Ovarian stimulation protocols in assisted reproductive technology: an update

Controlled ovarian stimulation (COS) with gonadotropins to produce multiple follicular development and high-quality oocytes is the cornerstone of assisted reproductive technology. Today, recombinant human follicle-stimulating hormone (r-hFSH) is widely used for COS. A long-acting r-hFSH and a combination of r-hFSH and recombinant human luteinizing hormone have recently become available. Formulations of purified urinary FSH with or without luteinizing hormone activity (provided by human chorionic gonadotropin) are also available. COS protocols can now be individualized to optimize efficacy and safety - defined as singleton pregnancies with a low incidence of ovarian hyperstimulation syndrome. This is facilitated by an estimation of ovarian response using the antral follicle count and/or serum anti-Mullerian hormone levels; anti-Mullerian hormone is viewed as the most reliable single marker. However, an efficient management strategy for poor responders to COS is still required. Developments in biomarkers and other techniques for accurate identification of viable oocytes and embryos and optimal uterine receptivity are expected.