A Non-Inferiority Study on Endometrial Preparation Prior to FET-Letrozole Versus Hormone Replacement Therapy

To compare the efficacy of letrozole-stimulated cycles to the more conventional artificial programmed cycles, in endometrial preparation for frozen embryo transfer (FET), in terms of endometrial parameters, reproductive outcomes, other practical parameters like number of visits to the clinic, cost involved, and patient satisfaction.

This prospective cohort study was conducted at Rao Hospital for a period of 11 months. The study included a total of 152 cycles of frozen embryo transfers. Fifty-five women selected for Group A underwent letrozole FET. Ninety-seven women selected for Group B had an artificial hormone replacement for endometrial preparation, prior to FET. All patients were followed-up with serial ultrasounds and FET done when endometrium reached desired state.

The endometrial thickness was comparable in both the groups, and on 3D endostudy, the flow index was non-significantly higher in the hormone replacement therapy (HRT) group. Other variables like vascularity index (VI), volume, and vascularization flow index (VFI) were similar in the two groups. The clinical pregnancy rate was higher in the letrozole group than the artificial cycle group, though not with significant difference. The live birth rate was higher in the patients on HRT than letrozole. The miscarriage rates were comparable in both groups. The medical comorbidities were significantly higher in the HRT cycles.

Letrozole FET could be a better alternative to the conventional HRT cycles, in selected population of patients, in terms of reproductive outcomes and patient satisfaction.