Intervention Arm vs Placebo Arm: Incidence of Preterm Birth

Calculated by ConductScience from the counts the trial posted to ClinicalTrials.gov.

Measures 6

Calculated by ConductScience from the counts the trial posted to ClinicalTrials.gov.

Measure	Value	95% interval, lower	95% interval, upper	Method	Source
Risk in group 1	0.116	0.108	0.124	wilson	ClinicalTrials.gov
Risk in group 2	0.131	0.122	0.14	wilson	ClinicalTrials.gov
Risk difference, group 1 minus group 2	-0.0152	-0.0272	-0.00325	newcombe hybrid score	ClinicalTrials.gov
Risk ratio, group 1 over group 2	0.883	0.801	0.974	log	ClinicalTrials.gov
Odds ratio, group 1 over group 2	0.868	0.777	0.97	log	ClinicalTrials.gov
Number needed to treat, for one fewer participant with the outcome on Intervention Arm than on Placebo Arm	65.6	36.7	308	from the risk difference interval	ClinicalTrials.gov

Groups 2

Group 2 names the comparator: placebo.

Group	Title	Description	With the outcome	Analysed	ClinicalTrials.gov code	Source
Group 1	Intervention Arm	Daily administration of low dose (81 mg) aspirin \[also known as acetylsalicylic acid (ASA\], initiated between 6 0/7 weeks and 13 6/7 weeks GA and continued to 36 0/7 weeks GA.	668	5,780	OG000	ClinicalTrials.gov
Group 2	Placebo Arm	Identical appearing placebo beginning between 6 0/7 weeks and 13 6/7 weeks GA and continuing until 36 0/7 weeks GA or delivery.	754	5,764	OG001	ClinicalTrials.gov

Outcome 5

Field	Value	Source
Type	PRIMARY	ClinicalTrials.gov
Title	Incidence of Preterm Birth	ClinicalTrials.gov
Description	The primary outcome of this study is incidence of preterm birth, which will be defined as delivery at or after 20 0/7 weeks and prior to 37 0/7 weeks. This will be determined based on actual date of delivery in comparison to the projected estimated due date (EDD), independent of whether or not the preterm delivery is indicated or spontaneous.	ClinicalTrials.gov
Time frame	At delivery	ClinicalTrials.gov
Population	Modified ITT; numbers reported reflect available data and therefore do not always reflect the total population defined in the mITT	ClinicalTrials.gov

Trial 8

Field	Value	Source
Title	Aspirin Supplementation for Pregnancy Indicated Risk Reduction In Nulliparas (ASPIRIN)	ClinicalTrials.gov
NCT number	NCT02409680	ClinicalTrials.gov
Phases	NA	ClinicalTrials.gov
Conditions	Premature Birth	ClinicalTrials.gov
Interventions	Low dose aspirin, Placebo	ClinicalTrials.gov
Lead sponsor	NICHD Global Network for Women's and Children's Health	ClinicalTrials.gov
Results first posted	2021-09-08	ClinicalTrials.gov
Results on ClinicalTrials.gov	https://clinicaltrials.gov/study/NCT02409680?tab=results	ClinicalTrials.gov

Source 4

Field	Value	Source
Release	trial-comparisons-2026-03-23-0.1.0	ClinicalTrials.gov
Release manifest SHA-256	f66225897fbf258b57ea10bdacfd0347d3cdfda93f7f5685234b7e06ea36fa57	ClinicalTrials.gov
AACT copy	2026-03-23	ClinicalTrials.gov
Tables read	outcome_counts.parquet, outcome_measurements.parquet, outcomes.parquet, reported_event_totals.parquet, reported_events.parquet, result_groups.parquet, studies.parquet, ctgov_trial.parquet	ClinicalTrials.gov

The same record as JSON

Release trial-comparisons-2026-03-23-0.1.0

ClinicalTrials.gov's posted results, through CTTI's AACT: ClinicalTrials.gov data via Aggregate Analysis of ClinicalTrials.gov (AACT), CTTI. CTTI makes its materials freely available and requests acknowledgement. https://aact.ctti-clinicaltrials.org/documentation/299 ClinicalTrials.gov's data carry an international copyright outside the United States: https://clinicaltrials.gov/about-site/terms-conditions. The measures are ConductScience's calculation from them.

ClinicalTrials.gov: none stated ClinicalTrials.gov's data carry an international copyright outside the United States: https://clinicaltrials.gov/about-site/terms-conditions. The measures are ConductScience's calculation from them.