Background  The management and treatment of patients with poor ovarian response (POR) is still a controversial issue in assisted reproductive technology. Many ovarian stimulation protocols have been applied to patients with POR, however, a consensus upon which is the most beneficial has not been reached yet.

  Objective  To compare the clinical outcomes of three different stimulation protocols (CC + HMG protocol, CC + HMG + antagonist protocol and FSH + antagonist protocol), and explore a better protocol plan for patients with POR.

  Methods  A retrospective analysis was performed in infertile women with poor ovarian response after in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) in the First Medical Center of Chinese PLA General Hospital from January 2017 to December 2019. Data of 279 stimulation cycles were analyzed. The patients were divided into CC + HMG protocol group (group A), CC + HMG + antagonist protocol group (group B) and FSH + antagonist group (group C). The following data, including the dosage and duration of gonadotropin (Gn) use, level of LH on trigger day, rate of premature LH surge, cycle cancellation rate, number of oocytes obtained, number of cleavage embryos and number of high-quality embryos and clinical pregnancy rate were compared between the three groups.

  Results  There was no significant difference in age, duration of infertility, bFSH, bLH, AFC, BMI among the three groups (P＞0.05). Gn dosage was highest in group C (1842.47 ± 538.95) IU, followed by the group B (551.79 ± 182.85) IU, and lowest in the group A (450.00 ± 151.82) IU; Gn duration in the group C (8.51 ± 1.59) d was longest, followed by the group B (7.08 ± 2.09) d, and then the group A (6.00 ± 2.02) d; Level of LH on trigger day was highest in the group A (10.41 ± 5.29) U/L, followed by the group B (6.53 ± 3.31) U/L, and lowest in the group C (3.90 ± 3.01) U/L; Rate of premature LH surge was highest in the group A (33.3%), followed by the group B (14.3%), and lowest in the group C (2.4%); The differences in these variables were significant between the three groups (all P＜0.05). Rate of cycle cancellation in the group A was 23.8%, which was significantly higher than that in the group B (0) and C (0) (P=0.000). Number of oocytes obtained in the group C (2.58 ± 1.49) was significant greater than that in the group B (2.01 ± 1.32) and the group A (1.94 ± 0.98) (P＜0.05). But the number of cleavage embryos and high-quality embryos were similar in the three groups (P＞0.05). Clinical pregnancy rate in the group A (13.0%) was lower than that in the group B (24.5%) and C (28.8%), without statistically significant difference (P＞0.05).

  Conclusion  For infertile women with POR, the CC + HMG + antagonist protocol is better than CC + HMG protocol, as the former protocol has lower cycle cancellation rate and higher clinical pregnancy rate. Compared with FSH + antagonist protocol, the CC + HMG + antagonist protocol almost has the same clinical pregnancy rate but lower dosage of gonadotropin and shorter duration. Furthermore, patients used CC + HMG + antagonist protocol usually cost less and repeat more ovarian stimulation cycles during the same period. In conclusion, the CC + HMG + antagonist protocol is recommended for infertile patients with POR.