Development and frozen-thawed transfer of non-pronuclear zyg
The study explores the development and pregnancy potential of non-pronuclear (0PN) zygote-derived embryos in conventional in vitro fertilization (IVF) cycles.

Embryonic development in 1039 oocyte retrieval cycles and clinical outcomes of 659 frozen-thawed blastocyst transfer cycles were retrospectively studied.

- The developmental potential of embryos with different blastomere numbers on day 3 was inconsistent in 0PN and 2PN groups.

- For 0PN-derived embryos, the blastocyst rate of fast-developing embryos was similar to that of intermediately developing embryos, but the good quality blastocyst rate of the former was significantly higher than that of the later.

- In the 2PN group, intermediately developing embryos had the highest blastocyst rate and good quality blastocyst rate.

- Comparison of frozen-thawed transfer was carried out between 0PN- and 2PN-derived blastocysts. For both single (SBT) and double blastocyst transfer (DBT) groups, no statistical differences existed between 0PN- and 2PN-derived blastocysts in clinical pregnancy rates, implantation rates and live birth rates.

The developmental characteristic of 0PN-derived embryos was different from that of 2PN-derived embryos in IVF cycles. 0PN-derived blastocysts could obtain acceptable clinical pregnancy and live birth.

European Journal of Obstetrics & Gynecology and Reproductive Biology