New insight of congenital uterine anomalies on pregnancy outcomes: a retrospective study based on PGT-A.

RESEARCH QUESTION: Do different subtypes of congenital uterine anomaly (CUA) differentially affect outcomes after the first single euploid frozen blastocyst transfer following preimplantation genetic testing for aneuploidy (PGT-A)? DESIGN: This retrospective cohort included 163 women with CUA, including septate uterus (n = 73), arcuate uterus [as defined by the American Society for Reproductive Medicine (ASRM)] (n = 65), unicornuate uterus (n = 21) and uterus didelphys (n = 4), undergoing their first single euploid frozen blastocyst transfer after PGT-A at Peking University Third Hospital between 2019 and 2023. They were matched 1:3 by age and body mass index (BMI) with 489 women with a normal uterus. The primary endpoint was live birth rate; secondary outcomes included clinical pregnancy rate, pregnancy loss rate, and perinatal outcomes. RESULTS: Compared with controls, women with CUA had lower clinical pregnancy [29.4% (48/163) versus 49.1% (240/489); adjusted risk ratio (aRR) = 0.599, 95% CI 0.465-0.773; P < 0.001] and live birth rates [15.3% (25/163) versus 36.2% (177/489); aRR = 0.426, 95% CI 0.292-0.622; P < 0.001], but a higher first-trimester loss rate [35.4% (17/48) versus 12.1% (29/240); aRR = 3.103, 95% CI 1.938-4.968; P < 0.001]. Subtype-specific analyses showed that septate uterus was associated with lower clinical pregnancy [21.9% (16/73) versus 47.0% (103/219); P < 0.001] and live birth rates [8.2% (6/73) versus 35.6% (78/219); P < 0.001], and a higher first-trimester loss rate [62.5% (10/16) versus 14.6% (15/103); P < 0.001]. ASRM-defined arcuate uterus was associated with a lower clinical pregnancy rate [33.8% (22/65) versus 49.7% (97/195); P = 0.037], whereas the reduction in live birth rate was non-significant [21.5% (14/65) versus 33.8% (66/195)]. CONCLUSION: Despite PGT-A control of embryo ploidy, CUA, especially arcuate and septate subtypes, remained associated with adverse outcomes, supporting an independent uterine effect and the need for standardized imaging definitions and subtype-specific management.