Fixed Versus Flexible Administration of the Antagonist

In the first study using GnRH-nt, the protocol included a fixed day of GnRH-nt administration. In the multiple-dose protocol, the antagonist

Multiple Dose Protocol Fixed Flexible
Figure 3 Gonadotropin-releasing hormone antagonist multiple- and single-dose protocols. Fixed day regimens. Abbreviations: FSH, follicle-stimulating hormone; hCG, human chorionic gonadotropin; hMG, human menopausal gonadotropin.

was started on day 6. In the single dose, the 3 mg administration of Cetror-elix was proposed on day 7. We proposed a more flexible approach by adapting the moment of antagonist administration to ovarian response (Fig. 3) (11). The antagonist could be administered when the leading follicle reached 14 mm and/or E2 reached 600pg/ml. The same approach was later proposed by Ludwig et al. (57) in the multiple-dose protocol (Fig. 3). Some authors have predicted a lower pregnancy rate when the flexible approach was proposed (58). Data remain controversial on this question. A recent meta-analysis did not find differences in the pregnancy rates between the flexible and fixed approaches (59).

A very early start of the antagonist, injected at the beginning of the stimulation, was proposed to reduce the LH levels at the beginning of the follicular phase. A prospective randomized study failed to demonstrate an advantage to this proposal (60). Moreover, a long period of injection of antagonist will really alter the main benefit of GnRH-nts.

Pregnancy Guide

Pregnancy Guide

A Beginner's Guide to Healthy Pregnancy. If you suspect, or know, that you are pregnant, we ho pe you have already visited your doctor. Presuming that you have confirmed your suspicions and that this is your first child, or that you wish to take better care of yourself d uring pregnancy than you did during your other pregnancies; you have come to the right place.

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