Objective: To find if the zona thinning size (in length) of the embryos
transferred had any effects on the implantation and clinical pregnancy
rates. Design: A prospective randomized study Setting: Infertility and
Assisted Reproductive Techniques Centres. Material methods: Sixty
infertile women (≥38 years old) who underwent ICSI-ET procedures
and accepted to join this study were enrolled. Women were assigned as
one in 25 µm and the following in 50 µm zona thinning size
groups consecutively, according to the order of the transfers. Thirty
patients were assigned in each of the groups. Zona thinning procedure
without perforating the zona was performed on the embryos before
transfers, using a novel zona laser treatment system. Main outcome
measures: Implantation and clinical pregnancy rates. Results:
Implantation rates were 0.087±SD 0.160 and 0.099±SD 0.156
(p>0.05), and clinical pregnancy rates were 7/30 (23.3%) and 8/30
(26.7%) (p>0.05), in 25 and 50 μm zona thinning size groups,
respectively. Conclusion: Increasing the zona thinning length up to
twice the commonly used size did not have any significant effects on
the implantation and clinical pregnancy rates in women with advanced
age who underwent ICSI-ET treatment
