Frozen Embryo Transfer

This randomized clinical trial aims to assess the comparative effectiveness of two distinct endometrial preparation protocols for frozen embryo transfer (FET) among women with adenomyosis undergoing IVF/ICSI. Specifically, it seeks to address the following key questions: 1. Does the protocol involving the combination of GnRH agonist and letrozole for down regulation with exogenous steroids (GnRHa+AI - AC) result in a higher live birth rate compared to the use of exogenous steroids alone (AC) in women with adenomyosis undergoing frozen embryo transfer? 2. What are the common side effects of the GnRHa+AI - AC regimen? Eligible participants will undergo screening before endometrial preparation for FET, following which they will be randomly assigned to one of two groups: GnRHa+AI - AC or AC. In the GnRHa+AI - AC group, participants will be pre-treated with GnRH agonist and letrozole two months before endometrial preparation. After this period, participants will return for endometrial preparation, and any side effects resulting from the down regulation will be evaluated. In contrast, the AC group will receive standard treatment.

To investigate the levels of Relaxin in different types of endometrial preparation for a frozen embryo transfer cycle. Up to now it is unclear, whether ovulation with a functional corpus luteum (CL) will be present in a natural proliferative phase (NPP) endometrial preparation approach.

This study will assess the convenience of the natural proliferative phase frozen embryo transfer (NPP-FET) in terms of number of number of appointments needed before cycle scheduling.

Lipiodol® flushing is an effective fertility treatment for women with unexplained infertility. It is speculated that the treatment effect could work through a direct effect of Lipiodol® on the endometrium. Given this direct effect on the endometrium, it is further hypothesized that Lipiodol® uterine treatment prior to In Vitro Fertilization (IVF)/ Intracytoplasmic Sperm Injection (ICSI) may also improve pregnancy rates. However, the effectiveness of Lipiodol® as an adjunct to IVF/ICSI treatment has not previously been examined in a well-powered and properly conducted randomised clinical trial.