The Importance of Mid-Follicular Phase Luteinizing Hormone Rise in GnRH Antagonist-Based Ovarian Stimulation for IVF

<b><i>Introduction:</i></b> Previous publications examined the endocrinology of follicular stimulation, focusing on luteinizing hormone (LH) levels changes. In selected, good prognosis IVF patients, a sharp drop in LH serum level was demonstrated between cycle days 2 and 6. <b><i>Objective:</i></b> The purpose of this study was to examine if this finding holds true for unselected patients. <b><i>Methods:</i></b> We retrospectively included 165 consecutive patients treated with a GnRH antagonist-based ovarian stimulation protocol during the year 2015. <b><i>Results and Conclusions:</i></b> In 33% of the patients an increase in LH, rather than the expected decrease, was demonstrated after 5 stimulation days. There was no difference in pregnancy outcome. Our results suggest that an increase in LH levels during ovarian stimulation occurs mainly in “high responders”, or “low responders”. LH rise in mid follicular phase may result in a sharp LH drop once a GnRH antagonist is given, and the possible need for LH supplementation.