Background: For infertile women aged over 37 years, failure of the zona pellucida to rupture is believed to be associated with a decreased implantation rate in in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). It has been suggested that assisted hatching of embryos will increase the pregnancy rate with IVF by means of mechanically facilitating the hatching process.
Methods: One hundred twenty cycles of IVF/ICSI in females aged over 37 years were analyzed. Women included in this study were allocated into 2 groups. In group I, embryos were cultured and transferred without laser-assisted hatching (LAH), whereas embryos of group II were examined and treated with LAH just before being transferred. Laser manipulations were performed using a 1.48-microm (infrared) diode laser (Fertilase). The laser was aimed at the zona to create openings of about 20 microm in diameter.
Results: The mean ages of women in groups I and II were 38.8 +/- 1.8 and 39.5 +/- 1.6 years, respectively (p = 0.17). The number of retrieved oocytes, endometrial thickness, and number and quality of transferred embryos did not significantly differ between the 2 groups. Rates of implantation (7.3% and 6.7%, respectively, p = 0.89), pregnancy (16.3% and 17.5%, respectively, p = 0.86), and early pregnancy loss did not differ between the 2 groups.
Conclusion: Our data failed to demonstrate any benefit of LAH in improving implantation or pregnancy rates in women of advanced age, suggesting that factors other than laser drilling of the zona should be considered.