INTRODUCTION

The first in vitro fertilization (IVF) baby was born after a natural IVF cycle. In the early days of IVF, clomiphene citrate was used for ovarian stimulation, and later urinary gonadotrophins were used for controlled ovarian hyperstimulation. A decade later, recombinant follicle-stimulating harmone (FSH) was produced (2), and since then, there is an ongoing debate between using urinary versus recombinant gonadotrophins (3).

From the mid-1980s, ovarian stimulation protocols combined the use of gonadotrophins with gonadotrophin-releasing hormone agonist (GnRHa) in order to increase oocyte number and to avoid premature luteinizing hormone (LH) surge (4). In the twenty-first century, GnRH antagonist became available as an alternative to GnRHa (5).

With the recent interest in evidence-based medicine, it would be logical to search for the optimum protocol of ovarian stimulation, decreasing rate of OHSS, and yet achieving at least the same success rate to provide our patients with the best possible care. Randomized controlled trials and systematic reviews are considered the source of the top-quality evidence. One big advantage of systematic reviews is pooling the results of studies with similar methodology and addressing the same topic, hence achieving large sample size and tightening the confidence in the results obtained (Al-Inany et al., 2003).

COH PROTOCOLS: WHAT CHALLENGED THE GOLDEN RULE?

Pharmaceutical preparations of human gonadotrophins play an important role to achieve multifollicular development (6).