Screening Positive for Rare Autosomal Aneuploidies Increases Frequency of Adverse Pregnancy Outcomes and Alters Clinical Management.

Objective: Outcomes in pregnancies with rare autosomal aneuploidies (RAAs) are poorly characterized, with most studies having small sample sizes. Here, we describe outcomes and management in a large cohort of pregnancies that screened positive for an RAA (RAA+).

Methods: Results of prenatal cell-free DNA screening were linked to de-identified insurance claims data. Diagnosis and procedure codes were used to estimate pregnancy outcomes and management. Relevant covariates in comparative analyses were adjusted using propensity-score matching. Outcomes were statistically compared using Mantel-Haenszel and McNemar's tests.

Results: Among 682 RAA+ pregnancies, the rate of live birth was significantly lower (56.7% vs. 78.7%; p < 0.001), and the rates of miscarriage and preterm birth were significantly higher (14.8% vs. 3.2%, p < 0.001; 18.5% vs. 8.9%, p < 0.001; respectively), compared to pregnancies with RAA- results. In pregnancies that screened positive for a rare autosomal trisomy (RAT+) and in which the RAT+ results were known, ultrasounds (mean: 3.7 vs. 2.5, p = 0.002), and pregnancy-specific visits (mean: 6.6 vs. 5.1; p = 0.007) were more frequent compared with pregnancies in which the RAT+ result was unknown.

Conclusion: Pregnancies with RAA+ results had higher rates of adverse outcomes compared with those with RAA- results, and awareness of RAA+ results was associated with more intensive monitoring.