Mild Stimulation Protocols

Abstract

For many years the principle adopted was that the greater the number of eggs retrieved, the greater the chance of a pregnancy. To achieve this aim, large doses of gonadotrophins are used, most commonly with a long GnRH agonist protocol. This regimen is long, expensive, requiring high gonadotrophin dosage and frequent monitoring and pre-disposes to ovarian hyperstimulation syndrome or, at the least, abdominal discomfort. Unsurprisingly, it was the foresight of Robert Edwards that first called for the use of milder stimulation protocols and a more patient-friendly and safer approach in 1996. Since then much attention has been paid to this proposed change in thinking and many different protocols have been devised with the purpose of easing the patient burden with increased safety and efficiency. It is difficult to recommend a natural cycle as results are so poor especially in older patients. A so-called modified natural cycle employing mild stimulation and a GnRH antagonist has also produced disappointing results. The integration of clomifene and of letrozole into protocols has decreased gonadotrophin consumption but little else. The principles involved in the search for an efficient mild stimulation protocol are both honourable and logical. The balance between patient comfort and cost and live birth rates has to be taken into account. This very much depends on the characteristics of the subject. While few have faith in natural cycles, other protocols described here show some promise in good prognosis patients and more well-conducted trials should establish their worth.