Calcium ionophore improves embryonic development and pregnancy outcomes in patients with previous developmental problems in ICSI cycles

Calcium (Ca2+) ionophores are now mainly considered as efficient treatments for fertilization failure. Recently, its application for rescuing poor embryo development was proposed but still non-routine. This study aimed to explore whether Ca2+ ionophore improves embryo development and pregnancy outcomes in patients with poor embryo development in previous intracytoplasmic sperm injection (ICSI) cycles.This study included 97 patients undergoing assisted oocyte activation (AOA) with Ca2+ ionophore (calcimycin, A23187) treatment. Preimplantation embryonic development and clinical outcomes were compared between ICSI-AOA cycles (AOA group) and previous ICSI cycles of the same patients in which poor embryo developmental potential was present (non-AOA group). Subgroups stratified by maternal age (< 35, 35-40, ≥ 40 years, respectively) were analyzed separately.A total of 642 MII oocytes were collected in AOA group, and 689 in non-AOA group. Significantly higher day 3 good quality embryo rate (P = 0.034), good quality blastocyst formation rate (P < 0.001), and utilization rate (P < 0.001) were seen in AOA group. Similar results were seen in each subgroup. For pregnancy outcomes, there were significant differences in clinical pregnancy rate (P = 0.039) and live birth rate (P = 0.045) in total group. In subgroup aged < 35 years, biochemical (P = 0.038), clinical (P = 0.041), and ongoing pregnancy rate (P = 0.037) in AOA group were significantly higher than that in non-AOA group. No significant improvement for clinical outcomes for subgroups aged 35-40 and aged ≥40.The study suggests that calcimycin could improve preimplantation development and pregnancy outcomes in patients aged < 35 years with embryo developmental problems in previous ICSI cycles.