Combination of Continuous Use of Oral Clomiphene Citrate with Injectable Gonadotropins for Ovarian Stimulation: A Single-Center Study

Abstract

Objective: This retrospective observational study evaluated the efficacy and safety of an ovarian stimulation protocol for embryo banking that involves continuous administration of clomiphene citrate (CC) in combination with gonadotropins, without the use of GnRH antagonists. Methods: Conducted at the Serum IVF Clinic in Athens, Greece, the study included 250 women aged 25–45 who underwent IVF for embryo banking. The protocol involved administering 150 mg of CC daily from day 2 of the menstrual cycle until the day before hCG trigger, alongside 150 IU/day of Meriofert. Outcomes assessed included oocyte yield, fertilization rates, incidence of ovarian hyperstimulation syndrome (OHSS), and hormonal correlations. Comparative and regression analyses explored differences between age groups and predictors of success. Results: The protocol demonstrated a favorable safety profile with no cases of OHSS and yielded a mean of 10.25 oocytes per patient. Group analysis showed significantly more oocytes retrieved in women under 40 (mean: 12.5) versus those over 40 (mean: 8.43), while fertilization rates were paradoxically higher in the older cohort (59.16% vs. 30.68%, p < 0.0001). Regression models revealed basal FSH to be a significant inverse predictor of oocyte yield, but it was positively associated with fertilization rate. Continuous CC use effectively suppressed premature LH surges without compromising oocyte or embryo quality, allowing flexible and cost-effective stimulation with minimal monitoring. Conclusions: Continuous administration of clomiphene citrate in combination with gonadotropins presents a promising, antagonist-free ovarian stimulation protocol for embryo banking. The approach is economically efficient, reduces monitoring requirements, and maintains safety and effectiveness and is particularly notable in women over 40. Further studies are warranted to validate these findings and refine protocol mechanisms.