In vitro fertilization in the natural cycle.
In vitro fertilization in the natural or spontaneous reproductive cycle was first described by Edwards and his colleagues in 1980 following the birth of their first natural cycle IVF baby 2 years earlier. Many groups attempted to follow their lead but it was almost ten years later that the next publication of success appeared (Foulot et al, 1989). The concept of IVF in the natural cycle is particularly attractive and so in 1987 our group also started evaluating the technique. Initial success in the patients with tubal lesions was not translated to patients with other infertility indications. Unfortunately the technique as initially developed was relatively inefficient with significant procedural losses at each stage. Over the succeeding four years a number of changes have been introduced and the efficiency considerably improved. Although these changes have improved take-home baby rates, overall pregnancy rates per embryo have not altered and are still lower than spontaneous in vivo pregnancy rates. It is likely that in the future, with current developments in culture techniques and greater understanding of gamete biology, this situation will change significantly.