ASA 81 mg vs 162 mg During Frozen Embryo Transfer (FET)

Retrospective Study to Assess if Aspirin 162 mg is Better Than 81 mg for Embryo Transfer Outcomes

The use of low dose aspirin is recommended for high risk patients to reduce the risk of pre-eclampsia, placental abruption and antepartum hemorrhage. Recent studies have shown that in a specific population, the use of low dose aspirin might reduce the risk of preterm birth in pregnant women with singleton pregnancy. In June 2022, clinique ovo started implementing the use of Aspirin 162 mg instead of 81 mg in the frozen embryo transfer cycles based on recent study outcomes. The use of Aspirin 162 mg might have additional benefits on the embryo transfer outcomes by decreasing the miscarriage. Moreover this can be continued until late in pregnancy without adverse effects.

Study Overview

• Status: Completed
• Conditions: Fertility Disorders
• Intervention / Treatment: Other: Frozen embryo transfer

• Study Type: Observational
• Enrollment (Actual): 1207

Contacts and Locations

Study Locations

• Canada
  • Quebec
    • Montreal, Quebec, Canada, H4P 2S4
      • Clinique ovo

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult
• Accepts Healthy Volunteers: N/A

• Sampling Method: Probability Sample

Study Population

FET Data spreadsheet from January 2022 to December 2022

Description

Inclusion Criteria:

• Women taking aspirin 81 mg or 162 mg prior to an autologous embryo transfer
• Age < 40 years old
• Embryo transfer cycle done at clinique ovo

Exclusion Criteria:

• Egg or embryo recipient
• History of recurrent miscarriages, defined as ≥ 3 consecutive losses
• Patients that needed Viagra, PRP or other modalities to improve their endometrial thickness
• Uterine factor infertility
• Abnormal hormonal profiles
• Stimulated embryo transfer cycles
• History of recurrent implantation failure defined as failed ≥ 2 euploid embryos transfer or ≥ 3 blastocysts

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Aspirin 81 mg for Frozen Embryo Transfer (FET); Subjects were prescribed Aspirin 81 mg to be started on the third day of their menstrual cycle in preparation for their FET.	Other: Frozen embryo transfer; A frozen embryo transfer involves thawing a fertilized embryo and transferring it in the uterus in order to obtain a pregnancy
Aspirin 162 mg for Frozen Embryo Transfer (FET); Subjects were prescribed Aspirin 162 mg to be started on the third day of their menstrual cycle in preparation for their FET	Other: Frozen embryo transfer; A frozen embryo transfer involves thawing a fertilized embryo and transferring it in the uterus in order to obtain a pregnancy

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Compare clinical pregnancy rate between patients prescribed Aspirin 81 mg vs Aspirin 162 mg	clinical pregnancy is the presence of fetal heartbeat at the viability ultrasound	Time Frame: 6 to 8 weeks after Frozen Embryo Transfer

Collaborators and Investigators

• Sponsor: Clinique Ovo
• Investigators: Principal Investigator: Wael Jamal, MD, Clinique ovo

Study record dates

Study Major Dates

• Study Start (Actual): November 1, 2023
• Primary Completion (Actual): August 30, 2024
• Study Completion (Actual): September 18, 2024

Study Registration Dates

• First Submitted: November 7, 2023
• First Submitted That Met QC Criteria: November 7, 2023
• First Posted (Actual): November 13, 2023

Study Record Updates

• Last Update Posted (Estimated): December 9, 2025
• Last Update Submitted That Met QC Criteria: December 3, 2025
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Other Study ID Numbers: 3384

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No