Parental Balanced Translocation Carriers do not have Decreased Usable Blastulation Rates or Live Birth Rates Compared to Infertile Controls.

Objective: To determine if translocation carriers have a reduced number of usable blastocysts compared to infertile controls.

Design: Retrospective cohort study.

Subjects: All cycles of balanced translocation carriers undergoing IVF with preimplantation genetic testing (PGT-SR) for structural rearrangements at a single infertility center compared to an age-matched control cycles of infertile patients undergoing preimplantation genetic testing for aneuploidy (PGT-A) from January 2012-August 2022.

Exposure: Balanced translocation carriers.

Main outcome measures: Primary outcome measures were blastulation rate, usable blastulation rates and live birth rate. Secondary outcome measures were sustained implantation rate, fertilization rate, number of oocytes retrieved, number of metaphase II oocytes, total blastulation failure, number of 2 pronuclear embryos, and number of euploid embryos. Outcome measures were compared between male translocation carriers and controls, female translocation carriers and controls, and Robertsonian versus reciprocal translocation carriers.

Results: A total of 1,291 retrieval cycles from 993 patients were included, of which 255 patients were translocation carriers, while 738 were controls. Of those with translocations, 30 (11.5%) were Robertsonian and 231 (88.5%) were reciprocal carriers. There was a statistically significant difference in the blastulation rate between carriers and controls (59.5% versus 62.1%; p-value = 0.01). However, usable blastulation rates (47.2% versus 50.0%) were equivalent between groups. There were no differences in number of oocytes retrieved (18.5 versus 18.3), number of 2 pronuclear embryos (13.4 versus 12.5), sustained implantation rate (71.4% versus 75.1%) or live birth rate (63.0% versus 66.1%) between translocation carriers and controls. In both male and female translocation carriers versus controls, there were no differences in usable blastulation rates or live birth rates. When comparing Robertsonian with reciprocal translocation carriers, rates of blastulation, usable blastulation, sustained implantation, and live birth rate were equivalent.

Conclusion: Despite fewer euploid embryos, there were no differences in rates of usable blastulation or live birth rates in balanced translocation carriers, regardless of sex of affected partner or type of rearrangement, compared to controls. Routine karyotyping for blastulation failure may not be necessary based on these findings.