Does Body Mass Index Affect Embryonic Mosaicism?

Abstract

Purpose: To examine the association between body mass index (BMI) and embryonic aneuploidy and mosaicism by trophectoderm biopsy with preimplantation genetic testing for aneuploidy (PGT-A). Methods: This was a retrospective cohort study evaluating 602 women who underwent undergoing their first fresh autologous stimulation cycles wherein all embryos were biopsied for PGT-A analysis from January 2016 through December 2019 in a multicenter academic fertility practice. Associations between BMI (kg/m2) and rates of euploidy (2016-2019) and mosaicism (2018-2019), including low-level (LL), high-level (HL), whole chromosome, and segmental mosaicism, were determined using forward stepwise multivariable Poisson regression.Results: 3,020 embryos from 602 cycles were available for analysis. Most patients were of normal weight (N=323) or overweight (N=143), or had class I obesity (N=80). Overall, 21% of patients in the cohort had obesity (BMI >30). There was no difference in overall euploid or mosaicism rate stratified by BMI. Compared with normal BMI, underweight (adjusted relative risk, aRR: 3.57 [1.31-9.78]), overweight (1.57 [1.01-2.43]), and obesity (1.55[1.03-2.35]) were each associated with significantly increased risks of LL mosaicism (6.6% vs. 20.8%, 10.0%, and 9.1%, respectively). Overweight BMI was associated with lower rates of HL (8.3% vs 3.7%, aRR: 0.39 [0.21-0.75]) and whole chromosome mosaicism (3.7% vs. 7.3%, aRR: 0.48 [0.26-0.91]) compared to normal BMI.Conclusions: While the overall rate of mosaicism was similar among BMI categories, both low and high BMI were associated with increased rates of LL mosaicism, and overweight was associated with decreased rates of HL and whole chromosome mosaicism compared to normal BMI.