Analysis of prenatal diagnosis and pregnancy outcomes for rare autosomal trisomies detected by non-invasive prenatal testing in 33,079 cases.

Background: Non-invasive prenatal testing is widely used for screening common fetal aneuploidy disorders such as trisomy 21, trisomy 18, and trisomy 13. However, its ability to detect rare autosomal trisomies has introduced a new layer of complexity and clinical uncertainty.

Methods: A retrospective analysis was conducted on the prenatal diagnostic results and pregnancy outcomes of cases identified as high-risk for rare autosomal trisomies through non-invasive prenatal testing at the reproductive medicine center, Renmin hospital, Hubei university of medicine, from 2015 to 2023.

Results: 66 cases identified as high-risk for rare autosomeal trisomies, yielding a detection rate of 0.20% (66/33,079). 7 declined amniocentesis, while the others underwent the procedure. Prenatal diagnostic procedures did not confirm the presence of the corresponding rare autosomal trisomy in any of these cases. Among the 66 cases of rare autosomal trisomies (RATs), 5 cases were lost to follow-up, and 1 case underwent termination of pregnancy (TOP) for personal reasons, leaving 60 cases with valid pregnancy outcomes. Of these 60 valid outcomes, 50 (83.33%) resulted in full-term births, while 10 (16.67%) experienced adverse pregnancy outcomes.

Conclusion: Prenatal diagnosis for high-risk rare autosomal trisomies typically reveals a normal karyotype with no detectable chromosomal abnormalities, and most cases can achieve full-term pregnancy outcomes. However, adverse pregnancy outcomes such as preterm birth, fetal demise, placental abnormalities, and intrauterine growth restriction are common and should be given clinical attention and consideration.