Reply: Impact of letrozole-associated controlled ovarian hyperstimulation on ART outcomes and endocrinological parameters.

Abstract

Sir, We welcome the interest in our work from Dr Goldrat et al. (2022) and find their comments important for the further development of the use of letrozole (LZ) co-treatment during ovarian stimulation in normo-responder women. We have the following comments. In our recently published paper (Poulsen et al., 2022), the endocrine and paracrine effects of LZ co-treatment during the entire follicular phase of ovarian stimulation in normo-responders were described. We found marked differences in circulating hormone parameters between randomization groups as well as an increased follicular size on oocyte pick up day in the LZ co-treated women, which may be explained by the altered endocrine milieu. Previously, we have demonstrated increased concentrations of androgens in follicular fluid of LZ co-treated women at oocyte pick up, even when the LZ co-treatment was confined to the early follicular phase (Lossl et al., 2006). In our recent study, we found no differences in numbers of aspirated oocytes nor pregnancy rates but, as we pointed out, the study was not powered to find differences in these parameters. However, previous larger randomized trials in normo-responder women have failed to demonstrate an increased pregnancy rate (reviewed in Bülow et al., 2022), while some studies do report an increased oocyte yield in the LZ co-treated women (Ecemis et al. 2016; Haas et al., 2017).