75% of the observed effect, and 50% of the observed effect. The associated estimates are illustrations based on the observed result, not the trial’s original design justification.

The listed assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is the stated fraction of the observed effect. The 80% power column describes the planned chance of detecting an effect of that assumed size if it is present, under the planning model and assumptions. The 90% power column uses a higher target chance of detection under those same assumptions. These are design-planning concepts; they do not describe the probability that this completed trial’s result is correct.

The illustration requires more participants per arm when planning for a smaller effect. For example, the listed primary-outcome figures rise from 115 participants per arm for 80% power at 100% of the observed effect to 513 at 50% of the observed effect. For 90% power, the corresponding listed figures are 153 and 686. Smaller effects are harder to distinguish from random variation, so planning to detect them generally requires more information.

This is not observed power. It is a planning illustration based on the observed effect and stated assumptions, not a retrospective measure of whether the trial was adequately powered. The registry record does not report the original sample-size assumptions or justification, and the displayed planning assumptions should not be attributed to the investigators’ original design.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.307; treatment proportion p₁ = 0.152; average p̄ = 0.229.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.5946 = 1.1653.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.5844 = 0.4918.
4. n = (1.1653 + 0.4918)² / (-0.1549)² = 114.4, rounded up to 115 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
p0 <- 0.306818181818182                          # control proportion
p1 <- 0.151898734177215                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(4477577)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 115 (80% power), 153 (90% power)
 75% of observed effect: n per arm = 217 (80% power), 289 (90% power)
 50% of observed effect: n per arm = 513 (80% power), 686 (90% power)
power.prop.test: 114.4 
Simulated power at n = 115 per arm: 0.808 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry lists 27 outcome measures and indicates that 20 secondary outcomes are posted. Several outcome titles appear more than once in the record, and the posted results include multiple comparisons across different measures. When many outcomes or hypotheses are examined, the chance of at least one apparently unusual result can increase even if all null hypotheses are true. Statistical methods for addressing this issue can include prespecified outcome hierarchies or adjustments, but the registry record does not report whether either approach was used.

The primary comparison has an unadjusted p-value of 0.018. The record does not say whether the primary outcome was protected by a prespecified testing order or whether any adjustment was planned across outcomes. This absence does not change the posted estimate, but it limits the interpretation of the p-value as part of a broader confirmatory testing strategy. The secondary results are also unadjusted, and the record lists no reported analyses for those outcomes.

Missing data are particularly relevant because the primary outcome is defined for infants with complete growth data at birth and 6-months. The registry reports 79.0 and 88.0 infants in the two primary outcome groups. It does not report the number lacking one or both growth measurements, reasons for missingness, whether missingness differed by randomized group, or any imputation or sensitivity analysis. Complete-case results describe those with the required measurements; they do not automatically describe all randomized participants.

The record does not specify the analysis population beyond the complete-growth-data definition for the primary endpoint. It does not state whether analyses followed randomized assignment regardless of intervention participation, whether other exclusions were applied, or how deviations from assigned groups were treated. It also does not report whether the secondary analyses used the same population as the primary analysis. Those details matter because analysis choices can affect the group comparison and its precision.

The registry does not report a statistical analysis plan, a detailed model specification, interim analyses, or a missing-data strategy. These elements should be treated as not reported in the registry record rather than inferred from the posted estimates.

15. 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 safety figures report zero serious adverse events and zero other adverse events in each listed mother, father, and infant group. The reported at-risk counts are 113 mothers in the New Parent Intervention group and 114 mothers in the Safety Control group; the same at-risk counts are listed for fathers. For infants, the at-risk counts are 93 in the New Parent Intervention group and 101 in the Safety Control group. Deaths are recorded as zero in all six groups.

These figures describe what was recorded for the specified at-risk populations. They should not be interpreted as proof that no adverse event of any kind occurred outside the registry’s recorded categories or reporting process. The record does not provide event narratives, definitions beyond the serious and other adverse-event categories, observation durations, or further detail about how safety events were collected and assessed. It also does not explain why the at-risk denominators differ across mothers, fathers, and infants or from the primary outcome denominators.

Safety counts are distinct from the primary growth outcome. The absence of reported events in these categories does not establish a general safety profile or resolve questions beyond the registry’s recorded figures. It is a description of the posted report, with the scope limited to the groups and categories listed.

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

The primary outcome data show fewer infants meeting the registered rapid-weight-gain definition in the New Parent Intervention group than in the Safety Control group among infants with complete growth data. The risk-difference estimate is -0.155, with a 95% confidence interval from -0.280 to -0.030, and the unadjusted p-value is 0.018. Those statistics describe the observed comparison and its uncertainty under the relevant calculation; they do not by themselves establish a causal mechanism or explain how the group contrast arose.

The result applies to the registered threshold and the birth-to-6-month interval. It does not describe every feature of infant growth, later outcomes, or all elements of the study’s broader aim to influence health trajectories and services. Nor does it directly answer whether maternal or paternal outcomes changed, or whether any secondary outcome explains the primary result. The secondary estimates are separate, unadjusted comparisons with their own uncertainty.

Randomized assignment is a useful design feature for comparing groups, but the registry does not report enough detail to assess allocation procedures, adherence, masking implementation, or the handling of missing outcomes. The primary analysis uses complete growth data, and the record does not report missing-data sensitivity analyses. Consequently, the posted comparison should be understood in relation to the participants who contributed complete primary measurements, rather than assumed to represent every enrolled or randomized family equally.

The results do not establish that the intervention would produce the same pattern in another setting or population. The registry record does not report detailed intervention content or enough implementation information to assess what parts of the program were delivered. The result also does not show that the intervention caused an individual infant’s growth trajectory, or predict any individual outcome. It is a group-level statistical comparison, not medical advice.

17. Why This Trial Matters Statistically

This trial is statistically informative because it combines randomized group assignment with an outcome defined at the infant level and reported as counts in each group. That makes the primary comparison interpretable on several scales: an absolute risk difference, a relative risk, and an odds ratio. Seeing how the same data are expressed on these scales helps readers distinguish absolute from relative comparisons and avoid treating different measures as independent findings.

The complete-data outcome definition also illustrates a key issue in trial interpretation. Enrollment and the population contributing to an outcome are not necessarily the same. The primary comparison includes infants with growth data at both specified ages, while the registry reports a larger overall enrollment figure. Without details on missingness and participant flow, readers cannot determine how fully the primary analysis represents the trial population. This is an important uncertainty, not merely a technical footnote.

The record also offers a useful example of the difference between observed results and design planning. The sample-size illustrations use the observed effect under a stated set of assumptions, whereas the trial’s original sample-size justification is not reported. Planning figures can show how assumptions about target effect and power influence required enrollment, but they cannot be treated as evidence that a completed study had a particular power.

Finally, the registry lists many outcomes and posts several unadjusted secondary comparisons without reported analyses or a documented multiplicity approach. This makes it important to separate the primary result from exploratory or descriptive secondary information. The distinction helps readers assess how much weight to place on each finding without turning statistical summaries into broader claims than the record supports.

18. 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 trial are apparent from the registry record. The primary endpoint is available for infants with complete growth data at birth and 6-months, and the record does not describe the amount or pattern of missing growth data. This leaves uncertainty about how the complete-data population relates to all enrolled families and whether missingness could have influenced the group comparison.

The registry reports overall enrollment of 657, while the study summary says the study planned to enroll 250 father-mother dyads. It does not explain the difference. The primary outcome denominators are also smaller than the overall enrollment figure, but the record does not provide participant flow or reasons for non-inclusion in the primary analysis. These figures should not be reconciled by assumption.

Intervention and control descriptions are limited to their names and the statement that each was added to obstetric and pediatric standard of care. The registry does not report detailed program components, intervention exposure, adherence, or implementation fidelity. The single-masked classification is listed without stating who was masked. Randomization methods and allocation concealment are not described.

The record does not report a statistical analysis plan, the original sample-size justification, interim analyses, adjustment for multiple outcomes, detailed models, or missing-data sensitivity analyses. The primary p-value is unadjusted, and the posted secondary comparisons are also unadjusted. The registry reports no analyses for the secondary results. These gaps limit assessment of prespecification, analysis choices, and the strength of inferences across the full set of outcomes.

Finally, the primary endpoint uses a thresholded measure of weight-for-age z-score change over a specified early-life interval. It does not summarize the full distribution of growth changes or later outcomes. Interpretation should remain limited to that endpoint and the recorded analysis population.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: First Heroes: Engaging Fathers in the First 1000 Days — NCT04477577.
• Registry record last updated 2026-05-11; status last verified 2026-04.
• Results first posted 2026-05-11.
• 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.

22. Record Summary

First Heroes: Engaging Fathers in the First 1000 Days is a completed randomized, single-masked, parallel trial sponsored by Massachusetts General Hospital. The registry lists enrollment of 657 and records primary completion on 2023-11-30. Its study summary describes two groups receiving obstetric and pediatric standard of care with either the New Parent Engagement Intervention or Safety Control.

The primary endpoint is the number of infants meeting the rapid infant weight gain definition from birth to age 6 months, among those with complete growth data at both ages. The posted group counts are 12.0 of 79.0 and 27.0 of 88.0. The reported risk difference is -0.155, with a 95% confidence interval from -0.280 to -0.030, and the unadjusted p-value is 0.018.

Selected maternal secondary outcomes and safety figures are also posted. The registry record does not report the trial’s original statistical plan, sample-size justification, detailed intervention content, missing-data analyses, or multiplicity strategy. Those limits matter when interpreting the estimates and their scope.