Successful pregnancy following oocyte activation by strontium in normozoospermic patients of unexplained infertility with fertilisation failures during previous intracytoplasmic sperm injection treatment

Fertilisation failures occur in 2-3% of intracytoplasmic sperm injection (ICSI) cycles and are mostly caused by failure of oocyte activation. Assisted oocyte activation (AOA) may be an efficient treatment option to overcome oocyte activation failure. To evaluate the effectiveness of ICSI combined with AOA by strontium, six couples with complete fertilisation failure or low fertilisation rates (ranging from 0% to 16.7%; mean = 7.7%) in previous ICSI cycles were involved in the present study. In the latest ICSI cycles, AOA by strontium treatment was combined with ICSI to improve clinical outcomes. Fifty-two mature oocytes retrieved from six females were stimulated by strontium treatment after ICSI procedure, and 41 (78.8%) of them were successfully fertilised. The high-quality embryo rate was 41.5% (17/41) after culture for 5 days. Thirteen embryos were transferred (ranging from 2 to 3 per individual) resulting in three clinical pregnancies and three healthy babies were born. Furthermore, a pregnancy resulting in the birth of a healthy female infant was achieved following transfer of three frozen-thawed embryos. In conclusion, it appears that strontium treatment would be an effective method for AOA to improve fertilisation rates and embryo quality in cases with fertilisation failure after ICSI.