Day Two Post Retrieval 1,500 IUI hCG Bolus, Progesterone-Free Luteal Support Post GnRH Agonist Trigger

Small dose of hCG (1,500 IU) on the day of oocyte retrieval, followed by daily progesterone administration, is currently the preferred way to secure adequate luteal support following GnRH agonist trigger. The current study aims to evaluate if a bolus of 1,500 IU hCG, given two days after oocyte retrieval, is sufficient to sustain adequate luteal support without additional progesterone treatment.

From February 2015 to August 2016 we obtained 44 pregnancies following GnRHa trigger followed by day 2 hCG (1,500 IU) support-only (study group). Data from these 44 cycles were compared with the latest 44 pregnancies obtained following hCG (6,500 units) trigger followed by conventional progesterone luteal support. Serum β-hCG, P and E₂ levels were measured 14 days post oocyte retrieval. Pregnancy outcome was obtained from database or by a phone call.

Patients in the study group were younger and had more oocytes compared to the control group. Live birth rate and miscarriage rate were comparable between the two groups. Mean progesterone levels (14 days post oocyte retrieval) in the study (no progesterone supplementation) and control (progesterone supplemented) groups were 197nmol/l and 173nmol/l, respectively (NS). Mean E₂ levels (14 days post oocyte retrieval) in the study group was 6,937pmol/l, significantly higher (P<0.001) than in the control group (3,276pmol/l). Estradiol levels can reliably reflect luteal activity in both groups, as both groups were not supplemented with exogenous estradiol. Therefore, we conclude that deferred hCG bolus results in robust luteal phase, leaving any additional progesterone supplementation redundant.