Natural Versus Artificial Cycle for Frozen-Thawed Embryo Transfer

Frozen-thawed Embryo Transfer in a Natural Versus Artificial Cycle: a Randomized Clinical Trial

This study evaluates clinical pregnancy rates, obstetrical outcome parameters, costs and patient preferences in natural cycle versus artificial cycle frozen embryo transfers (FET).

Transfer of cryopreserved embryos can be performed in a natural cycle (NC-FET) or in an artificially prepared cycle (AC-FET). Both cycle regimens have their advantages and disadvantages. So far, most comparative studies have failed to identify the optimal protocol for FET. In this study patients undergoing FET will be randomized between an endometrial preparation by a natural cycle or by an artificial cycle (by oestradiol validate and micronized progesterone).

Inclusion Criteria:

• Women undergoing FET after a first, second or third fresh IVF/ICSI cycle
• Single embryo transfer (SET) or Double embryo transfer (DET)
• Female age between 18-45 year
• Women having a natural ovulatory cycle (24-35 days)
• Normal uterine cavity (fundal indentation at the cavity <10mm)
• Written informed consent

Exclusion Criteria:

• Use of donor gametes
• BMI > or equal to 35 kg / m2
• Any contra-indication to estrogen or progesterone supplementation (e.g. history of thrombosis, prior or current hormone-sensitive malignancy…)