Use of the egg-share model to investigate the paternal influence on fertilization and embryo development after in vitro fertilization and intracytoplasmic sperm injection.

OBJECTIVE

To investigate whether sperm from different males can influence fertilization and embryo development.

DESIGN

To use an egg-sharing model, in which the eggs from one woman are shared between herself and a recipient, and different spermatozoa are used to fertilize the eggs.

SETTING

Assisted Conception Unit, Birmingham Women's Hospital, Edgbaston, United Kingdom.

PATIENT(S): Infertile women undergoing egg sharing.

INTERVENTION(S): In vitro fertilization (IVF).

MAIN OUTCOME MEASURE(S): Fertilization rates and the mean day 2 or 3 embryo score (cell number X grade) were examined for egg-sharing pairs. A comparison was also made for pairs in which intracytoplasmic sperm injection (ICSI) and IVF was used as the insemination method. A paired samples t-test was used to compare the sharer and recipient results.

RESULT(S): Pregnancy rates did not differ between sharer and recipient couples. Interestingly, when comparing fertilization, there was a significant difference (P<.05) in favor of IVF over ICSI. When comparing embryo development between egg-sharing pairs, we found that approximately 30% of patients showed a difference in mean embryo score of >or= 5 in all embryo development and 14% in the quality of embryos available for transfer.

CONCLUSION(S): We showed that the egg-sharing model is a successful alternative for the treatment of women who required donated eggs. More important, the egg-sharing model shows that, in a certain percentage of couples, differences in early embryo development are paternally influenced.