The role of the number of replaced embryos on intracytoplasmic sperm injection outcome in women over the age of 40

In order to examine if the transfer of more than three embryos has any beneficial effect on the outcome of intracytoplasmic sperm injection (ICSI) cycles in women aged >40 years, a retrospective analysis was made of all the ICSI cycles which were performed in this age group from 1 October 1991 to 31 December 1995. A total of 525 cycles was performed in 321 patients. In 413 cycles, at least one normally fertilized embryo was available for transfer. In 271 cycles, one to three embryos were replaced while in the remaining 142 cycles at least four embryos were replaced. There was no difference in implantation rate (number of gestational sacs/number of embryos transferred), after the transfer of one to three embryos (5.2%), compared with the transfer of at least four embryos (5.1%). The pregnancy rate/embryo transfer and the clinical pregnancy rate/embryo transfer were, however, higher when at least four embryos were replaced than was the case with one to three embryos (27.5 versus 11.8%, P < 0.0001 and 20.42 versus 9.96%, P < 0.005, respectively). There were no statistically significant differences in the delivery rates, multiple pregnancy rates or spontaneous abortion rates. The pregnancy rate and the clinical pregnancy rate after ICSI in women greater than or equal to 40 years of age are related to the number of embryos replaced.