This retrospective single-center observational cohort study evaluates live birth rates after the first embryo transfer following immune assessment in infertile women with documented uterine immune overactivation.

In routine clinical practice, glucocorticoids represent first-line therapy for immune overactivation. Some patients underwent glucocorticoid sensitivity testing prior to embryo transfer based solely on standard clinical practice and patient preference. In cases of demonstrated glucocorticoid resistance, alternative therapeutic strategies were implemented according to usual care.

The study analyzes clinical data collected between September 2020 and November 2025 to assess the association between prior glucocorticoid sensitivity testing and live birth rate after the first fresh or frozen blastocyst transfer performed following immune evaluation.

No treatment allocation was determined by a study protocol.

This retrospective single-center cohort study was conducted at Hôpital Pierre Rouquès - Les Bluets (Paris, France) and includes infertile women aged 40 years or younger undergoing in vitro fertilization (IVF) between September 2020 and November 2025.

All included patients had documented uterine immune overactivation identified through routine immune assessment prior to embryo transfer. In standard clinical practice at our center, glucocorticoids represent first-line therapy for immune overactivation.

Some patients underwent glucocorticoid sensitivity testing prior to embryo transfer, based solely on routine clinical practice and patient preference. In cases of demonstrated glucocorticoid resistance, alternative therapeutic strategies were implemented according to standard care.

The study compares live birth rates following the first fresh or frozen blastocyst transfer performed after immune evaluation in patients managed with or without prior glucocorticoid sensitivity testing.

This study is purely observational and retrospective. No treatment allocation or testing decision was determined by a study protocol.

Inclusion Criteria:

• Infertile patients undergoing IVF with planned fresh or frozen embryo transfer
• Age ≤ 40 years at the time of the transfer
• Documented uterine immune over-activation
• Treatment with glucocorticoids in routine clinical practice, with or without prior glucocorticoid sensitivity testing
• Fresh or frozen blastocyst transfer performed within 9 months following immune assessment at Hôpital des Bluets

Exclusion Criteria:

• • Age > 40 years

  • No available uterine immune profile
  • Normal immune profile or immune underactivation
  • Management exclusively with alternative therapeutic strategies (e.g., low molecular weight heparin [LMWH], intralipid therapy) or combination therapies (e.g., LMWH + glucocorticoids or intralipid + glucocorticoids)
  • Embryo transfer performed more than 9 months after immune assessment
  • Cleavage-stage embryo transfer
  • Embryo transfer performed in another center
  • Oocyte donation IVF cycles

The study population consists of infertile women aged 40 years or younger undergoing in vitro fertilization (IVF) with a planned fresh or frozen blastocyst transfer at Hôpital Pierre Rouquès - Les Bluets (Paris, France). All patients had documented uterine immune overactivation identified through routine immune assessment prior to embryo transfer. Patients were managed according to standard clinical practice, with first-line glucocorticoid therapy, with or without prior glucocorticoid sensitivity testing.