Does the HCG trigger dose used for IVF impact luteal progesterone concentrations? a randomized controlled trial.

Research Question: Is there an association between the ovulation trigger dose of human chorionic gonadotrophin (HCG) and endogenous progesterone production during the luteal phase?

Design: This randomized controlled four-arm study, at the Fertility Clinic, Odense University Hospital, Denmark, included women undergoing gonadotrophin-releasing hormone (GnRH) antagonist IVF treatment with ≤11 follicles ≥12 mm. Group 1-3 were triggered with 5000 IU, 6500 IU or 10,000 IU HCG, respectively, receiving 17α-hydroxyprogesterone caproate intramuscularly for luteal-phase support (LPS) to measure endogenous progesterone production. Group 4 received 6500 IU HCG trigger and vaginal progesterone. During the study, the 5000 IU and 10,000 IU HCG groups were switched from urinary to recombinant HCG, as urinary HCG was removed from market. Eight blood samples were drawn during the luteal phase.

Results: Ninety-four participants completed the study. There was a significant positive association between the HCG trigger dose and the progesterone at 8 days (P < 0.001), 10 days (P < 0.001) and 14 days (P < 0.001) post-oocyte retrieval. Comparing the groups individually revealed a significant difference in progesterone concentration between low and high trigger doses at 4 days (P = 0.037) and 8 days (P = 0.007) post-oocyte retrieval and between all intervention groups at oocyte retrieval + 6 days: group 1 and 2 (P = 0.011), group 2 and 3 (P = 0.042) and group 1 and 3 (P < 0.001). Higher HCG trigger dose increased the progesterone from the individual follicle.

Conclusions: Increasing HCG trigger doses significantly increased endogenous progesterone concentration during the mid-late luteal phase.