The number of biopsied trophectoderm cells may affect pregnancy outcomes.

Objective: To study if the number of trophectoderm (TE) biopsied cells has an impact on implantation rates.

Design: A retrospective cohort study in a single-center study.

Setting: In vitro fertilization center.

Patients: Patients who underwent PGT-A from January 2013 to March 2016. In total, 482 vitrified/warmed single embryo transfers were included.

Interventions: None.

Main Outcome Measures: Clinical pregnancies rate, implantation rate.

Results: Overall, clinical pregnancies per embryo transfer were higher when a regular TE were biopsied compared to larger size biopsy cells (66% (175/267) vs 53% (115/215) (p < 0.005) respectively). Pregnancy rates were also analyzed according to embryo morphology at the moment of embryo biopsy, when a good-quality embryo was transferred the clinical outcome was 75% (81/108) in group 1 and 61% (60/99) in group 2 (p < 0.05). Data was also stratified by age in patients ≤ 35 years and > 35 years. The clinical pregnancy was 67% (51/76) in women ≤ 35 years and 65% (124/191) in women > 35 years when a regular size biopsy was performed. These results significantly reduced when a larger size biopsy was performed 54% (49/91) and 53% (66/124), respectively (p < 0.05). Further investigation indicated that miscarriage rate was similar between these groups (4% (7/182) in group 1 and 5% (6/121) in group 2).

Conclusions: These findings underscore that when a large amount of TE cells are biopsied, it may negatively affect implantation rates, but once implanted, the embryos have the same chance to miscarry or reach term.