Impact of Sequential Double Embryo Transfer on Live Birth Rates: A Case-Control Study.

A CASE-CONTROL OBSERVATIONAL STUDY ON THE IMPACT OF A SEQUENTIAL DOUBLE EMBRYO TRANSFER POLICY ON LIVE BIRTH RATES IN COUPLES UNDERGOING ASSISTED REPRODUCTIVE TECHNOLOGY.

The main aim of this study is to evaluate the impact and identify potential indications for sequential double embryo transfer (SEQ-ET) in couples undergoing assisted reproductive technology (ART). The study will compare live birth rates (LBR) between patients receiving SEQ-ET and those receiving standard double embryo transfer (DET), while assessing safety outcomes and potential indications, including endometrial immune under-activation. Each SEQ-ET case will be matched with a DET control based on age, transfer attempt rank, and ART technique. We hypothesize that SEQ-ET may enhance implantation in couples with previous ART failures without increasing the risk of complications, potentially through localized maternal-endometrial immune communication initiated by the initially transferred cleavage-stage embryos.

Inclusion Criteria:

• Infertile patients undergoing IVF with planned SEQ-ET or DET.
• Age ≤ 42 years.

Exclusion Criteria:

• Age aged 43 years.
• Cycles in which only a single embryo was ultimately transferred and cycles in which no embryo transfer occurred.