Successful pregnancy after SrCl2 oocyte activation in couples with repeated low fertilization rates following calcium ionophore treatment

This report describes a successful pregnancy and delivery following oocyte activation with strontium chloride (SrCl2) in couples with repeated complete fertilization failure or low fertilization rates even after calcium ionophore treatment. Eight infertile couples who showed complete fertilization failure or low fertilization rates after conventional intracytoplasmic sperm injection (ICSI) and calcium ionophore treatment. When the results of fertilization were not satisfactory in the cycles, the oocytes were artificially activated by SrCl2 for the next attempts. Oocyte activation with SrCl2 significantly increased the fertilization rates, when compared with conventional ICSI or calcium ionophore treatment (61.7% vs. 20.0% or 25.3%, respectively). There was significant increase in the proportions of good-quality cleaved embryos (50.0% vs. 0% or 12.5%, respectively). The rate of surplus embryos that developed to blastocyst stage increased in SrCl2-treated oocytes, when compared with that in ICSI with or without calcium ionophore treatment (25.7% vs. 0% or 9.1%, respectively). Five successful pregnancies were attained after oocyte activation with SrCl2, of which eight healthy children were born. Physical and mental development of the children were normal from birth to 60 months. These results suggest that SrCl2 in treatment should be considered as an effective method for artificial oocyte activation (AOA) to improve fertilization rates and embryo quality in cases with complete fertilization failure or low fertilization rates after calcium ionophore treatment.