Effect of laser zona pellucida opening on clinical outcome of assisted reproduction technology in patients with advanced female age, recurrent implantation failure, or frozen–thawed embryos

ObjectiveTo determine whether laser-assisted hatching can improve clinical outcome of assisted reproductive techniques in patients with advanced female age, with recurrent implantation failure, or who are using frozen–thawed embryos.DesignA prospective randomized study.SettingThe infertility and IVF unit at a research facility in Iran.Patient(s)Four hundred ten patients with advanced female age (≥37 y), 796 patients with recurrent implantation failure (for ≥2 cycles), and 180 patients with frozen–thawed embryos.Intervention(s)Patients were divided equally into test and control groups. On the day of embryo transfer, the zona pellucida of the selected embryos in the test group were opened about 40 μm by using an infrared optical laser system, whereas in the control group they were all intact.Main Outcome Measure(s)Clinical pregnancy rates and implantation rates.Result(s)In the patients with advanced female age or recurrent implantation failure, the clinical pregnancy and implantation rates were similar for the test and control groups. However, in the patients with frozen–thawed embryos, the rates were statistically significantly higher in the test group as compared with those of the control group (31.2% and 12.8% vs. 11.1% and 4.2%, respectively).Conclusion(s)The laser-assisted hatching improved the pregnancy and implantation rates in patients with frozen–thawed embryos but had no effect in patients with advanced female age or recurrent implantation failure.