Prenatal Findings and Perinatal Outcomes of Rare Autosomal Trisomies: A Retrospective Cohort Study

To evaluate the incidence, prenatal findings, and pregnancy outcomes of rare autosomal trisomies (RATs).

This retrospective cohort study included cases diagnosed via chorionic villus sampling, amniocentesis, or fetal cord blood sampling. Data collected included maternal demographics, gestational age, first-trimester screening results, ultrasound findings, genetic analyses, and pregnancy outcomes.

A total of 354 cases of common trisomies and 18 cases of RATs (trisomies 2, 5, 7, 8, 9, 12, 20, and 22) were identified. Common trisomies were associated with higher maternal age (p = 0.003) and advanced maternal age rates (≥35 years) (p = 0.009). Fetal (61.1% vs. 1.7%) and confined placental mosaicism (22.2% vs. 0.3%) were significantly more frequent in RATs (p < 0.001, for all). Ultrasound anomalies were observed in 11 of 18 (61.1%) RATs, with trisomy 22 frequently involving craniofacial and cardiac abnormalities.

RATs display diverse clinical outcomes. Mosaicism and ultrasound findings are critical for assessing prognosis and guiding clinical management.