Impact of letrozole co-treatment during ovarian stimulation on oocyte yield, embryo development, and live birth rate in women with normal ovarian reserve: secondary outcomes from the RIOT trial.

Study Question: Does letrozole (LZ) co-treatment during ovarian stimulation with gonadotropins for in IVF impact follicle recruitment, oocyte number and quality, embryo quality, or live birth rate (LBR)?

Summary Answer: No impact of LZ was found in follicle recruitment, number of oocytes, quality of embryos, or LBR.

What Is Known Already: Multi-follicle stimulation for IVF produces supra-physiological oestradiol levels. LZ is an aromatase inhibitor that lowers serum oestradiol thus reducing negative feedback and increasing the endogenous gonadotropins in both the follicular and the luteal phases, effectively normalizing the endocrine milieu during IVF treatment.

Effects of letrozole cotreatment on endocrinology and follicle development in women undergoing ovarian stimulation in an antagonist protocol.

Study Question: What are the downstream endocrine and paracrine consequences of letrozole (LZ) cotreatment during ovarian stimulation and is follicle growth and recruitment affected?

Summary Answer: Letrozole cotreatment induces marked changes in both the follicular and luteal phase endocrinology causing potentiation of follicle diameter and an improved corpus luteum function without affecting the secondarily recruited follicle cohort.

What Is Known Already: Letrozole is a third-generation aromatase inhibitor that is well-established as an effective ovulatory agent, while its possible benefits in standard in vitro fertilization protocols are less thoroughly investigated.

Study Design, Size, Duration: This study included a double-blinded, placebo-controlled, randomized study with LZ or placebo intervention during ovarian stimulation for IVF treatment, an observational preceding baseline natural cycle and a succeeding follow-up visit.

Does adjuvant letrozole reduce uterine peristalsis prior to fresh embryo transfer?

Study Question: Does adjuvant letrozole in ovarian stimulation for IVF decrease the uterine peristalsis frequency (UPF) prior to fresh embryo transfer (ET)?

Summary Answer: Adjuvant letrozole in ovarian stimulation for IVF does not reduce the UPF significantly prior to fresh ET.

What Is Known Already: Throughout the cycle, uterine peristalsis aids spermatozoa transport to the fallopian tube and may affect implantation. At fresh ET, UPF is negatively correlated with implantation and clinical pregnancy rates and is believed to be modulated by oestradiol and progesterone.

Impact of letrozole co-treatment during ovarian stimulation with gonadotrophins for IVF: a multicentre, randomized, double-blinded placebo-controlled trial.

Study Question: Does letrozole co-treatment during ovarian stimulation with gonadotrophins for IVF reduce the proportion of women with premature progesterone levels above 1.5 ng/ml at the time of triggering final oocyte maturation?

Summary Answer: The proportion of women with premature progesterone above 1.5 ng/ml was not significantly affected by letrozole co-treatment.