Comparison of aneuploidy rate in spontaneous abortion chorionic villus between D6 and D5 thawed-frozen blastocyst transfer

Abstract

Abstract Background To compare the aneuploidy rate in spontaneous abortion chorionic villus (SA-CV) after D5 and D6 thawed-frozen blastocyst transfer(TBT). Methods This retrospective cohort study recruited 522 patients with early spontaneous abortion from March 2012 to January 2020 in the our center. The aneuploidy rate of SA-CV was compared according to the blastocyst development stage: D5 group (n = 398) and D6 group (n = 124). Results Patients’ characteristics, including age, body mass index, follicle-stimulating hormone, fertilization methods, and gestational age when miscarriage, did not differ between the two groups (all P > 0.05). Although the mean number of embryos was significantly higher in D6 than in the D5 group (P < 0.001), the mean number of top-quality embryos was similar (P = 0.773). In the D5 group, 46.5% of SA-CV showed aneuploidy, which was comparable to 41.1% in the D6 group (P = 0.296). After further grouping according to age (> 35 years or ≤ 35 years), the difference between the D5 and D6 groups remained not statistically significant (P = 0.247 and P = 0.690). Multivariate logistic analysis showed that women’s age was independently associated with the aneuploidy rate (OR = 0.88; 95% CI: [0.84–0.91]; P < 0.001). The rate of chromosomal aneuploidy was significantly higher in the age > 35 years group than in the age ≤ 35 years group (61.0% vs. 39.4%, P < 0.001). Other factors, including blastocyst formation speed, were not significant predictors of aneuploidy rate. Conclusions Chromosomal abnormalities may not be a factor contributing to the high abortion rate at D6 group.