Early or late monitoring of stimulation of ovulation for in-vitro fertilization? A methodological discussion of a randomized study

: Two GnRH agonist long-stimulation protocols, in association with HMG, are compared on a random basis. Group A (n = 53) was monitored daily from the 6th day of stimulation, whereas monitoring in group B (n = 55) began on the 11th day of stimulation. There was no significant difference in the numbers of follicles which matured, the numbers of collected oocytes, the numbers of embryos obtained in vitro and the clinical pregnancy rate. But the power of such a study is very weak (6%). It would have been necessary to include greater than 1000 patients in each group to obtain a bioequivalence test. Such a study is unrealistic for a single centre and multicentric studies are very difficult to achieve because of practical difficulties. A pooled analysis is perhaps the methodological answer.