Embryos derived from single pronucleus are suitable for preimplantation genetic testing

Objective: To study and compare the preimplantation genetic testing for monogenic disorders (PGT-M) results, and to evaluate the treatment cycle outcomes of embryos derived from a single pronucleus (1PN) vs. two pronuclei (2PN). Design: A retrospective cohort study from January 2018 to December 2022 involving in vitro fertilization (IVF)-PGT-M treatment cycles. Setting: Single, academically affiliated fertility center. Patients: A total of 244 patients underwent 351 IVF-PGT-M treatment cycles. Intervention: Embryo biopsy with molecular testing for a monogenic disorder. Main Outcome Measures: The molecular diagnosis results and clinical outcomes after the transfer of embryos derived from 1PN and 2PN in IVF-PGT-M treatment cycles. Results: Embryos derived from 1PN have a significantly low developmental potential with a lower rate of embryos that underwent biopsy compared with 2PN-derived embryos; 1PN-derived embryos demonstrated a significantly lower number of blastocysts (24% vs. 37.9%) and top-quality blastocysts (22.3% vs. 48.1%) compared with 2PN-derived embryos. Lower successfully completed and unaffected PGT-M results were achieved in 1PN compared with 2PN-derived embryos (47.1% vs. 65.5% and 18.7% vs. 31.6%, respectively), with significantly higher abnormal molecular results (39.6% vs. 22.7%). The embryo transfer of 24 1PN-derived embryos with no affected genetic disorder resulted in 5 (20.8%) clinical pregnancies and 4 (16.7%) live births (LBs). Conclusions: Within the limits of fewer embryos derived from 1PN that yielded unaffected embryos suitable for transfer, the clinical pregnancy and LB rate of 1PN embryos undergoing PGT-M are reassuring. We, therefore, suggest applying PGT-M to embryos derived from 1PN embryos to improve the cumulative clinical pregnancy and LB rates.