Using progesterone to support pregnancy after frozen embryo transfer

Vaginal Progesterone as Luteal Support for Improvement of Live Birth in Frozen/Thawed In-vitro Fertilization Natural Cycles; a Multicenter, Open, Randomized Trial

PHASE4 · Vastra Gotaland Region · NCT04725864

This study is testing if using vaginal progesterone for either 3 or 7 weeks can help women have successful pregnancies after frozen embryo transfers compared to not using it at all.

Quick facts

PhasePHASE4
Study typeInterventional
Enrollment1800 (estimated)
Ages18 Years to 43 Years
SexFemale
SponsorVastra Gotaland Region (other gov)
Locations1 site (Gothenburg)
Trial IDNCT04725864 on ClinicalTrials.gov

What this trial studies

The ProFET study investigates whether vaginal progesterone support during the luteal phase is more effective than no support in achieving live births after frozen embryo transfers in natural cycles. This multicenter, open randomized controlled trial plans to enroll 1800 women undergoing this procedure. The study will compare the effectiveness of 3 weeks versus 7 weeks of progesterone treatment and assess various pregnancy outcomes, including rates of miscarriage and ectopic pregnancy. Additionally, the study will evaluate the impact of progesterone levels prior to embryo transfer on live birth rates.

Who should consider this trial

Good fit: Ideal candidates are women with a BMI between 18.5 and 35, regular menstrual cycles, and planned for a frozen embryo transfer with a blastocyst.

Not a fit: Patients with uterine malformations, serious diseases contraindicating ART or pregnancy, or those participating in other clinical studies may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could improve live birth rates for women undergoing frozen embryo transfers.

How similar studies have performed: Previous studies have shown mixed results regarding the efficacy of progesterone support in frozen embryo transfers, making this approach both relevant and necessary to explore further.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Planned for a FET-NC with a blastocyst
* BMI \>18.5 \<35
* Regular menstrual cycles 24-35 days
* Given informed consent
* Understand written and spoken Swedish, English or Arabic

Exclusion Criteria:

* Oocyte donor cycles, preimplantation genetic testing (PGT) cycles. Uterine malformation, submucous myoma and endometrial polyps.
* Hypersensitivity against study medication. Other contraindications according to www.fass.se
* Development of serious disease contraindicating ART or pregnancy.
* Participation or recent participation in a clinical study with an investigational product (past 30 days). Previous participation in this study.

Where this trial is running

Gothenburg

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.

View on ClinicalTrials.gov →

Conditions: Infertility, Embryo Transfer, progesterone, luteal phase support, frozen embryo transfer, natural cycles, live birth

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.